# A smooth bottom is a fast bottom

You can’t be a sailor and not be a scientist. Every time you leave the dock, you become part aerodynamicist, part hydrodynamicist — even part cosmologist (when you get that urge to bang the left corner!).

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Originally Published: 07/11/2012

Article obtained at: https://www.gp14.org/a-smooth-bottom-is-a-fast-bottom/

Author: Paul Grimes. Paul was a Collegiate All-American sailor at Brown University, an engineer for Tillotson-Pearson, and is currently owner of Fusion Composites in Middletown, R.I.

From the Inernational GP14 website (www.gp14.org): The International GP14 is a sailing class. The Class Association promotes GP14 sailing and racing. There is a thriving club sailing network and training for all abilities; unrivalled championship racing, plus an active cruising and vintage fleet.

Obtained for the PMYC website: August 17, 2018. Changes were made by me to make the section headings more visible. Jerry Walker, PMYC webmaster.

_______________________________________________

## Introduction

Sometimes it’s enough just to know that something is fast, without knowing why. But with more complex questions, such as how to minimize “skin-friction drag” on underwater surfaces, you will be bombarded with different theories. Some people will tell you to wet sand, others will say to polish. Stars & Stripes had micro grooves in ’87, but maybe you need Teflon in ’96. When faced with such a variety of opinion, the only solution is to charge ahead, fearless of the complex science involved, and try to discover the truth. You’ll be surprised to find that the subject isn’t that complicated after all.

## Basic Science

The No-Slip Condition–The term “skin friction” is misleading when used to describe drag on hull surfaces. When we think of friction, we normally think of two surfaces sliding against each other. This does not happen underwater.

Fluid dynamics textbooks usually begin discussions of this topic by explaining the no-slip condition. This stipulates that the fluid molecules against a moving surface do not slide (slip) over it. Instead, they are pressed against it and adhere to it. This occurs regardless of the type of surface (gelcoat, paint, plastic), how smooth the surface is, or whether water beads up on it. In fact, if you could figure out how not to adhere water to a hull, getting it to slide by, you would have discovered a major scientific breakthrough.

Boundary Layers–To visualize what happens as a result of the no-slip condition, imagine yourself in a scary situation: an overcrowded subway station. You are part of a crowd pressed up against a train which is now full and starting to move slowly. The people who are touching the train have no choice but to move along with it, and they push those pressed up against them as well. You are 6 feet back from the train, but you, too, are bumped and pulled along, though not as fast as the train and those against it. Somewhere behind you, farther out from the train, the effect ends, and the train’s motion does not cause people to move.

What you just imagined (except for the panic) is what happens to the water molecules against the hull of a sailboat. The region of water pulled along with the hull is known as the boundary layer, and it can take one of two forms — laminar or turbulent.

When the boundary layer is “laminar,” it’s thin and presents little drag. It’s also fragile, so it quickly breaks up into a thicker “turbulent” boundary layer as it flows aft on the hull or foils. When turbulent, the boundary layer pulls more water with it, creating more drag. Therefore, the first goal of bottom preparation is to extend the laminar boundary layer as far aft as possible on your hull and appendages by creating practically perfect surfaces in the areas where it can exist.

The second goal is to minimize drag aft of the transition to turbulence, and this is a little easier to do. Most of the turbulent boundary layer consists of chaotic, swirling eddies, but there is a thin layer next to the hull known as the “laminar sub-layer.” Any surface roughness small enough to be immersed in this layer is “hydrodynamically smooth.” In other words, making it any smoother will have no benefit. This means that the hull does not have to be as smooth in the aft sections, where you know the boundary layer will be turbulent, as it does in the forward sections, where you hope to preserve laminar flow.

Let’s take a look at two examples: a boat traveling at 2 knots and one moving at 12 knots. Laboratory experiments with flat plates indicate that the transition from laminar to turbulent flow in the boundary layer should occur in the first 6 feet at 2 knots, and within the first foot at 12 knots. Boats are not flat plates, however, and they don’t sail in calm test tanks, so we need to search further for evidence of the true transition point. What the lab results do teach us is that the greatest opportunity for laminar flow is at low speeds. Note that this is also when most of the total drag of a hull is due to skin friction (as opposed to wave drag in heavy air). So the smoothness of the forward sections of your bottom and foils is most important when sailing in light air.

As for what is “hydrodynamically smooth” aft of the transition point, when sailing at 2 knots, it’s any scratch smaller than 4 mils (thousandths of an inch). At 12 knots, the “admissible roughness” reduces to under 1 mil. A human hair is approximately 2 to 3 mils in diameter, and a bottom finished with 400-grit sandpaper should have a hydrodynamically smooth finish aft of the transition point for speeds up to 7 knots. So, for most keelboats, a bottom which is finished with 400-grit sandpaper in the aft sections is adequate. For planing dinghies, which sail faster, the aft sections of the bottom need to be smoother.

## The Real World

Hulls in Waves–When sailing in real conditions, the shape of a hull or appendage works to enhance laminar flow. However, the condition of the water acts to destroy it.

Visualize water flowing past a sailboat hull. It is deflected outward by the forward part of the hull, and accelerates until it reaches the widest and deepest part of the hull. This acceleration creates a “positive pressure gradient” that stabilizes and prolongs the laminar boundary layer. The same effect exists on keels, and has led to foil sections and bulbs with their maximum thicknesses moved aft to delay the transition from laminar to turbulent.

The worthy opponent of these positive effects is the state of the water. Turbulence at the surface from waves, micro organisms, and contaminants can all be disruptive. Yacht designer David Pedrick, who has dealt with this question during several America’s Cup efforts, feels that the imperfect sea state usually wins out. “We’ve used electronic sensors and microphones to test for laminar flow,” he says. “You can get some, but not much.”

The best chance for laminar flow is on the keel and rudder, both because of their convex shape and because they are immersed below much of the disturbance. Aerodynamicist and dinghy designer Frank Bethwaite questions “whether any surface is ‘smooth enough’ for a racing dinghy,” when it comes to foils.

Smoothness vs. Fairness–So far, we have concentrated on the smoothness of surfaces, but not fairness. By fairness we mean whether the hull has highs and lows that deviate from its designed continuous curves.

On this subject, Karl Kirkman, a well-known hydrodynamicist with extensive tank-testing experience, found that hulls can be forgiving of gentle variations in shape as long as there are no sudden changes in curvature. “If there is a step or a dent in the hull,” says Kirkman, “of course that has to come out. But hulls can be forgiving of a gradual waviness unless it is in a place where it could cause flow separation.”

Pedrick agrees, but adds that, for keels and rudders, both smoothness and fairness are critical to performance.

Beading vs. Wetting–Any discussion of fast bottom surfaces eventually leads to the question of whether water should bead up on a hull or “wet” the hull so that it flows off in a sheet. “Beading has no relevance,” says Kirkman. “It’s a function of the surface tensions of the water and hull surfaces, and nobody has been able to explain to me how it has any relation to skin-friction drag underwater.”

Even so, both Pedrick and Kirkman suggest that waxes are not a good idea because they seem to attract and/or react with contaminants in the water and can be hard to get as smooth as a finely wet-sanded surface.

What About Riblets?–Riblets were used on the bottom of the 12-Meter Stars & Stripes during the 1987 America’s Cup. They are tiny v-shaped grooves that were applied to the hull on a vinyl tape (from the 3-M company). Soon after their televised debut, they were outlawed by the racing rules, which now prohibit “specially textured” surfaces that alter “the character of the flow of water inside the boundary layer.”

Fine. But what if you are painstakingly wet sanding your new bottom paint to achieve a “hydrodynamically smooth” surface. You might wonder whether you could sand carefully in a fore-and-aft direction using 220-grit paper, and then “just launch the damn thing.”

Fortunately for protest committees everywhere, this does not appear to be a smart approach. Early papers on riblets show that their effectiveness is sensitive to the geometry of the tiny grooves, and that rounded grooves are likely to increase drag.

They have also been shown to trip laminar boundary layers into turbulence sooner than smooth surfaces. As Kirkman points out, the optimum height of the riblets changes with speed, so any riblet choice is a compromise. So it seems likely that large scratches left in a surface from sanding with 220-grit sandpaper will increase drag rather than reduce it.

## Bottom Finishes

By now we should agree on a few things. The foils should be mirror smooth. For keelboats and non-planing centerboarders, if you want to go fast in light air, the hull should be highly finished at least back to the midsection. Aft of that, a 400-grit finish is adequate for keelboats. Polish a high-performance dinghy from head to toe.

But what is the best finish? Should you use paint or gelcoat? And how do you maintain that finish? Here are some things to consider.

Magic Bottom Paints–We hear about paints that repel water, paints that bond water “because water sliding over water gives less drag,” and paints with low-drag coefficients. When faced with such claims, remember that the chemistry of a paint can only reduce drag if it leads to a smoother finish — either by allowing the paint to be sprayed on more smoothly, by creating a harder surface for finer wet sanding, or by preventing growth and contaminants from adhering. Any other claim runs into the no-slip condition. It may well happen that someone will figure out how to allow water to slide over surfaces, but until then, assume the no-slip condition is alive and well, and smoothness is what really counts.

As for advertised test results showing the drag reduction of a bottom paint, common sense says to be sceptical. For instance, a 10-percent drag reduction would lead to a huge speed advantage in a one-design fleet. If that happens, you’ll know it.

Gelcoat–Sailors with production boats often worry if their gelcoat hulls are fair enough. Even if reflected light seems to “flutter” as you move your head to look at the hull, chances are that your surfaces are adequately fair. Your eye tends to be over-sensitive to this, and glossy surfaces show everything. Another boat with a duller, wet-sanded bottom may look perfectly fair; but if it were glossy, chances are that reflections would dance a bit on its surfaces, too. Unless you can actually feel roughness or unfairness, your efforts are better spent on your keel, centerboard and rudder.

Sometimes, excessive “orange peel” or “print through” is visible in the gelcoat. This means that, although the surface is often fair enough, it may not be smooth enough. If you decide to wet sand a gelcoat hull, it’s best to have a boat shop refinish the underwater surfaces with another layer of gelcoat, or an epoxy barrier coat.

Don’t sand gelcoat without good reason, however. Untouched gelcoat has a thin, resin-rich layer on the outside that helps to protect it from weathering. Removing this layer will not only cause quicker fading, it may expose porosity that is trapped in the gelcoat. This porosity is not much of a drag problem (tiny protrusions such as road dirt are much worse), but it will leave the gelcoat less effective as a water barrier to the laminate and core.

With gelcoat, the best way to maintain the finish is with soap and water. Many sailors put a layer of liquid soap on a hull before launching to keep the bottom clean while sailing out of a polluted harbor. While this is effective, the soap also adds to the pollution. As an alternative, some sailors polish the bottom. Do whatever it takes to keep the bottom free of contaminants. Remember, wax is not recommended.

If the bottom is finished in an epoxy primer, you can also wet sand it to maintain a clean, smooth finish. But a wet-sanded bottom will get dirty more quickly than a polished or shiny gelcoat surface. Here’s how they do it in the America’s Cup:

The Perfect Hull–Perhaps the best way to discover what the experts do is to check the hulls of America’s Cup contenders. These boats are drysailed, and thus do not need antifouling protection or paints that can be left immersed for long periods. However, there are still lessons to be learned.

At least among the American syndicates, there seems to be little variation from what Pedrick describes: “We start by getting the hardest surface possible. Since Courageous in 1974, we have used Awlgrip on the boats because the catalytic urethane chemistry yields an ultra-hard surface. We wet sand this to a 600-grit finish, and finish it off by sanding in the streamline directions — just to do the least amount of harm. Before launching, we put detergent on the hull to keep any oil or contaminants off.”

In the end, it’s not that complicated. Your appendages should be as smooth and fair as possible, and your hull should be just as flawless in the forward areas. Aft of where you expect transition on the hull (certainly by amidships), the surfaces need only be “hydrodynamically smooth.” Finally, when faced with the myths, remember the no-slip condition.

# \$325

This Micro Magic is available for sailing today. It has been sailed by several of our skippers and they agree that this boat can win races.

As we are always looking for ready to sail Micro Magics to make it easy for our members to get going quickly, we will leave the post here but indicated at the top of the page whether a boat is available at the moment.

# If there is not a boat available right now you can buy a Micro Magic Kit and build it yourself. There is plenty of knowledge in the Club to help you.

Perhaps you want the challenge of building a Micro Magic from a kit. Well, there are three choices. See the kits at the Graupnerusa website. The Micro Magic Race V2 kit is the lowest priced kit (\$159 – March 2018) but also requires the most work to build. It is not a kit for a novice builder. The Micro Magic V2 ARTR is also a kit but much of the work has been done for you by Graupner (\$299 – March 2018). The building remaining is documented on this website. The advantage of an already built boat as represented on this page is that you can be on the pond the day you buy it. The third kit is the Micro Magic Race Carbon V2. We rarely see this model at regattas. Perhaps it is due to its pink sale. It does have the appearance of a carbon fiber hull; though it is just a very fancy paint job.

# Micro Magic Model Yacht for Sale offered by the Pima Micro Yacht Club

## \$325

PMYC recently acquired TWO READY-TO-SAIL Micro Magic models from the Azura Model Yacht Club in Colorado. These are British-built boats and proven race winners.

International website – https://micromagic.info/?page_id=23

USA website – https://www.theamya.org/boats/micromagic/

The package is a fully rigged boat with transmitter and receiver and batteries. (See the pictures at the bottom of the post)

Breaking news: one is sold. Come sail the other one.

### THIS MODEL YACHT IS AVAILABLE TO SAIL EACH THURSDAY AT REID PARK POND AT NOON.  YOU THINK YOU MIGHT BE INTERESTED IN RACING?

Experience the fun and commoraderie of Micro Magic model yacht sailing as a member of the Pima Micro Yacht Club

“Put a little Magic in your life”

If you are interested contact Jerry at 520-461-6473 or jerryw@pimamicroyachtclub.com

If you are interested in building your own Micro Magic model yacht take a look at our instructions for building from an Almost-Ready-to-Sail kit.

## Build a Micro Magic Model Yacht (2017 ARTR version)

The Micro Magic built from the directions in this post is for sale. Purchase this completed Micro Magic or use the instructons in this post to learn how to complete the building of your own Micro Magic almost-ready-to-race (ARTR) model yacht.

# New Micro Magic For Sale by PMYC

This Micro Magic radio controlled model yacht was assembled from an ARTR kit from GraupnerUSA according to the directions contained in the kit and the contents of this Post.

Nearby is a pic of the finished Micro Magic.

The Graupner instructions are of minimal value to the assembly process. The assembly was based upon the myriad of materials on the Internet regarding this boat and my model yacht building experieince.

If you plan on racing your Micro Magic ,this post gives guidance on making the boat race-worthy.

The price of the Micro Magic ARTR kit from Graupner is \$299 (Sept. 2017).

# Introduction 1 (Will be combined with Introduction 2)

This post explains the building of a Micro Magic almost-ready-to-race model yacht.

Assembling a Graupner V2 almost-ready-to-race (ARTR) Micro Magic model yacht is a reasonably straight forward project for those who have built model yachts in the past. “Non-modelers” may be a challenged – but it is certainly doable. PMYC members have access to other members who have building experience.

The Graupner MM Manual makes the point “This item is not a toy. …. Assembly…. must be performed by experienced modelers….”  I think Graupner is overstating the matter. That said, the detail in the Manual is sparse — I think that’s an understatement.

This post has two perspectives. One is what I have named “Casual Sailing”.  The other is “Racing”. The Casual Sailing topics are, essentially, a reflection of the Graupner instructions. The goal is to get a boat in the water and sailing. The Racing topics modify the Casual Sailing procedures to reflect modifications that will make the boat easier to sail and go faster in a race. The post is not consistent throughout on this dividing because the idea evolved while assembly was underway.

My immediate focus is to complete the assembly and the Casual Sailing instructions. Upon completion of the Casual Sailing instructions I will return to the Racing info.
The Racing sections will be focused on the changes to the Casual Sailing instructions. Those changes will have to be modified by the input one receives by studying the several articles covering the building of a Micro Magic from a kit and the creation of a fast racing Micro Magic.
This post has become larger than I anticipated at the beginning. I am noticing that it is loading a bit slowly. I am going to divide it into multiple posts with an appropriate indexing at the beginning of the first piece.

The boat assembly and the Post content development are ongoing.

I am documenting the assembly of the boat as I do the assembly. So, if you are thinking about or already committed to the assembly of an MM ARTR, come back regularly. I don’t spend all of my time on this assembly or writing. So, the assembly project that I estimate will take most people 10 – 15 hours may extend over  weeks for me.

You may find this tedious reading. However, I assure you, that if you have to figure all of this out as I have done you will feel like you are building the kit from scratch — another challenging project. Be patient and work through the steps. The labor savings and resulting build quality will be worth it.

One last thing. read the “I Plan on Racing my Micro Magic

Call me (520-461-6473) if you want to discuss the topic. Or, email me.

Jerry

# Introduction 2 (will be combined with Intro 1)

Mid-June, 2017, the Pima Micro Yacht Club purchased two Graupner SA  MM ARTR (Almost-Ready-to-Race) boats. These boats are constructed by the manufacturer needing only final assembly. The idea for PMYC to buy a kit  was a hedge against a repeat shortage of MM’s experienced this year and to make it possible for persons new to the Club to easily obtain a boat that they could be sailing  relatively quickly.

The Graupner SA instructions are minimal. So, I decided to assemble the PMYC-purchased boat. And, will sell it when the boat and documentation is done. The focus of the build is  lot of research is going into this build. My sources are the multiple writings of MM gurus. The more significant of those writings are listed in the References Section below. I strongly recommending looking at all of them. My writings have drawn heavily on the content of these documents plus my experience as a model yacht builder going back to 2010.

The Manual notably lacks details and what information is there can be difficult to interpret unless you can examine a finished boat. This Post supplements the Manual, providing the desperately needed detail. It contains two perspectives on the assembly. One, to build the boat by the instruction (vague as they are). I label these sections “Casual Sailing”. This is a boat that can be assembled rather quickly and will make for a fine casual sailing experience. The second perspective is racing. I label these sections “Racing”.  This is the same boat but with multiple extra and sometimes time consuming steps, but will result in a boat that will be capable of being competitive – within the range of your boat handling skills and racing expertise. If you only interest is the casual sailing then use the label info. only.

As I said above, the focus of this post is primarily to help non-modelers. I have tried to give the guidance in a way that requires the least amount of purchases of tools and materials. If you are a modeler and/or have many, many tools, use the guidance to help yourself pick out the right tool or a better material based upon your experience.

Beyond the contents of this Post you can ask PMYC members for advice. And, be sure to look carefully at other boats for fitting-out ideas. A particularly good source is Jerry Robertson, Bill Brown and myself.

The emails for these PMYC members are:

A link to this Post is on the menu at the top of each page on the website (Assemble a MM V2 ARTR) so you can easily find it. It will be updated as I go along with pictures and narrative. As I am writing and assembling, I am thinking about assembling a package of “stuff” (I don’t really know what that might fully mean at the moment) that could be purchased along with the boat to make the assembly easier — removing most of the need to make yet another run to the hardware store.

# References

If you are new to sail boats check out these documents that are available from the American Model Yachting Association (AMYA).

## Boats and Sailing – from the AMYA website

New to sailing? Take a look at these documents.

## Articles

• Remember to read the Summer 2017, #188, issue of Model Yachting magazine — available from the AMYA website. Several articles appear there that are of particular help in the assembly project. This issue of Model Yachting is a must have if you are to be a Micro Magic racer.

In this post (the one you are reading), references to Mike Eades or Greg Norris are references to the above two documents.

## Model Yachting

• If you do not receive Model Yachting magazine, please support model yachting in America by joining the American Model Yachting Association. It costs \$35 annually (\$5 fee for the first year). The magazine alone is worth the price if you getting into model yachting.

## Want to race?

Take a look at this Facebook tuning video. As usual with Facebook, at the end of one video there are always additional related videos. Check them out.

Take a look at this tuning guide.

Also, if you want to race be sure to look at hte

# Materials Needed In Addition to the Box Contents

The following is a list of items, in addition to those in the box, that you will need to do the assembly — prices are approximate where given. For my own convenience, I looked up item prices on the Internet. So, the numbers I give may be a bit low compared to local stores. For what I want to accomplish here they are good enough.

## Stand Assembly

• two wood blocks (2″ x 6″) to stabilize the stand-ends during assembly – get them at your local hardware or lumber store for free from their castoffs. – \$0
• Wood screws size: xx phillips head (for securing the stand ends to the wood blocks during assembly)
• Varnish or paint to protect wood – optional (krylon Clear Interior/Exterior spray – \$5.)
• A simpe carpenters framing square 8″ x 12″ (See pic on right) – \$5 – borrow it if you don’t have one
• Drill to drill holes in the ends so that they can be stabilized during assembly.
• Phillips screwdriver – borrow it if you don’t have one

## Thick CA (30 sec. set) – \$5.

Note: when using thick CA, you can instantly make it set by sprinkling Baking Soda on it. It makes the surface rough but does the job.

## Nail Polish – \$.99

You will only need a small bottle of wet-n-wild Clear Protector. Used for cementing knots. Slower drying than thin CA for setting knots, but easier to control.

## Hull

• Sheets – Tufline XP 15# – replaces the lines that come with the kit.
• A small amount of 1 mm plastic sheeting to build a mounting platform for the screw eye for the jib sheet. See the xxx figure.

## Rudder

• Allen keys (hex wrenches) – 1.5mm and 2.5mm. If you do not have a set of these keys, you can buy them at Ace for about \$1.00 each.

## Sails

• Sail Tape or Sail Patch Tape – approx. \$23 for 3″ x 15′, enough to strengthen the luff of the MM sails for 60 boats (3″ x 3″ piece). This could be part of a “PMYC MM Building Package” NOTE: I have enough to support the build of a dozen boats.
• Sail Numbering Tools. I have access to my wife’s quilters cutting mat, transparent grid tool and rotary cutter. It made the number application process easier. If someone in your household does quilting your have an immediate leg up on the sail application process.  Check around your neighborhood for a quilter. For reference the two products shown are made by Creative Grid and Crafty World (look them up on the Internet). The grid is 6″ x 12″ and the mat is 24″ x 18″. The mat is a bit pricey for this one project. So, the same carpenters square identified above would work as well. Use the grid that is in the sail material to help align the numbers.

# My First Impressions

My first impression upon opening the box is that Graupner does an outstanding job of providing a ready-to-sail product. Everything in the box was secured and neatly arranged. There were multiple packets of parts. The most impressive part of the package was the hull. It has a gleaming white painted finish that was obviously done by someone with a paint gun and skilled; not a spray can. The finish is smooth and dust-free. It was not until a few days after I opened the box that I removed the canopy. I was surprised at the neatness of the interior installation which included the servos and the power switch. If one does not particularly care to build a boat this is a great solution.

If you want to see the boat I have let me know. Unless you are strongly motivated to build, this is an excellent way to get into MM sailing.

Jerry Robertson and I agree that this boat is more fun to sail than the Victoria. The MM is very suited to the Tucson wind conditions. In Europe, it appears from the video available on the Internet that high winds are common. In contrast, here in Tucson, we will experience “too much wind” at most twice during the year. The rest of the time, we will usually be sailing in 0 – 10mph  conditions. We know from our experiences, that sailing in strong winds with our little boats is very challenging and, sometimes, not so much fun. Our light air is perfect for the MM.

# MM Class Measurements

The items in the list reference the Micro Magic Class rules paragraph number. See the MM Class Rules.

Class Rules referenceRule ValueThis Boat Value
2.1 – Weight of ready-to-sail boat (not including wind vane/tell-tale)860 gm (min)963 gm (Note 1)
3.2 – Axis of rudder from inner back-side of keelbox=210 mm205
3.4 – Bottom of lead ballast to the hull=135 mm137+ mm
3.9 – Leading edge of keel to front tip of bulb=> 25 mm 38 mm
3.10 – Weight of the keel assembly including spacers380-420 gm 415 gm
4.10 – distance from the deck to top of mast<=780 mm
4.12 – Middle of mast-positioning slot to the jib boom deck connection =176 mm 176 mm
Mast diameter> 5-7 mm 5/6 mm (Note 2)
Boom diameter>=4 mm 4 mm
 Note 1 – Weight is with the plastic AA battery pak that came with the kit and Duracel batteries. Changing the battery to a 4-cell AAA shrink wrapped pak would reduce the weight by about 65 gm. leaving the total weight at about 900 gm, or less than 2 oz. “over weight”. Replacing the clunky receiver that is in the boat at the moment with a lighter receiver would yield more weight reduction. Note that his “over weight” condition is only of interest to hard core racers. Good boat handling skills and solid racing knowledge easily overcomes the excessive weight in all but the most competitive situations. Note 2 – Top and bottom of mast are 5 mm, center is 6 mm.

The MM V2 ARTR boat may not adhere exactly to the Class Rules.  See Blue items in table above. The following paragraph is from the Micro Magic Class Rules – 2017.

IMPORTANT!
Recommendation concerning the Ready To Race (RTR) boats.
These boats, entirely built by Graupner, like the Graupner 2014 HOTT or RFH (Ready For Hott Version), may not be 100% class-conforming. Their keel may be a little too long and slightly overweight. Also the position of the jib and rudder may be different a little bit.
Nevertheless the organizers of a Micro Magic Regatta are advised to accept these boats to participate for the time being. This is very important for the growth of the class. Exclusion of these boats could mean that new MM-sailors with such a boat are not allowed to race, and this is undesirable.
July 2017 – Since this addition to the rules was made the manufacturing has been moved to China. The Chinese boats will be available in the USA in mid-August.

Editor: The new boats are expected to be available before the end of August, 2017.

# What's in the Box?

## Deck from the front of the cockpit to approximately half way to the bow.

Mast positioner (black piece) and jib sheet exit (round button) from deck. The white line entering the deck at the jib sheet exit is the jib sheet. At the top of the image, you see the cabin top in place. Near the bottom, is one of the components associated with the jib boom attachment.

## Rudder post, rudder push rod, the mail sail sheet entry hole and the main sail adjustment are assembled and installed.

At the top of the image is the cabin top with two of its retainers.

###### Sail sheets are installed - cabin top removable for radio and servo access

Note that one sheet, the main comes out onto the rear deck; making for easy and quick sheet length change. The jib sheet adjustment is below deck

## Micro Magic decals.

The two black pieces in the lower left corner are the side "windows" for the cabin top. (See the Cabin top image above) The rectangular piece to the right are the "front' window and the piece with the white lines is the "cabin top" hatch. Place the square edge of the cabin top decal at the rear edge of the cabin top. The blue and black pieces are attached to the hull just below the deck edge. Do what you want with the other pieces. The estimated weight of the decals is 2 gm.

# The More Detailed Parts of the Kit  are Already Assembled

The hull, mast and keel are completely assembled.  This is a step that allows you to skip about 10 hours of build time compared to building the kit. The completed items include:

• The sail and rudder servo platforms are in place and the sail and rudder servos are installed and the arm connecting the rudder servo to the rudder in the cock pit is installed.
• Keel box is in place
• All deck fittings are installed
• Deck is glued to hull
• Rudder tube extending from the bottom of the hull to the top of the deck are installed
• The keel is assembled
• The sail sheets are installed. Note: the sheets are replaced for racing — and that I did change them in accordance with the Racing section below.
• The mast and boom are assembled, including stays and jib topping lift
• The sail and rudder servo arms are installed
• the boot for the rudder push rod is in place
• The rudder servo to rudder push rod is installed
• Hull and deck are painted – and the job was well done
• The sheets are in place. The jib sheet routing in the boat was changed. See Jib Sheets section below.

Note: you must provide the receiver and battery. This will be covered further along in this post.

# How Long Does it Take to Complete the Job?

It depends. Some of the variables are:

• Your prospects of racing it.

My estimate of my build time, with a lot of writing time interspersed is about 10 hours. This will vary significantly depending upon your comfort level with this kind of project. However, it is not a difficult project. It does, however, require patience.

# Important stuff before we start the assembly

## Sail Terminology that is used in this rigging section.

If you are not familiar with sailboat terminology, it will be helpful to carefully study the diagram. I did the details in the diagram to match the Micro Magic as close as I could.

The diagram will be most easily viewed on a computer screen.

## Square Knot or Reef Knot: the knot of choice for tieing string on a model yacht.

The Reef Knot or Square Knot is quick and easy to tie (Section 9). This knot was used for centuries by sailors for reefing sails, hence the name Reef Knot, and tying things aboard ship. This is the knot you will use for the knots needed to build your rigging. As soon as you tie a know on your boat put the dab of thin CA or nail polish on it. If you use thin CA, it will set in a few seconds, nail polish takes a little longer.

## Use thin CA or a clear nail polish to secure knots.

If you opt for the thin CA, be careful with it. It's very thin and runs along cracks in materials and along thin string, frequently ending up on your fingers - and, all too often, sticking them together. The bottle label indicates a set time of 1 - 3 seconds. That's instantaneous. A very small amount is all that is needed to secure your knots. A wooden toothpick works well. When you are applying the CA keep a folded half paper towel under the knot, in case the CA drips. When you are working with CA on your work surface, keep a piece of waxed paper under the work. CA does not stick to it. With CA you can put tension on the knot almost immediately. The nail polish won't run and won't stick you fingers together before you can clean them. That's all good. However, it takes some time to set. Do not tension the know for a minutes. Not a big deal, but it must be remembered. To avoid the Dyneema cord fraying when cut, put a few drops of thin CA glue into the cord at the position of the cut then cut through the glued cord at an angle. You will then have a hard, sharp point to the cut end that will be easy to thread through the Bowsies.

The thin CA sets in a couple of seconds - great when you are "sealing" a knot. When you are using the Thick CA, the set time is more like 30 seconds, but is a great gap filler and a good selection when you want the joint stronger. However, the longer set time is not always desired. When you want the CA to set "immediately", sprinkle a litter baking soda on it. Depending upon the situation, you may want to sand the joint a bit as it will be rough.

## Glues

This item was obtained from the article written by Greg Norris that appeared in the Summer 2017 issue of “Model Yachting” magazine. This article was developed in te context of building a Micro Magic from the kit. In the ARTR build virtually all of the gluing steps have been completed. I include it here because it is information all model yacht bulders should know.

“And it’s a great time to talk about glues:  ABS to ABS you should use an acetone based glue.  I screwed up and missed an early tip from Ralf to use Uhu Plast Special (hereafter “Plast”).  Instead, I used Testor’s model cement and it was very much less “hot” than the European stuff that I’d used previously. For wood or brass to ABS, as well as for ABS to ABS when I couldn’t clamp well, I used a German epoxy not available for purchase in the US – Pattex Stabilit or Uhu Acrylit (hereafter “Stabilit”). It’s clamp time is about 10 minutes, which means that you can hold pieces in place while they are drying when clamping is hard.  And the bonding of whatever to ABS is fabulous.  Highly recommended.  Just a reminder:  be sure to rough up any surfaces being glued with 100 grit sandpaper, then clean them with naphtha (lighter fluid) prior to gluing.”

## Using a bowsie

The above image is of a bowsie demonstration board I assembled a few years ago to help Club members understand the difference between how the two ways to string a bowsie work. Note, that the rubber bands represent the boat part that you are adjusting (or you can think of it as the load). That could be a sail adjustment, the length of a sail sheet, or a sail halyard. So, the right end of the rubber band as the item being adjusted. The top example indicates it is 1 X 1 meaning that for each 1" movement of the item/load the bowsie must move 2". The meaning to you is that the 2 X 1 method allows for finer and easier adjustments. I use the 2 X 1 method for my sail sheet and halyard and forestay adjustments. When the space available for the bowsie to move is restricted I use the 1 X 1 method.

## All of the rigging is done with fishing line

I suppose that the string that comes with the boat is fine. My persoanl preference for model yacht racing has been to rig with a fishing line. My own Micro uses the TuffLine 30# line for the fore and back stay. I use 15# TuffLine (Walmarts; \$20/150 yds) for the sail sheets. Also a good choices are the PowerPro products (Walmarts; approx. \$15 for 150 yd.). The PowerPro and Tuffline products are easier to work with than the string that comes with the kit. And, I do not know anything about the strength or durability of the string that comes with the boat.

## Working with Carbon Fiber materials

The mast and booms are made of carbon fibre. Carbon fibre dust and fly is considered hazardous to our health. Excercise caution by wearing a dust make when you are cutting or drilling this stuff. For reference, I use the 3M 8577CA1-C-PS Chemical Odor Valved Respirator, 2-Pack. You can buy them locally or for \$11 on Amazon.

# Micro Magic Assembly

## Step 1 - Register Your Boat with the AMYA and the Micro Magic Class

### American Model Yachting Association

Join the American Model Yacht Club (AMYA) by joining. The annual cost is \$7 with a first time extra cost of \$1. Your dues help the AMYA continue its activites on behalf of model yacht owners all over the country.

### Register your Micro Magic with the Class Secretary

Also, please register MM with the Class Secretary. What you get for registering your MM with the MM Class Secretary. File the red card. Place one of the white stickers on the inside hull of your boat about an inch below the deck. It would be good if you could also place a piece of transparent packing tape over the sticker so that it can't get wet. Upon registering your MM you will receive, from the MM Class Secretary, a registration card, two stickers identifying your sail number and two decals of the MM Class. This process will take about a week. See Fig xx). Contact the Micro Magic Class Secretary to register your boat.

## Step 2 - Assemble the Stand (MM 7)

### Assemble the wood pieces

Assembling the stand was one of the more frustrating tasks I have undertaken in a long time. The long front and rear cross pieces are slightly warped making a straight forward assemnbly impossible. There may be an easy solution but I don't know what it is. Maybe Jim Haines will improve this section when he builds his boat.

So, the challenge is to either find a way to strap it all together before you glue, fight the twisting or make new pieces. I chose to fight -- not especially bright, but...

I used small wood screws to attach the stand-ends to wood blocks to temporarily stabilize them while I worked. (You can see the blocks under the stand in the image above.) Then one at a time I added the cross pieces fastening them with Thin CA. After I completed the assembly I removed the screws then went back to the joints with the Thick CA. With four slightly twisted cross pieces, the resulting assembly was inevitably also twisted. The good news is that the boat on the stand puts all four corners down on the table. so, in the end, it's not a big deal. Even better news is that the stand straightened out after the boat had set on it for a week.

Finally I put a coat of clear finish on the stand to protect it from moisture. That process caused the wood grain to rise. But, a light sanding with fine sandpaper made the surfaces smooth .

### Add the hull cushioning pieces

After assembly, put the black thin strips with the sticky back on the tops of the end pieces to serve as a smooth surface for the hull to rest on. I found that one piece served both ends. So, I have an extra piece. The challenge will be keeping track of it over time.

Here is a Comment submitted to this Post about the stand on July 1.

The wood stand issue that Jerry Walker points out here may be common to many MM boats either in either kit or ARTR form. I opened my own ARTR package only to find that two of the horizontal plywood braces for the stand were in bad shape. The braces are made of a thin (0.5mm) solid wood core with a single layer of nearly paper thin wood laminate on each side. The laminate on one side of each brace was delaminated nearly completely from the core. I attempted to re-glue the laminate to the core but it ended up a floppy, twisted mess. I would suggest buying a sheet of plywood at the hobby shop and making your own sturdy braces to replace the faulty Graupner parts. Don’t waste your time on re-gluing.
Jim H.
PMYC member and MM builder

## Step 3 - Hull and deck

This step does not have an equivalent in the Manual.

### Check the hull for leaks

There are three potential places where water can enter the hull. The two small ones are the holes on the deck where the sail sheets pass through the deck. There is nothing we can do about these holes. Water will only enter the boat through these holes on windy days and then usually only in small amounts. On windy days i put a 1″ square piece of sponge. After each race I squeeze the sponge removing all of the water. Micro Magic owners also tend to put a hole in the deck near the transom and insert a plug in it.

Remember that the MM ARTR has been partially assembled. The rudder tube and keel box have been installed and the deck attached. You need to  make sure that water cannot get into the hull around the keel box and the rudder tube and any where along the deck/hull joint. Put the boat in the bath tub or pool and push it down until the water line is near the deck. Look for leakage inside the boat.  Also, put the boat on its side in the water submerging it along the deck/hull joint, again looking for leaks. Fix any leaking with some silicon seal. If there is any leakage along the deck/hull joint I recommend sealing the joint all the way around the boat.

### PAINTING THE HULL/DECK

Note that the hull and deck have been painted. And, a very good job was done. That said, you can add color to the deck and/or hull as you desire. Be sure to sand lightly with 400 Wet or Dry, wet before painting. Use any good quality spray can paint. You can finish off the look by painting a thin colored line along the water line. Put the boat in your bath tub or pool.Put pieces of  paper tape along the water line. Mark the hull with a pencil and then apply masking tape on the hull. Then apply another line of tape 2 mm away. There is masking tape available at hobby stores that makes a very fine line for your painting. When the tape is removed after painting the line is clean. Carefully complete the masking and paint. I’m sure that there are other means, probably easier, to get this water line on the boat. The alternative to painting is the colored vinyl pinstriping. Again, a hobby store is a good source.

### APPLYING DECALS

Apply the decals.

### BATTERY STRIP

The battery strip is for mounting the battery in the boat in a manner that the battery can be moved aft on a windy day. The original placement of the velcro on the plastic strip is not conducive to effective use. There are  three pieces of velcroon each side of the plastic strip and three on the bottom of the boat as well. Our goal is to make the insertion and removal of the plastic strip easy and quick.

Remove the two squares of velcro on the bottom of the hull under the rear deck — keeping only the square immediately behind the servo platform. And, remove two of the three squares on one side of the strip and make a round indent in one end as shown on the Figure.

### Jib Sheet Routing - General

Routing of jib sheet from bowsie adjustment in cockpit to the jib. See the nearby figure for detail about the screw eye turning point on the keel box.

### Jib Sheet Routing - the turning point at the front of the cockpit

Note the orange rectangle in the center of the figure. The color is to draw attention to the area. A 1/8" screw eye was embedded in a piece of plastic cut out of the unused keel spacers. I made a groove on one side of the piece, put the screw eye threads into it and cemented it to hte vertical piece shown in the figure. This screw eye serves as a turning point for the sheet coming off of the servo arm and makes its way to the cockpit and a bowsie adjustment. The line running from the screw eye through the photo date in the lower right corner is the sheet going to the cockpit.

### Painting the hull and deck

Here is an example of the hull and deck finishing done by or most creative member, Bill Brown.

A big challenge to becoming an above average model yacht racer is developing your boat handling and racing skills. As your boat handling skills and racing skills improve you will be looking for other ways to go faster. One of the long term goals you will have is to keep the boat as light as possible, ie. no more than 860 gm. Paint adds weight. You will see many videos of Micro Magics on the Internet with very nice paint jobs. And, surely a good number of them do well at regattas. Enough said. However, DECALS Apply the paint words to decals.

## Step 4 – Install the Rudder (MM 8) (Micro Magic instructions, pg. 8)

### Casual Sailing

#### GENERAL

The instructions, Page 8 are a little hard to follow. But, it is just three parts; the rudder, a spring and the arm. The push rod post has already been added to the rudder arm — see the right side of the page near the Allen key for this assembly. You will need a 1.5 mm and a 2.5 mm keys in the future to make adjustments to the boat. If you do not have the two Allen key sizes: 1.5 mm and 2.5 mm, you can get a set of metric keys at Ace, making sure that the two sizes ares included. You will need these two keys in the future to make adjustments to the boat. The 1.5 mm key also fits the post on the rudder servo arm in the boat.

The rudder shaft is steel and will rust. Simply use petroleum jelly to grease it. And, periodically, remove the rudder, clean the shaft with steel wool or kitchen cleanser and replace it, renewing the grease. I am not going to lube the shaft until the end, in case I have to remove the rudder during the rest of the boat assembly.

#### CONNECTING THE SERVO AND RUDDER ARM

The positioning of the rudder push rod oat the two ends needs a bit of explaining. (See Rudder/servo connection image . Notice that the connector on the servo end of the rod is in the last hole. The connection is on the inner hold on the rudder end.

If you do not use these two hole positions you will find that the rudder arc is narrow and that the boat does not turn easily. If you have a transmitter with a Travel Adjust setting, then also adjust the travel so that you get about a 45 degree travel on each side of neutral. If you do not know how to make setup changes on your radio contact a local hobby shop (In Tucson contact Hobby Town on E. Speedway.). As a last resort, read the transmitter manual.

See the next section for dealing with the hole in the rudder-end control arm.

#### RUDDER ARM POST NOT SECURE ON MY BOAT

In the process of moving the connector post to the inner hole in the rudder control arm, I noted that the threaded lock nut fitting on the underside of the connector on the rudder arm was not tight – and could not be tightened without binding. Worse, the nut could not be threaded on far enough to engage the locking portion of nut. My solution was to drill out a small indent in the bottom of the arm – enough to allow the lock nut to engage the threaded post. Be very careful with the drilling. The bit tends to bind in the soft material of the arm and could go all the way thru – then time for a new arm.

### Racing

#### A. RUDDER TUBE PROTRUDING FROM BOTTOM OF HULL

I ground down the metal rudder tube protruding below the hull so that the rudder fit closer to the hull. You may have to shave the top edge of the rudder slightly to make it fit the hull shape.

## Step 5 – Install the Keel (MM 9)

The MM instructions, Page 9, do not identify the spacers needed for keel installation.  You will use the narrow spacers. Discard the wide ones.

The keel fits very tightly inside the keel trunk. The first step is to sand the keel box a bit with particular emphasis on the immediate opening at the hull. It appears that paint has gotten inside. Also sand the keel insert until the fit is snug but not tight. Never force it in, as this could blow the keel box apart, and that is a very difficult repair.

Use a 1/8″ drill bit to open the deck hole a little to allow passage of the screw. There was paint in it making it a bit too small for the screw on the top of the keel.

The keel will be centered in the slot. This means that only the narrower of the spacers will be used, one each on the forward and aft side of the top of the keel.

Insert the keel into the trunk until it won’t go further. Move it back and forth until the screw comes out of the hole. The screw will be sticking out of the deck by about a 1/4″.  Put the washer and nut on the screw sticking out of the deck and finger tighten it.

Notice that the forward edge of the keel is recessed in the hull by about 2 mm. That is expected with the MM.

The keel is installed. The topic of the angle of the keel bulb to the water line will be revisited at the end of this post. Meanwhile its time to move on.

## Step 6 – Check the Alignment of the Keel and Rudder

### Casual Sailing

Any misalignment of the rudder and keel is of no consequence.

### Racing

At this point in our assembly, you can check the alignment by putting the boat on the stand and then sighting between the keel and the rudder. This boat’s keel and rudder are slightly out of alignment. Note: my own MM, #180 has the same condition — built from a kit. The is an item that needs to be investigated with the MM gurus. I put it on the Finalizing Items list at the end of the post.

## Step 7 - Obtain an RC Transmitter/Receiver

The topic of transmitters tends to be very personal. All of the better known transmitter brands are of good quality. You may find that everyone you talk to has their own preference for a radio and thinks all of the others are inferior. If you need a radio, talk to the guys at the pond. Find out there reasoning for purchasing their radio.

If you plan is to sail for the enjoyment of it, you do not need to spend very much money on a transmitter. For, instance the Hobby King 2.4Ghz 4Ch Tx & Rx V2 (Mode 2), including a receiver at \$24 will be sufficient.

You can view this radio at the Hobby King website by clicking on the image.

If you plan on racing see the "Upgrading the Transmitter" section for a suggestion on a transmitter and receiver.

Heads up when dealing with Hobby King.

1. HK has a USA warehouse (in Oregon) and, what they call "Global" warehouses. The only Global warehouse that I know of is in Hong Kong. Shipping charges are incurred from each warehouse and an order including items from USA and Global are shipped separately. I recomend placing two orders, one from each warehouse.

2. when one is in the check out process means of shipping choices are offered. The first choice is free and is pickup at the warehouse. Go slowly here as free is not "FREE" unless you are in Portland. Unfortunately, an order placed from outside of Portland is not prevented from choosing the free shipping option.

3. As you decide to include an item in your shopping cart make note of the warehouse designation. Some items are USA only, some Global only, some both. Be sure to select USA if given the choice. In my experience, items from Hong Kong have rather high shipping charges. That said, shipments from Hong Kong only take a few days.

## Step 8 - Get power in the boat

### Battery Option 1 - battery holder for AA/AAA batteries

The simplest battery solution is to use the AA battery pak that comes in the MM box. You can use Duracell Alkaline AA batteries that can be found everywhere. Note, Costco has the best battery prices. Simple (non-rechargeable) batteries will power the boat for at least a half-dozen outings of 2 or 3 hours each. The Duracell AA battery at Costco has the part number MN1500. I suspect that this is a 1500 mah battery; plenty for the MM.

### Battery Option 2 - 800 mah AAA 5-Pak

You can also use rechargeable NiMH AA batteries with the battery pak. The 5-pak pictured can power the boat for at least several 3-hour outings. It weighs 64 gm. If a four-cell pak is used the weight drops to 52 gm.

A 5-pak of cells can be obtained on the Internet. The one shown above was built by Batteries Plus while I waited. I had to provide the pigtail.

See the charger discussion below about chargers.

### Battery Option 3 - LiFe/LiPo

LiPo or LiFe batteries are 6.6 V. An 1100ma battery costs approximately \$35. A compatible charger is going to cost about \$50. My research suggests that a five-cell AAA pak will weigh about 10 gm less than the LiFe equivilent. At \$85 for a battery adn charger is appears that the NiMh is the better choice.

### Battery Charger - Tenergy TB6-B Balance Charger for NiMH/NiCD/Li-PO/Li-Fe Battery Packs + Power Supply

If you are needing a battery charger I recommend one that can charge our common AA and AAA batteries as well as the LIPO's. I say this because I suspect there is Li technology in all of futures. Here is one that is able to do it all. I do not have experience with it but the Internet write-up was impressive. \$60 on Amazon.

Alternatively, you can purchase a Prophet Sport Ni-MH, a charger only for NiMH and iCD's for \$30, plus a few more dollars for a cable adapter.

## Step 10 - Prepare the sails for install

### Put the sail numbers on the sails

Add the sail numbers and your country code, if desired. Having numbers on your sails is mandatory for participation in Micro Magic Class sanctioned racing. PMYC requires a sail number though MM Class registration is not required. Any number unique among those in the local fleet is acceptable. That said, I strongly recommend registering your boat with the Micro Magic Class. By doing so you are supporting the work of the Class.

Putting your numbers on the sail before it is on the mast is much easier than after it is on the boat. Get your sail number by contacting the Micro Magic Class Secretary. Send your sail number request to mm@theamya.org.  The sail numbers are three digits. You can request a specific number though there is no guarantee of its availability. Ask for several numbers. Or, in my case, I asked for a number with sevens and ones. I got #717. This is a number that is easy to put on the sail. You can pay by check or PayPal (perhaps some credit cards).

Putting the numbers on the sail is tedious but not difficult. The greatest challenge is to end up with the numbers evenly spaced and more or less parallel to the water. See the Figure of my sails. I will give the dimensions I used for your convenience.

Number and country approximate positioning on the sails Jib with numbers near foot of sail Main Sail with numbers near middle of sail. USA letters not on yet.

Example - Sail and numbers template taped to cutting board. Use Sharpie to draw the numbers on the sails Now for the number positioning on the sails. The size of the numbers and letters on the sails are specified in the "Locating The Numbers on the Sail" in the Reference Section near the top of this Post. The document referenced provides an exact size template for the required lettering, the MM logo and the numbers 0 - 9. The MM Class rules do not address the detailed placement of the sail numbers on the sail.

The MM Class Rules state: The mainsail must display a class provided sail number and country designation.... Letters and numbers should be of a good contrasting color and completely filled in.

It is conventional to place the numbers on the starboard side of the sail above those on the port side.  The placement of hte numbers is identified in the "Locating The Numbers on the Sail" link in the Reference Section near the top of this Post.

Noting the comments in Greg's article, I measured the above-deck part of the mast. It is about 28 5/8 ". With the boom and mast installed on the boat the distance between the top of the boom and the bottom of the mast head crane is 5/8".

### Put the metal rings on the mainsail luff

The main sail has holes along the luff for the metal rings. Install the rings - with the temporary exception of the top one (the top ring is above the jib mount fitting on the mast). For consistency place all of the rings in the same direction.

With the rings installed insert the mast , foot first through the rings. Add the top ring.

Attach the string at the top of the sail to the mast crane, using the hole next to the mast. Position the sail abut1/4" down from the crane.

### All of the strings for doing the rigging are already connected

The strings for the rigging are already connected to the masts and booms -- in addition to the sail sheets installed in the hull to the boat.

.

##### Jib and forestay preparation

There are three strings attached to the mast near the top. The short one connect to the top of the jib. the other two ware intended to be side stays (connect the mast to the eyes on the edge of the deck at the mast line) We are not going to use the side stays as the carbon fiber mast does not need side-to-side support.

One of the long strings will be the forestay, the other will be the topping lift (attaches to the aft end of the jib boom.

The mast is fully assembled. The string connected to the end of the mast crane (the thingy attached to the top of the mast) is the back stay. The long strings attached to the jib attachment point (the strings extending to the left of the mast) are the topping lift (string connects to the aft end of the jib boom) and the jib fore stay (string connects to the deck at the bow). The short string attached to the jib attachment point is the jib halyard -- attaches to the top (head) of the jib sail.

## Step 11 – Mast & Main Sail

Remove the two pieces of tape from the mast. We’ll sort out the use of the strings later.

The total mast length is 31 7/8″.

## Step 12 - Mast & Boom Installation Preparation

### Prevent the gooseneck from rising on the mast

The first time you put the mast and boom on the boat (just to see what it looks like) notice that the mast goes down to the bottom of the hull and that the gooseneck (the part at the bottom of the mast that contains the boom mount) fits into a matching slot in the deck. Also note, that the gooseneck is not restricted from moving up the mast -- disengaging from the deck and rotating. Not good. Wrap a couple of turns of line around the mast just above the gooseneck and set it with a drop of thin CA. Do not glue the gooseneck to the mast.

### Side stays are not used; topping lift is added (MM 13)

With the use of a carbon fiber mast the side stays are not needed on your Micro Magic. We will not be using them. Note the three lines connected to the mast about 3" down from the top. Remove one of them -- cut it off being careful not to cut the second line. We will use the second line as a topping lift for the jib. A topping lift connects to the aft end of the jib boom and provides a means to bend the boom, changing the shape of the jib and facilitating air flow over the jib and main sail. When you have the jib boom on the boat and connected you will notice that tightening the topping lift bends the jib boom putting more tension on the forestay and allowing the jib to bow out from the boat when under sail. Don't put more than a very little tension of the topping lift until the boat is ready to go in the water. Then talk to someone at the pond about what various tensions do to the boat's sailing.

Needs text.

### Main Sail Downhaul (also referred to as a cunningham) (MM 13)

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# I plan on racing my Micro Magic

## Introduction

Everything that has preceded this section has been focused on getting your ARTR boat in the water. The details of making the boat as fast as possible are not addressed. This section addresses some of those topics that can improve your boat’s performance. If you are serious about the racing, you might want to build your boat from a kit. Most importantly, in order to do your best racing it is recommended that you read every thing you can find about Micro Magics, starting with all of the links in this post.

## Note to Magic Micro racers about rigging materials

If you are going to race your new model ist is suggested that you replace the fore and aft stay, topping lift and sail attachement lines with the fishing line. See the section “Replace the rigging string that came with the model”.

## Keel length

As you have already read in the Class Measurements section, the MM ARTR is not totally compliant with the class rules. Compliance with Rule 3.4 is straight forward. Shave the top of the keel insert to get the measurement in compliance. Establishing compliance with Rule 3.3 i. will require removal of the rudder tube and resetting it. That is not difficult but will require some redo on the construction and will be a bit tedious.

## Wet sand the hull for speed

Wet sand the hull using 400 and 600 grit wet or dry paper. A shiny surface is not conducive to speed.

## Keel angle

There is another matter that is important to MM performance. That is the angle of the keel to the surface of the water. When this keel was installed after the spacers had been inserted, the bulb was pointed downward by a couple of degrees. Greg Norris' "Building a Micro Magic" article appearing in the Summer 2017 issue (#188) of Model Yachting and on this website (http://pimamicroyachtclub.com/2017/04/27/building-micro-magic-gregg-norris-may-2017-model-yachting/)  addresses the topic of the preferred angle of the keel bulb relative to horizontal in the section titled "On to the keel fin and bulb and rudders". In that section, it is desirable to have the front of the bulb angled upward between 0 and 3 degrees. Given that the keel on this current boat is already built we cannot exactly follow Greg's instructions. My approach to assessing (and fixing) the bulb tilt are presented in the "Bulb Tilt" section at the end of this post.

### Taper the aft edges of the keel and rudder

Taper the aft edges of the keel and rudder until they are quite sharp.

## Reduce the weight

The minimum allowable weight for a racing MM is 860 gm. Do your build carefully as it is difficult to achieve the 860 gm. goal. Don’t put stuff on your boat that is not needed for its durability or speed. Read the MM articles. It will help you keep a “light as possible” mind set during the build. Reduce the total weight by what ever means you can identify. Start with a lighter battery pak if possible.

I thought I did a good job of paying attention to the weight. How did that pan out? Almost 100 gm overweight. That just under four ounces. My 5-cell AAA battery pak is light – 64 gm. And, there is no lighter alternative.

### Move the holes in the main sail closer to the luff.

Make new holes along the main sail luff offset from the existing holes by 1/4″ (this is keeping the original and new holes separated). We are doing this to allow us to control how far the main sail luff edge is separated from the mast.

If you choose to use the metal rings this will move the sail off of the mast a bit more than with the original holes.

While you aer doing this step, consider also, replacing the metal rings with fishing line.

### Replace the rigging string that came with the model with 30# fishing line

Describe the use of the fishing line for stays and topping lift.

## Change the main and jib sheets

Mike Eades recommends changing the main and jib sheet materials. Mike recommends a 50# test line. I recommend the 15# TufLine XP line. A spool contains 300 yards, enough to do more than a few boats. I have used this product on two Victoria models for three years without visible wear or breakage. A big benefit of this product is its high flexibility. The sail positioning will never be influenced by a stiffness in the sheets. It is easier to make this change now as it will be tedious once the mast is on. Make the new sheets the same length as the original and reuse the bowsies. (Jim Haines is experimenting with a smaller bowsie. This post will be updated to reflect his experience.) For this project I changed the sheets.

## Make a wind vane

This 3 gm. wind vane uses an .8 mm OD while the tube is 1.3mm ID. That makes for a rather loose fit but it worked well on the pond in windy conditions (most any design would likely work well on a windy day). We'll see how it works in our typical AZ day of 0 - 5 mph.

The horizontal component of the vane is a 5" 2 mm. CF rod. The fin is 2 1/4" along its base, 1 3/8" along the top and 1 1/2" high. The piece of putty stuck to the front of the CFR rod is to balance the vane. The mounting rod is bent at right angles and is about 5/8" on its horizontal section and raises the vane 1" above the mast. Vane mount

The mount on the mast is a 5.8" piece of aluminum tubing attached to the mast using a piece of carbon fibre tube with a sosmewhat smaller ID than the mast crane fitting. This results in the CF tube stanging out from the mast about 3/16". That, in turn, makes it possible to attach the small piece of putty (the white blob). The putty prevents the vane from blowing off the boat. The putty also allows for an easy removal of the vane. The bead is the rotating surface and sets the position of the vane above the mount.

### Replace the AA battery pak that comes with the kit with a AAA pak

The switch to a AAA battery pak lets you move down in battery size loosing weight in the process. There are many AAA batteries on the market. After looking a dozen websites related to battery capacity, I concluded that most, if not all, AAA batteries are just fine for our boats. It appears that the mAh rating of AAA's is about 1000 mAh. This leads me to the conclusion that a best buy battery is Costco Kirkland. If you can't get them on a particular outing to costco, it appears from my research that the duracell Coppertop is a good choice. And, they are available from Costoc, in my experience.

The battery pak shown in the image is from HobbyKing and does not have a connector. You have to add that. Buy a AAA pak from your local hobby store and they will, likely add a connector for you. The connector is a a JR servo female plug. You can buy the plug kits and add the plug to yourself. However, it is not easy. I have wired my own plugs a half dozen times and I am stil challenged by it.

## Add a foil streamer to the wind vane

PMYC skippers have been using a foil-like product as an addition to their wind vanes for years. The purpose of the stramer is to indicate the wind direction in the very lightest of wind conditions -- our most common conditions in So. AZ. I wanted to identify a product that would do the job. A few minutes of searching on the internet netted me a potential product at Michael's, here in Tucson. So, on the way to the pond today, I stopped at Micheal's (The Michaels Companies, Inc). After showing them the stuff I have been using they took me directly to their product. It is called CELEBRATE IT, Foil Tissue The package contains five sheets 20" x 26", enough to create streamers for over 200 boats. PMYC members get it for free for life. It came in what the product calls "teal' and "gold". I cut 3/16" wide, 7" long strips. A piece of tape attaches them to th wind vane.

A PMYC member has expressed satisfaction with the pieces of material froma cheerleading pom-pom from the Dollar Store.

## More choices with a better transmitter

For racing it is recommended that you use a somewhat better transmitter than the one identified in Step 7. The basic radio functions will not change no matter how much you spend for the transmitter. However, in my opinion, there is one transmitter feature that makes boat handling easier. That feature is commonly labeled Expo or Exponential in the transmitter setup. This feature (and others that come along for the ride) will bump the transmitter price up to around \$100.

The Expo function, short for exponential, lets you adjust the sensitivity of the control surface (in our case, the rudder) deflection around smaller TX stick movements. So, for example, you can set your rudder to barely move at all when you move the stick around its central position, but then go to full deflection when the stick is moved to its limit. Expo essentially calms down a boat that might otherwise be twitchy and over-sensitive to control inputs. A setting af about 80% significantly reduces the rudder response to the stick, a benefit when sailing close-hauled and directly down wind.

Travel Adjust - also called End Point Adjustment, and a few other names. This lets you set the travel limits of each servo, normally as a percentage of the servo's normal travel. The upper limit is typically 125% or so. Travel Adjust can be used to set or fine-tune control surface deflection limits, after all mechanical adjustment has been done.

Sub-trim - this sets the neutral point of each servo, and is handy if you can't get a control surface perfectly neutral with mechanical adjustment (on the linkages).

You will want a receiver that is DSM2 compatible for this transmitter. You can get a very low cost receiver from HobbyKing for \$5. Here is the link to the receiver link to the receiver.

Turnigy 9XR Transmitter (all items required) -- Price is about \$150 incl. shipping
---- Turnigy 9XR Pro transmitter
----OrangeRX DSN2/DSNX Transmitter Telemetry Module
---- LiPo battery
---- LiPo battery charger

Spektrum DX6i
This radio is very popular with model yachting and has been around for at least nine years. It can be found new and used. If you can find one used they make a good chouce for the model yachting.

Spektrum DX6e - About \$150 (not including the DSN2 Rx
Product review.

Product Review
Turnigy 9XR - Pro (from HobbyKing)
The Turnigy 9XR Pro is one of the most attractive alternatives to popular premium transmitters such as the Taranis X9D Plus which sell for over \$200. With an RF module and shipping cost factored in, expect to pay about \$150 to \$160 for the 9XR Pro. This is still roughly \$50 less than the Taranis.

With its versatility and compatibility with all kinds of popular radio frequencies (via RF modules), the 9XR Pro is undoubtedly a very attractive option for RC enthusiasts who are on a tight budget. It definitely has its flaws but its customization options more than makes up for this. There is also a wide range of accessories such as faceplates and six-way switches that allow users to customize their transmitters to suit their needs.

With that said, the 9XR Pro makes an excellent second transmitter if you already own a Taranis or Futaba. It’s also a great option for those who want premium transmitter features on a tight budget.

Website: Drone Files.
The Drone Files website
Product Reviewer

## Micro magic sail plan

If you make your own sails ail measurements must be within those specified in the image. If you cannot zoom in enough to be able to read the dimensions in this image, click on the image to load one that you can print.

## Make you own flat sails

Oct. 2017 -- This topic needs a knowledgeable source.

## Keel Tilt

This section was referenced in the earlier “Install the Keel” section. The purpose of this section is to address the subject of the tilt of the keel bulb and to explain how the bulb tilt was estimated and what was done to correct it. (Its original tilt was front down. The desired is the front tilt up 0 – 3 degrees relative to the rear of the bulb.

I placed this section at the end because unless you want to participate in inter-club regattas this topic is not of great importance. For PMYC club racing any disadvantage it may represent could be offset by good sailing and racing skills against all but the fastest boats.

Before getting into the details I have included the words from an email I sent to Greg Norris along with his response.

June 30, 2017 Jerry wrote to Greg Norris:

In you’re Model Yachting article you state that the mark on the bow “…just above the round area at the bottom of the bow”. However, the picture appears to be showing the mark near the bottom of the round area. To me this is where the mark needs to be – at the water line at the bow. That is exactly where the water line on my boat is.

June 30, 2017 Greg responded:

So, in light to moderate air I place the battery so that the transom is just kissing the water at rest, and I now make my keels with the bulb cant at 2-3 degrees upwards, or 87-88 degrees as you likely measure it.

What is truly optimal in a MM is however unknown.  Optimal bulb cant in a towing tank with an IOM is 3 degrees, with 0-2 degrees being very similar, but anything over 3 degrees upward or any negative (downward) can’t being much worse.  I know of no testing in rc boats in waves or under actual sailing.

1. Put keel in boat and gently tighten the nut.
2. Put a pencil mark at the bottom of the round of the round area at the bottom of the bow.
3. Put boat in stand on a smooth table.
4. Position the boat on the stand until the distance between the mark on the hull and the table and the bottom of the center of the transom are equal.
5. Measure the distance from the front and back tip of the keel bulb — the hypotenuse of a right triangle (130.5mm).
6. Measure the distance from the front and rear tips of the bulb to the table.
7. Subtract the two values. Hopefully, the front value will be larger than the rear. This is the Opposite side of a right triangle.
8. Calculate the angles using a calculus calculator such as CSGNetwork.com. One angle will be approx. 88, the other 2. You want the larger angle to be between 87 and 90 degrees.

After all of this be sure to read Greg Norris’ Summer 2017, Model Yachting article. or, read it here: http://pimamicroyachtclub.com/2017/04/27/building-micro-magic-gregg-norris-may-2017-model-yachting/

# PMYC Micro Magic Boat Building Materials

The idea of the boat building package is to provide builders with the stuff they need to build a boat that does not come in the kit and is less likey to be found in the garage or hobby room.

Items that it could contain include:

1. Ca – thin
2. nail polish
3. 50# fishing line for rigging
4. 15# fishing line for sheets

## Hobby Servo Tutorial

November 2017. I found this article at https://learn.sparkfun.com/tutorials/hobby-servo-tutorial while searching for an explanation for a “twitching” servo. It did not answer my question (I don’t think)  but I thought it a valuable addition to our rc experience and knowledge.

I have added it with out review as I do not have the time at the moment. I will review it soon and make needed fixes to make it easier to read.

Jerry W

________________

CONTRIBUTORS:  MIKEGRUSIN BYRON J.

### Introduction

Servo motors are an easy way to add motion to your electronics projects. Originally used in remote-controlled cars and airplanes, they now crop up in all sorts of other applications. They’re useful because you can instruct these small motors how far to turn, and they do it for you.

A typical hobby servo

You ordinary, small DC motor has two hookup wires and simply turns continuously when power is applied. If you want it to spin in the opposite direction, you reverse the power. If you want to know how far it has turned, you’ll need to devise a way to measure that.

DC motor (left) and hobby servo

In contrast, you instruct a servomotor where to turn using a command protocol. The servo has three wires – power and ground, plus a third wire, to carry those commands.

### Servo Motor Background

In the most generic sense, a “servomechanism” (servo for short) is a device that uses feedback to achieve the desired result. Feedback control is used in many different disciplines, controlling parameters such as speed, position, and temperature.

In the context we are discussing here, we are talking about hobby or radio-control servo motors. These are small motors primarily used for steering radio-controlled vehicles. Because the position is easily controllable, they are also useful for robotics and animatronics. However, they shouldn’t be confused with other types of servo motors, such as the large ones used in industrial machinery.

An Assortment of Hobby Servos

RC servos are reasonably standardized – they are all a similar shape, with mounting flanges at each end, available in graduated sizes, from “ultra-nano” to “giant”. Servos often come with multiple attachments, such as wheels or levers, known as “horns”, than can be attached to the shaft, to fit the device they are operating.

Example Servo Horns

#### Electrical Connection

Most hobby servos use a standard type of 3-pin plug, with the same control signaling, which makes RC servos reasonably interchangeable.

The connector is a female, 3-pin, 0.1″ pitch header. One thing that can be confusing is that the wiring color code isn’t always consistent – there are several color codes at play. The good news is that the pins are usually in the same order, just that the colors are different.

Servo Cables

The table below summarizes common color schemes. A useful mnemonic is that the most drab color (black or brown) is usually ground, and red is usually the power supply.

 Pin Number Signal Name Color Scheme 1(Futaba) Color Scheme 2(JR) Color Scheme 3(Hitec) 1 Ground Black Brown Black 2 Power Supply Red Red Red or Brown 3 Control Signal White Orange Yellow or White

Servo connection Color Coding

Heads up! If you’re in doubt about your color scheme, check the documentation – don’t plug it in backwards!

#### Control signal

The third pin of the servo connector carries the control signal, used to tell the motor where to go. This control signal is a specific type of pulse train. The pulses occur at a 20 mSec (50 Hz) interval, and vary between 1 and 2 mSec in width. The Pulse Width Modulation hardware available on a microcontroller is a great way to generate servo control signals.

Common servos rotate over a range of 90° as the pulses vary between 1 and 2 mSec – they should be at the center of their mechanical range when the pulse is 1.5 mSec.

pulse to position

#### Powering Servos

In RC vehicles, the nominal battery voltage is 4.8V. It will be somewhat higher after a charge, and it will droop as the batteries discharge. As the voltage drops, the available torque also drops – if you’ve driven RC vehicles, you’re no doubt familiar with the loss of control that occurs as the batteries get weaker. It starts to feel sluggish just before it dies.

If you’re not using batteries, the 5VDC available from a garden variety power supply is a good option. If you’re using an Arduino or other microcontroller (such as the SparkFun Servo Trigger) to control your motor, the absolute maximumsupply voltage that should be applied is 5.5 VDC.

Regardless of how you’re powering them, it’s worth noting that the current consumed by the motor increases as the mechanical loading increases. A small servo with nothing attached to the shaft might draw 10 mA, while a large one turning a heavy lever might draw an Ampere or more! If your power supply isn’t up to the task, a straining or stalled servo can cause the supply to sag, which may have other unpredictable repercussions, such as causing microcontrollers to reset.

Additionally, if you’ve got multiple servos, or in applications where the motors are moving non-trivial loads, it’s best to use heavy gauge wires and give each servo a direct connection to the power supply, rather than daisy-chaining power from one to the next. This configuration is commonly known as “star power.” If one servo causes the power rail to droop, it’s less likely to effect the others when each has a direct connection.

Star power.

When in doubt, grab a multimeter, measure the current consumed, and check whether VCC sags when the servos are turning.

#### Show Me The Guts

Internally, the mechanism of a servo motor uses a potentiometer attached to the rotating shaft to sense the position. It measures the width of the incoming pulse and applies current to the motor to turn the shaft, until the potentiometer indicates that the position corresponds to the incoming pulse width. This is a form of feedback control. The motor has received the desired position from the pulse width, and the actual shaft position is fed back to the circuit via the potentiometer. It compares the desired value to the actual value and drives the motor in the direction that causes actual to match desired.

Here are the insides of a servo that’s been dissected. You can see the gears, DC motor, position potentiometer, and a small PCB. The PCB has a chip on one side, possibly a small microcontroller or specialized servo IC.

Inside an RC servo

The other side of the PCB has some discrete transistors, probably in an H-bridge configuration, which allow the controller to steer current through the motor in either direction, for both clockwise and counterclockwise rotation.

Back of the PCB

### A Handful of Distinctions

When you’re shopping for servos for your project, there are several parameters that you’ll want to keep in mind.

### Range Constraints

The 1-to-2 millisecond pulse range is more of a convention than a hard-and-fast standard. Some servo motors respond to even shorter or longer pulses with an extended range of motion.

Be warned that there is a risk – this expanded range of motion isn’t universal. Some servos are mechanically limited to 90° rotation. Attempting to drive them beyond their limits can cause damage, such as stripped gears. The servo that we see dismantled here suffered exactly that fate.

The nub on the gear is used to constrain the range of rotation.

#### Position vs. Continuous Rotation

Moving even further from the 90° range, there are also full rotationcontinuous rotation, or simply 360° servos. As the name states, the shaft turns continuously, making them useful as drive motors. Visually, they look just like regular servos.

Look carefully, and you’ll notice the “360°” mark on the packaging.

Rather than controlling position, the continuous rotation servo translates the 20 mSec pulse-train signal into the rotational speed and direction of the shaft. Otherwise, they’re very similar to regular RC servos – they use the same power supply, control signals, 3-pin connector, and are available in the same sizes as RC servos.

The overall speed is relatively low – around 60 RPM is a common maximum rate – if you need higher rotation speed, servos aren’t the best fit – DC gearmotors or brushless DC motors are more likely candidates, but they aren’t directly compatible with servo control signals.

Nulling Trimpot

On closer inspection, continuous rotation servos have one small difference from regular servos: they usually have a “nulling” trimpot, used to adjust their response to the control signal. It’s typically set so that a 1.5 mSec pulse stops the motor. Shorter pulses will cause it to turn counterclockwise, and longer pulses cause it to turn clockwise.

#### Analog vs. Digital

The pulse-controlled servos we’re discussing here are analog. There are also digitally-controlled servos that use a high-speed pulse train, and have a serial communication interface that allows more detailed configuration, typically with parameters that are tailored to RC vehicles.

### Plastic vs. Metal Gears

One last thing to look at when considering a servo is the type of gears it contains.

Inexpensive servos (such as the one dismantled here) usually contain molded plastic gears, while more expensive servos have metal gears. Plastic gears are more likely to strip if the motor is jammed or overloaded. The old adage rings true: you get what you pay for.

Note the missing tooth at about 3:00 o’clock on the inner gear!

### Deploying Servos

As we stated in the introduction, the usual application of hobby servo motors is for steering radio-controlled vehicles.

RC transmitter (top left), with receiver and steering servo.

RC vehicles are controlled with a transmitter unit – the box with the joysticks and antenna. The transmitter sends control information to receiver modules (the orange box shown above), which connect to the servo motors. When the sticks on the transmitter are moved, the receiver generates corresponding pulses, instructing the motors to move.

Configuring older RC craft required a fair amount of patience, because adjusting the servos meant careful mechanical tweaking of the servo horns, mechanical linkages, and trim controls on the transmitter. Modern transmitters and receivers are microcontroller-based, tweaked through the LCD on the transmitter, or even a computer interface.

### Controlling a Servo with Arduino

Because they move on command, servo motors are an easy way to add motion to any project. If you’re working with an Arduino-compatible platform, the Arduino servo library provides a ready-to-go servo pulse generation solution.

#### Materials

To build this example, you’ll need the following materials.

ROB-09065
\$8.95
9

TOL-12889
\$5.95
14

### Jumper Wires Premium 12″ M/F Pack of 10

PRT-09385
\$4.50
1

DEV-12757
127 Retired

#### Hookup

Hooking a servo to a RedBoard is pretty straightforward. It only requires 3 connections.

Connecting a Servo to a RedBoard

In particular, notice that power to the servo motor is supplied from the `VIN` pin, which bypasses the onboard regulator. The onboard regulator in insufficient to drive anything but the smallest of servos. You’ll also notice that the project is powered with a 5V wall adapter. On the author’s workbench, performance was marginal when the board was powered by the USB port.

#### Firmware

With the circuit hooked up, load the following sketch.

Note: This example assumes you are using the latest version of the Arduino IDE on your desktop. If this is your first time using Arduino, please review our tutorial on installing the Arduino IDE.

If you have not previously installed an Arduino library, please check out our installation guide.
``````/******************************************************************************
servo-skatch.ino
Example sketch for connecting a hobby servo to a sparkfun redboard
(https://www.sparkfun.com/products/9065)
(https://www.sparkfun.com/products/12757)
Byron Jacquot@ SparkFun Electronics
May 17, 2016

Development environment specifics:
Arduino 1.6.5
******************************************************************************/

#include <Servo.h>

Servo testservo;

uint32_t next;

void setup()
{
// the 1000 & 2000 set the pulse width
// mix & max limits, in microseconds.
// Be careful with shorter or longer pulses.
testservo.attach(9, 1000, 2000);

next = millis() + 500;
}

void loop()
{
static bool rising = true;

if(millis() > next)
{
if(rising)
{
testservo.write(180);
rising = false;
}
else
{
testservo.write(0);
rising = true;
}

// repeat again in 3 seconds.
next += 3000;
}

}
``````

This sketch drives the servo back and forth.

Pay particular attention to the `attach()` call on line 26. It is using the optional `min` and `max` parameters, to constrain the pulses to the 1000 to 2000 microsecond (1 to 2 millisecond) range. As noted in the Range Constraints section above, driving a servo outside that range may damage the servo.

The Servo object can be a little bit confusing about the ranges and positions, particularly if the minimum and maximum pulses are defined in the `attach()` call. With the minimum and maximum defined, the parameters to the `write()` method (ideally expressed in degrees) get retranslated to the constrained range. In the example, `write(0)` will result in a 1 millisecond pulse, and `write(180)` yields a 2 millisecond pulse. On an average servo, this translates to approximately 90° of motion, not the 180° that the call parameters would indicate.

The servo library also has a few other limitations. Most notably, it overrides `analogWrite()`on pins 9 and 10. For more information about the library, check the Arduino reference pages.

If things don’t seem to be quite right, please look through the troubleshooting section.

### With the Servo Trigger

Having programmed a servo example from scratch in the last section, there’s another way to deploy servos that doesn’t require any programming.

The Servo Trigger

The SparkFun Servo Trigger is a small board dedicated to driving hobby servos. It has trimpots that allow you to set the servo positions and jump between the positions by actuating a switch. It is available in standard and continuous rotationversions. For more detailed information about the Servo Triggers, consult their respective hookup guides.

### Troubleshooting

Regardless of how you’re driving it, servos sometimes require a little extra attention to get working. Here are a few troubleshooting tips.

• Even unloaded servos can draw quite a bit of power. For full strength, you should be sure that your power supply can provide at least one Ampere per servo.
• When the power supply isn’t up to the task, servos behave poorly. They’ll move more slowly than a properly powered servo.
• Underpowered servos are prone to hunting, where they don’t move cleanly to the desired position, but instead move back and forth near that position. They might also audibly hum, or repeatedly reset.
• In some circumstances, when the servos and processor are running off the same power supply, the servos can draw so much current (or put so much noise on the line) that it may cause your processor to reset or misbehave. The simplest solution to this issue is to run your processor and servos off separate power supplies (but be sure to have a common ground between them). More complex solutions involve power supply noise filtering techniques; Google for advice.
• Powering your project via USB is only suitable for the smallest of servo motors. A medium servo easily exceeds the 100 mA available from a USB port.
• If your power LEDs flicker when you try to actuate the servo, you’re in risky territory!
• Servos have a maximum speed. If your servo is acting erratically, you may be trying to get it to switch from one position to another too quickly. Pausing between your commands gives the servo time to react.
• As mentioned in the Range Constraints section, some servos have different ranges of movement.
• When servos are driven past their end stops, they might hum, or grind their gears. Be careful if your servo starts clicking, a sign that the gears are binding.
• If this will affect your project, look for a servo that is specified to provide 180° of rotation. Also, note that the Servo library’s attach() command allows you to fine-tune each servo’s min and max position, to help avoid driving it beyond the limits.

Happy Servoing!

### Resources & Going further

#### Going further

• The Wikipedia article on Radio control Servos contains more more detailed information and history of servos.
• The uArm is a robotic arm that is driven by servo motors.
• You can hack a regular servo to turn it into a continuous rotation one.
• You can also remove the control board, turning a servo into a small DC gearmotor.

# Chores to finish the project

• Shorten the keel according to the manual on Page 9-20
• lubricate the rudder shaft
• Remove the text at the top of the doc.
• Neaten up the images at the beginning of the doc
• Snug up the keel nut.
• Keel/rudder slightly out of alignment.

## Index of Posts about Building a Micro Magic

Links to all of the items related to building a Micro Magic on this site

The information below identifies all of the posts/pages on the site that pertain to building a Micro Magic.

### Micro Magic Model Yacht For Sale in Tucson, AZ

March 30, 2018 – Micro Magic AVAILABLE for purchase \$325 This Micro Magic is available for sailing today. It has been sailed by several of

### Build a Micro Magic Model Yacht (2017 ARTR version)

The Micro Magic built from the directions in this post is for sale. Purchase this completed Micro Magic or use the instructons in this post to learn how to complete the building of your own Micro Magic almost-ready-to-race (ARTR) model yacht.

### Index of Posts about Building a Micro Magic

Links to all of the items related to building a Micro Magic on this site

### Perspectives on Building a Micro Magic – the Narrative

Producing a completed Micro Magic Radio Controlled model sailboat can challenge the mind, patience, and creative talents of an otherwise relaxed and rational individual.

### Perspectives on Building a Micro Magic – the Pictures

Building a Micro Magic model yacht. These are the images that go with the article

### Batteries for Your Micro Magic

Battery Variables It was easy to choose batteries for our Victoria’s. The preference was five AA batteries (approx. 6 Volts in a rechargeable battery or 7.5 V. in

### Review Graupner/SJ Racing Micro Magic Best. Nr. 2014.V2

This Post uses one of the links in the Building a Micro Magic – Greg Norris – May 2017 Model Yachting post. In the Building article it

### Our Documentation on Building a MM is Improving

For the complete set of MM building documentation that exists, as far as I know, about building a Micro Magic, click on the Model Yachting

### Building a Micro Magic – Greg Norris – May 2017 Model Yachting

Learn how to build a sturdy, light-weight, fast Micro Magic, whether you have one of the old German racing MM kits or one of the new Asian Graupner SJ kits.

### Build a MM – Product – Sails

Summary This post contains sail prices and will be updated as new data arrives. The products identified thus far are: Velas Velas Sails vamsails@vamsails.com https://www.vamsails.com

### Building a MM – Products – Tx and Rx

Receiver HobbyKing OrangeRx R610V2 Lite DSM2 Compatible 6CH 2.4GHz Receiver w/CPPM View the product details at the HobbyKing website and then bu y it from

### Building a MM – PMYC Members

This page holds the information and photos of the MM building experience of our members. The data is grouped by member. All contributions to our

### Building a MM – Products – Aids to Construction

Not everything you need to build your Micro Magic comes in the kit box. This needs work. It will contain the PMYC offerings for parts

### Building a MM – Email Exchange with Mike Eades & Greg Norris, Late March, 2017

This post, dated March 27, 2017, contains two email exchanges between Jerry Walker and Mike Eades of the West Valley RC Mariners (WVRCM) regarding the

### Building a MM – Model Yachting Magazine

Model Yachting Magazine Issue 159, 2010, Pat Buttersworth This article contains hints and ideas for building. This document was scanned from the magazine. It’s images

### Product Review – 2014 HoTT Micro Magic V2 Racing ARTR – 2017 production

By Mike Eades, MM #315 Back in 2015 the new Graupner SJ company had added an RTR version Micro Magic to its product range allegedly

### Building a Micro Magic – Purchase Sources

There are three sources for the Micro Magic. In each site, search for “micro magic”. I have asked Bill Brown to fill in the details.

### Building a MM – Email exchange between Jerry Robertson & Mike Eades of Litchfield Park

Mike is a well known model yacht racer of multiple classes, including the Micro Magic. This post contains the content of Jerry’s email exchanges with

### Building a MM – Associated Websites

Magic Micro Website Step-by_Step Instructions http://usa.magicmicro.org/f/public/1407421893_27_FT0_micro_magic_mk_ii_racing_step_by_step_assembly_instructions.pdf Micro Magic Parts List http://usa.magicmicro.org/f/public/1407421893_27_FT0_micro_magic_mk_ii_parts_list_with_pictures.pdf   Micro Magic International http://micromagic.info/ The British Class website is at: http://magicmicro.org/news.php. Graupner Graupner

## Perspectives on Building a Micro Magic – the Narrative

Producing a completed Micro Magic Radio Controlled model sailboat can challenge the mind, patience, and creative talents of an otherwise relaxed and rational individual.

(A Sudoku adventure in RC boat building)
by: Wm. Brown, Yeoman
Pima Micro Yacht Club,
Tucson, AZ

=======================================

View pictures of this boat while in development.

# The Challenge

The challenge comes from several directions. The finished product, however, is an extremely weight conscious and very finely tuned international racing machine. Being among the lightest of the competitive RC sailboats, the demand for
effective consolidation and distribution of weight, and, effective use of sails is critical. If these considerations aren’t enough, the kit presents itself with its own set of challenges.

Having built three Solings (10 Lbs) and two Victorias (5 lbs), I personally found the Micro Magic (2 lbs) the biggest and most rewarding challenge. Yes, completing my boat, was fun.

# The kit

The kit, first developed and manufactured by Graupner in Europe, comes
with a number of notable challenges. The hull and deck are fabricated from a fairly “soft” and flexible ABS material. The two components are brittle to impact and subject to distortions from inappropriate glues. More on that later. The challenge of effectively bringing together the hull and deck is formidable, and, is not appropriately addressed in the kit instructions. At the Micro Magic National Competition in Phoenix last Fall, I observed that deck / hull union was apparently a source of frustration for more than one competitor. The kit itself comes with very limited step by step construction dialog. Full size schematics, however, are good and complete. A word of caution regarding the alignment dimples on the deck and hull, … ignore them. My rudder was 12+ degrees off vertical, and required my cutting an unscheduled hole in the aft deck. The keel deck hole was too small and was 1/8 in. off center line. The stern deck / hull alignment was off 3/16 inch. Other smaller kit “discoveries” included: the main and jib booms being a little short for effective sail outhauls, and, the hatch closure being poorly designed, misaligned, and not user
friendly. The most important issue not addressed in the kit instructions deals with effective placement of batteries. Being the heaviest single item in the boat, battery location deserved a more thorough discussion.
A critical eye and common sense caught a majority of the kit’s shortcomings. On the positive side, the kit provides an array of opportunities for creative and rewarding problem solving, ….I found it the fun part of building a Micro Magic.

# Construction Considerations

Get ready. I hate bowsies! In this discussion you will note that I favor the use of a proven alternative. For the purpose of securing cordage, I have opted for the use of 3/16 in. nylon machine screws. Where used, a slightly enlarged 3/16 hole is drilled into the appropriate location and a nylon nut is epoxied to the underside. Using a small screw driver, cordage is adjusted and secured under the head of the machine screw. After
five boats and no failures, I enjoy this simple arrangement!

# Let’s Build the Boat

## 1. Selection of glue

Prior to starting construction, I took five pieces of scrap ABS
from the kit and tested the adhesive and thermoplastic qualities of three glues and four epoxies. Glues included Super Thin CA, Thin CA, Gap Filling Medium CA, and Shoe Goo. All appeared safe to use, but, Medium CA, with prep sanding, proved to have the best tensile adhesive quality. Shoe Goo didn’t make even a decent filler. Medium CA worked very well on both ABS and Carbon Fiber (CF). Two part epoxies included Devcon Plastic Welder, Ace Plastic repair, Loctite Extra Time Epoxy(60 Minute), and Loctite Marine Epoxy (two hour). With prep sanding, CA and Loctite epoxy worked very well on the deck / hull union. Medium CA was flowed between the deck flange and hull and Marine epoxy used for gap filling. All the above, especially the Loctite Marine epoxy, sanded and finished very well. A review of the literature reveled that some glues have proven to be too “Hot” for ABS. Caution should be taken.

## 2. Deck/Hull Union

When bonding the hull to the deck, the challenge is to effectively push the hull out and against the 5 mm deck lip, ie: flange. The non rigid hull does not uniformly align against the deck flange. My solution was to create a 5 mm deep X 3 mm wide trough on the bottom (inside) surface of the deck. This trough uniformly forced the hull wall against the overhanging deck flange. Using of lots of close pins, the fence was uniformly pre-positioned and glued 3 mm inside the deck flange. Medium CA was used for bonding. (See Photograph) With the fence in place, the hull wall was prep sanded, placed in the trough, and secured with compression rubber bands and tape.(See Photograph). Medium CA was flowed into the trough to complete the union. With the edge of a finger and Marine Epoxy for filler, a uniform, strong, and esthetically smooth bead of epoxy was laid down between the hull and flange.

## 3. Jib boom weight Management

Rather than simply attaching the jib boom weight to the leading end of the jib boom, I elected to: (1) cut the head off a small 3/32 in. threaded brass bolt, (2) and insert the bolt into the forward end of a non kit 4mm DIA
CF boom, and (3) apply medium CA to secure the bolt in place. I then tapped the kit brass jib boom weight to match the bolt thread. This created a fore and aft adjustable jib boom weight. (See Photo.) The weight was secured in place by a like threaded nylon nut.

## 4. Forestay to the jib boom Attachment

The forestay, coming down from its pivot point on the upper mast, is attached to the jib boom using a small 1/8 in. dia. split ring. The ring was placed on the aft end of the threaded screw described above (#3). This
arrangement is very simple, very accessible, and very removable.

## 5. Boom to deck Attachment

My goal here may appear to be making the attachment as complicated as possible. But, not so. The attachment actually is a response to several controversial goals.

Goal #1: Get the boom as close to the deck as possible;

Goal #2: Make the boom height off the deck adjustable;

Goal #3: Reduce tension, friction, and torque in the short cordage between the jib boom and its deck attachment.

Solution:

(1) Make the cordage longer (from 1/4 in. to 1 1/4 in.),

(2) secure the cordage to a point below the deck,

(3) for adjustment, return the cordage to a point above deck. Using 3/16 in. dia. styrene tubing, continue the angle of the jib boom stay through the deck, around a 3 in. radius, and returned the loop to exit the deck 3 in. behind the entry point. In this water tight tube, the tension, friction, and torque of the stay is distributed over both a longer distance and a longer piece of cordage. After exiting the hull, the stay (now a halliard) is taken to an adjustable machine screw located at the base of the mast (See opening preface). Note: The length of the jib boom halliard is now adjustable, and, the stress on the cordage is greatly reduced. This a

rrangement provides quick adjustment of both boom height off the deck, and, in conjunction with the back stay, the fore and aft tilt of the main spar (mast). Using a small screw driver, both adjustments can quickly be made when there is a change in wind speeds.

## 6. Back Stay/Transom Attachment

I opted for:

(1) an 8 in. piece of cordage anchored on the transom,

(2) extending this cordage up to a 1/8 “ split ring on the backstay, and

(3) returning the cordage down to the transom. The return cordage is secured on the transom under the head of a nylon machine screw (see Preface). Sounds complicated, but, it makes for a very simple adjustable backstay. With the twist of a screw driver, you are ready for adjusting and securing. No bowsies.

## 7. Topping lift and forestay Adjustment

Note: The way I elected to configure these two items, would traditionally make them halliards; i.e.; Both pieces of cordage attach to a moveable item, follow a course up the mast, and then return to the deck. The common mast top return for both halliards is located approximately 27 in. up from the bottom of the mast. Returning to the deck, these halliards are secured under two very adjustable nylon machine screws (see Preface and Photo). To achieve a horizontal line to the screw heads, a 1/4 in. high X 3/4 in long deck fence is CA’d to the deck near the nut heads. The cordage (halliards) is passed through two 1/16 in. holes in the fence to the screw head. Again, a small screw driver affords the opportunity to adjust and secure these two halliards. No bowsies.

## 8. Battery Weight Management

This is a biggie! The battery in the MM is the heaviest single component in this two pound boat. In the five pound Victoria or the 10 pound Soling, the placement of the same weight is important, but, not as critical. The dilemma: How can you maximize the fore and aft tuning of the heaviest object in the boat? Ideally you would like to be able to move the battery to any location between the rudder post and the keel trunk. If this could be accomplished AND position the two servos in line with the battery, you could achieve ideal beam to beam and fore and aft weight symmetry. The heaviest items in the boat would be as low as possible in the hull, aligned amidship, and be adjustable.

A Solution: (1) Make a tunnel under which the battery can slide from the rudder post to the keel trunk, (2) mount the servos in line on top of the battery tunnel. The lateral weight symmetry for both components would be ideal.

Fabrication: The tunnel is fabricated from three pieces of 1/16 in. Lexan. Lexan is a premium, poly-carbonate and can be purchased at Lowes in 12 in. squares. The tunnel has a 5 X 2 in. top and two lateral walls 4 X 1.5 in. The walls are angled out from the top at 30 degree angles. The three components are bonded with Med CA. Two identical Hittec HS-5085mg servos are mounted end to end on the top of the tunnel. The battery, resting on the floor of the hull, fits comfortably under the servos. Lateral shifting of the battery is controlled by two 8 X 3/16 in. fore and aft, styrene “fences”. These battery guides are CA’d parallel and 3.75 in. apart inside the hull wall. The width of the “trough” is dependent upon the width of the battery plus about 1/4 in. on each side. In this trough, the battery pack should move freely from the rudder post to the keel trunk. The battery / servo tunnel may be secured to the hull floor by whatever means you wish. I enjoyed the use of small conveniently located nylon machine screws. A nice feature of the tunnel concept is that it is totally removable from the boat, …servos, servo arms, and battery. Tuning battery fore and aft: Note: don’t get lost here, – this really is simple. First determine the direction and posture you would like your battery pack to rest, – while under the tunnel. The direction and path of the battery leads going to the receiver must be given consideration. Once the position of the battery in the trough is determined, CA a piece of string to the aft (rear) end of your battery pack. Then CA a piece of string to the forward end of your battery pack. Next, fabricate “returns” for these strings from 12 in. squares of scrap ABS. Drill a 1/16 in. hole in each return. CA one return near the rudder post and the other to the side of the keel trunk. Thread the aft battery string through the rudder post return and the forward string through the keel trunk return. With the battery tunnel secure in the hull and servos installed with arms attached and sheeted, bring the two battery tail strings up and over the tunnel and tie them together. You now have a loop that: pull one string and the battery will glide back, pull on the other and the battery pack will glide forward. With a nylon machine screw anchored on the top of the tunnel, you can secure or release the ends of the loop and position your battery in an infinite number of fore or aft positions. The servos remain anchored and in line on top the tunnel. The servo arms move free and un encumbered.

## 9. Aligning the rudder post

Caution: Do not use the dimples on the deck to align your rudder.
The goal here is simple: Make the rudder and keel perpendicular to the deck.

Accomplishing this is not challenging. Start by moderately oversizing the rudder post hole located on the cockpit floor. With the brass rudder post through the hole in the hull and extending up and through the oversized hole on the cockpit floor, slide the rudder into place. Put a block under the rudder to prevent it from falling out. This support will be used to tune the alignment of the rudder fore and aft, and, beam to beam. Next, place two identical small square pieces of wood on the deck edge (the gunnels) on each side of the servo access port (hole). Bridge, beam to beam, the two pieces of wood with an 8 or 10 inch bubble level. With the boat hull in it’s cradle and rudder independently supported, view the level from behind (astern) and level the deck. Next, drop an overhead plumb line and bisect the boat transom. With the deck bubble level leveled, the line will be perpendicular to the deck. The plumb line provides a visual reference for aligning the rudder and rudder post – beam to beam. To align your rudder post vertically (relative to the cockpit floor), place your level fore and aft on the cockpit floor and raise or lower the hull bow to achieve bubble level. The rudder and rudder post are now vertical, – beam to beam and fore and aft. Using the cockpit floor, It is now time to slip the snug fitting ABS collar over the brass rudder post tube, and, with CA, “lock in” your alignments. When dry, remove the rudder from the rudder post. With a mirror and a piece of wire, apply marine epoxy around the two in-hull rudder post exits. Reinforcing these two stress points will protect the hull from the brittle nature of ABS. With the rudder post now solidly secure, use a fine metal file or drummer grinding disc, carefully hone the lower brass tube rudder housing flush to the hull. Leaving 1/16 in. extending from the cockpit floor, perform the same procedure on the upper end of the brass tube rudder housing. It is now time to trim the upper margin of the rudder. This margin should duplicate the contour of the hull. Installed, the movement of the rudder from side to side should clear the hull by the thickness of a piece of paper. The cockpit rudder servo arm should move smoothly from side to side and be parallel to the cockpit floor.

# Observations/Suggestions

1. As noted, the ABS hull of the MM is brittle and vulnerable in impact situations. My hull came in a new box with a 8 mm crack on the bow, – at about the water line. A packet of accessories was in the immediate area. I resolved the problem with a 1in. X 2 1/2 in. piece of single ply, medium fine, fiberglass. The patch was laid vertically inside the bow and bonded with slow setting, two part, marine epoxy from Ace Hardware. A very small external cosmetic application of the epoxy resolved the problem. Surfaces were prepped by a light sanding. This relatively simple procedure was also performed at the junction of the keel box and the hull. To avoid future impact problems, I suggest following this procedure when constructing any Micro Magic.
2. As noted, I personally enjoy using small nylon slotted machine screws and epoxied nylon nuts to secure, (1) the main and jib sheet length adjustments in the cockpit, (2) the back stay adjustment on the transom, (3) the jib toping lift and forestay halyard adjustments, and, (4) the jib boom deck adjustment.

3. When binding the deck to the hull, there is a transition issue where the 90 degree deck flange stops and the slope of the aft deck to the transom starts. If nothing is done to reinforce this deck / hull transition, you end up with an unreinforced 90 degree hull to the deck glue job. Not good !! I opted to continue my styrene “fence” (see Deck / Hull Union above) through this transition, and around the inside margin of the transom. Taping the deck and hull together and then flowing medium CA between the fence and hull provides a much more stable union. Cosmetic filling was accomplished with slow setting, two part, marine epoxy and fine
sanding.

4. My main spar (mast) is unstayed. If, however, you wish to incorporate standing stays, I suggest not using the items provided in the kit. Glue failures are common. I and others suggest the following: 1. Make a 1/2 inch round disc from scrap kit ABS, 2. Drill a 1/16 in. hole in the disc, 3. Stick the head of a small cotter pin through the hole in the disc and flair the legs of the pin out and flat, 4. Epoxy the flared legs to the bottom side of the disc, 5. Drill a 1/16 in. hole through the appropriate location on the deck, 6. From the bottom side of the deck, stick the head of the cotter pin through the deck, then, 7. With the head of the cotter pin protruding through the deck, CA the top of the disc to the bottom side of the deck. On the deck top, use marine epoxy to cosmetically finish the area around the protruding cotter pin head. If this arrangement fails, you have demolished the deck of your boat and the boat will soon be resting at the bottom of the pond.

5. Reducing drag. Drag and friction are speed killers.. Sailboats are unique, – they interact with two media, air and water. Separately or jointly, both have the potential of producing significant friction or drag. Air we manage and control with sails, hulls we manage by fairing the trailing edges of the rudder and keel. The trailing edge of each of these components should be
sharp, able to cut paper, ….or at least cheese. Another form of drag is surface tension and / or turbulence. Researchers have demonstrated
that very finely sanded (400 grit or more) and unpainted surfaces have less friction than shiny painted surfaces. Most of RC boaters do not paint below the waterline. They keep their keels, rudders, and hulls micro sanded and very clean.

6. Painting suggestions: As noted above, painting below the water line is not recommended. Micro sanding and painting above the water line, however, is both fun and provides visual identification of your boat. Prep sanding with 300 – 400 grit paper and using Krylon Fusion (for plastic) has been successful for most in our sail club. Care should be taken to maintain the recommended 12 -14 inch distance from the hull, and allow an average of 1 hour drying time between thin applications. Thoroughly mix the contents of the spray can. If your finish “corn flakes” on you, let it dry, sand it smooth, and, start again.

7. Mast Options: I elected to use an unstayed, 6.0 mm OD / 4.8 mm ID, 28 in. long, carbon fiber mast. I fabricated an aluminum mast crane. To prevent the CF from vertically splitting, I found it necessary to tightly wrap the mast head with fine cordage and glaze it over with epoxy. The forestay and toping lift halliard return is located 26.75 in. from the bottom of the mast. With two holes in it, the small piece of 1/4 in. thick Lexan is contoured to the mast and secured with medium CA. The bottom of the mast is plugged and glazed with epoxy.

8. Boom options: I elected to use 4.0 mm DIA hollow CF tubing. A small cotter pin inserted and CA’d in the back of both booms provides a good outhaul attachment.

9. Sail options: A review of the literature strongly suggests purchasing custom sails.

10. Wet Tuning. When completed, Micro Magics’ small size makes it ideal for putting it in water and noting it’s resting “posture”. Using a plum line and viewing the mast from behind, you can accurately determine if the completed model sits flat on the water. A mast that is not vertical will respond differently on port and starboard tacks. Viewed from the side, the plum will tell you the amount of fore and aft rake present in the mast. As noted earlier, correlating mast rake with battery location in a two pound boat is critical.

# Closing

I hope this information provides some insight into the fun you can have creatively solving problems. On the pond, this jewel of a boat will let you celebrate both your imagination and your ingenuity. It has for me.

## Perspectives on Building a Micro Magic – the Pictures

Building a Micro Magic model yacht. These are the images that go with the article

[tov]

May 24, 2017

Bill Brown’s MM finally went in the water today. Here are the many pictures he has provided as examples to future builders. Of course, he is always available to give help to anyone asking.

Bill’s email is: wmmb1231@comcast.net

These pictures go along with his description of his experience. See Bill’s “Perspectives on Building a Micro Magic – the Narrative”.

The pictures and narrative will be merged at some point.

## Battery Variables

It was easy to choose batteries for our Victoria’s. The preference was five AA batteries (approx. 6 Volts in a rechargeable battery or 7.5 V. in a standard battery), though a significant number of our skippers elected to use four cells (approx. 4.8 V. in a rechargeable battery or 6 V. in a standard battery). The argument for five cells is faster servo movement and increased servo torque, both a boat performance benefit.

Whether you are using four or five cells there is another parameter to be kept in mind. That is the ampere hour rating. An ampere hour (abbreviated Ah, or sometimes amp hour) is the amount of energy charge in a battery that will allow one ampere of current to flow for one hour. So, a milliampere hour (mAh) is 1000th of an ampere hour. As a practical matter the mAh value determines how long a device will run before the battery needs recharging. In the Victoria, I typically used 1500 – 2000 mAh batteries. This guaranteed that I could sail the boat all day on one charge.

A quick divergence. Standard, non-rechargeable, batteries are 1.5 Volts each. Some of our skippers used 4 standard batteries in a container with complete satisfaction. As far as I know, one cannot purchase five cell containers.

## Micro Magic Batteries

The Micro Magic ready-to-sail weighs less than one-half the Victoria (860 gm or about 31 oz., less than 2 lb.). The most c

ommon battery selection is five rechargeable AAA’s of about 700 mAh. According to Mike Eades, this will provide several hours of racing time. His view is to use this low mAh battery and change it out during the lunch down time at a regatta. My 800 mAh pak weighs 66 gm., about 2.4 oz. After the pak was assembled and shrink wrapped by Batteries Plus, I sealed all openings with silicon seal to keep the water out.

The following is the configuration and weights of my battery paks for reference. Obviously, the most significant weight variable is the number of cells. But, also n

otice that the weight is also associated with the mAh rating.

5 Cell, 800 mAh AAA = 66 gm (2.37oz) (this is the 5 800 mAh battery pak shown above)

4 Duracel, 1150 mAh AAA in a plastic battery container = 54 gm (1.93 oz)

5 cell, mAh unknown AA = 133 gm. (4.75oz) (my guess on the apparently low weight is lesser mah rating)

4 cell, 2000 mAh AA = 120 gm (4.34oz) (I have two paks at this weight; both Batteries +; so no surprise)

Note that the 5 cell AA weighs 133 gm while the 5 cell 800 mAh AAA weighs 66 gm, a 2.4 oz difference.

## Batteries for Battery Paks

My new battery pak for my Micro Magic is composed of five tabbed batteries I found on the Internet. Tabbed batteries make it easier to assemble paks. I started my search for cells wanting Panasonic Eneloop’s. I could not find them. Next I investigated tabbed batteries from any source. The image to the right shows the typical battery appearance that I found. Though t

he mAh rating was given, there was no information upon which to make a quality judgement. Somehow, I

made the decision to purchase them from QRW Solutions on Amazon (Duh! Where else?). Like I said previously, quality unknown. I purchased six cells; the company sent me seven (i hope that isn’t an expression of their expected quality). My total cost was \$10.

## Battery Tabs

I have constructed a battery pak using short pieces of wire

as “tabs”. One soldiers the wires to the batteries, preferably using a soldiering gun as it can product high heat very quickly. High heat applied for a second to properly prepared batteries does the job without damaging the cells. Using wire connections is not desireable. It took too long to deal with each soldier joint as the wire wanted to fall off of the battery. There are three choices to this subject if you want to prepare a pak. Buy tabbed batteries, buy the flat pieces of metal shown in the red-background image, or buy tabs with holes as shown in the other image.

Based upon my experience, the first choice is the easy way to go, whether you assemble the pak yourself or have Batteries Plus do it. The second choice is the tabs with the holes. Based upon videos I have watched on the do it yourself approach, they look like the easiest to me.

I asked the folks at Batteries Plus about their opinion about the best AA, AAA batteries. It was Sanyo and Samsung at the top. This needs to be investigated, because when I did a “best aaa battery” i did not see these companies.

Note: all weights were taken on my kitchen scale. I know it is not exactly correct, but for our purposes here it is sufficient.

## Review Graupner/SJ Racing Micro Magic Best. Nr. 2014.V2

This Post uses one of the links in the Building a Micro Magic – Greg Norris – May 2017 Model Yachting post. In the Building article it is identfied as an article comparing the v1 and v2 MM. The link appears in the Introduction section of the post.

It is included here to provide an easier to find the article.

You can print the article from the Greg Norris post. See above.

## Our Documentation on Building a MM is Improving

For the complete set of MM building documentation that exists, as far as I know, about building a Micro Magic, click on the Model Yachting Magazine Category.

If you want to print an article, you will have to click on its title; taking you to a place where only the one article will appear. At that new location you will see the Print icon appear under the Post title.

## Building a Micro Magic – Greg Norris – May 2017 Model Yachting

Learn how to build a sturdy, light-weight, fast Micro Magic, whether you have one of the old German racing MM kits or one of the new Asian Graupner SJ kits.

# Building a Sturdy, Light, and Fast Micro Magic

by Greg Norris in close collaboration with Ralf Bohnenberger and Jack Chambers

## Meet the authors

Ralf Bohnenberger is one of the leading German Micro Magic skippers and he’s very active on the in MM International website.  He’s a

n engineer and an excellent modeler.  His boats are very well built and full of good of ideas. He would not dream of sacrificing complexity for simplicity.

Jack Chambers is one of the Azura MYC MM skippers.  He is actually very new to sailboat racing.  However, he used to make wind tunnel models for a living and he now builds gorgeous RC-gliders from scratch.   His mode is over the top perfection.  His favorite noun is Reynold’s number and he studies aerodynamics as a hobby.

Greg Norris (no picture) is an ok MM racer, also out

of the Azura MYC, who is also the US class secretary.  He is an adequate modeler.  He is into light, sturdy, fast and bright colored.  He doesn’t spend much time with pretty or very cool, even less with complexity or perfection.

Note:  All photographs are by Ralf Bohnenberger and Greg Norris.

## Introduction

In this article, we will show you how to build a sturdy, light-weight, fast Micro Magic, whether you have one of the old German racing MM kits or one of the new Asian Graupner SJ kits. For the rest of this article, we will refer to the old kit as v1 and the new one as v2.  If you happen to have a v2 Carbon Edition kit, we will discuss that as well.

If you are going to build a Micro Magic, you will rather quickly note that the directions that come with the kit are not exactly what you had in mind, no matter what it was that you actually had in mind.  Happily, the instructions seem to be slowly improving and there’s lots of other help:

You’ll want print out and read Peter B’s parts list and build instructions.  These are old, but the pictures, order, and overall instructions are excellent.  They are tailored to v1s, but most of it is at least very similar with v2s.  [http://usa.magicmicro.org/p/forum/forum_viewtopic.php?2452]

Then you’ll want to look at two articles on the MM International site:

Ralf has a piece where he very carefully compares the then new (2014) v2 to the v1. Interestingly, this article morphs into an early v2 build article.  [http://micromagic.info/wp-content/uploads/2016/02/Review-Kit-rMM-2014-V2-English.pdf]

Separately, there is a nice short piece on how to make a v2 boat class legal.  Read this if you are interested, but both of our boats will be class legal and we will discuss and make all of the (minor) adjustments necessary to do this.

Lastly, we will build two fast, sturdy, simple boats, but we’ll have plenty of pictures of Ralf’s beautiful work if you are inclined to the really cool, as well as pictures of Jack’s artwork if you are artistic and like really slippery stuff.

Instead of giving supplier information throughout the article, there is a supplier list at the end of the article.

## v1 and v2

One thing that we will not be discussing are the pros and cons of the various differences between v1s and v2s.  You can read about that in Ralf’s link above, though I would stress that v2 MMs are steadily improving, and the kits that we are building now are a good bit nicer than the very early one he reviewed in his piece.  The most important thing to know about the relative performance of v1s and v2s is that at the 2016 MM European Championship v2s won and came in 3rd, while a v1 came in second.

Right out of the box both kits look great.  The v2 is of slightly thicker ABS than the v1, but more importantly, in places where the material is pulled thin by the mold (bow, bottom of the hull) the v2 feels noticeably sturdier.  The weight of the hull, deck, keelbox, and hatch is 208 grams on the v2, 185 on the v1.

The bulkheads and strengtheners on the v2 are mostly ABS, plywood on the v1.  And they used to come glued in place, but more recent versions have some plywood pieces and aren’t pre-glued.  Just play that by ear.  I’m really happy that the v2 kit seems to be under slow, steady continuous quality improvement!  You’ll also note that we don’t use many of the strengtheners on either the v1 or v2.  Actually, if Ralf had his way, we’d have used almost none of them.

## Rudder Post

The first step on the v2 is to drill the hull rudder post hole.  It goes 210 mm from the aft edge of the keelbox, measured on the bottom side of the hull and centered with calipers.  Remember that the ABS grabs drill bits badly, so start with a small bit and work up to the final size.  Ralf says that you only need the rudder post reinforcements if you are an amateur.  Well then call me an amateur.  I used the bottom one, but agree that the top one is not important.  There is no reason to drill the deck rudder post hole now.  It’s easier later. Now glue the rudder post reinforcement in place.  When dry, drill out the hole until the rudder post can be inserted easily.  Then put the rudder post aside.

## Glues

And it’s a great time to talk about glues:  ABS to ABS you should use an acetone based glue.  I screwed up and missed an early tip from Ralf to use Uhu Plast Special (hereafter “Plast”).  Instead, I used Testor’s model cement and it was very much less “hot” than the European stuff that I’d used previously. For wood or brass to ABS, as well as for ABS to ABS when I couldn’t clamp well, I used a German epoxy not available for purchase in the US – Pattex Stabilit or Uhu Acrylit (hereafter “Stabilit”). It’s clamp time is about 10 minutes, which means that you can hold pieces in place while they are drying when clamping is hard.  And the bonding of whatever to ABS is fabulous.  Highly recommended.  Just a reminder:  be sure to rough up any surfaces being glued with 100 grit sandpaper, then clean them with naphtha (lighter fluid) prior to gluing.

## V2 Carbon Edition Kit

And it’s also a great time to discuss the v2 Carbon Edition kit.  These boats look really trick.  They are transparent ABS with carbon fiber looking paint on the inside.  Assembly is identical to the usual kits, except that you need to sand off the CF paint at all glue junctions.  You’ll be thinking that this will screw up the look, but really it’s just a great opportunity for some really cool racing stripes.

## Keel Box

Glue the keelbox together with Plast and clamp till dry as in the photo. Glue the mast ram reinforcements to the keelbox with Plast on

the v2, Stabilit on the v1.

Glue in the keel box with stabilit.  Just hold it down and in place till the glue hardens.  Be sure to get the stabilit under the little lip on the hull and cover lightly over the edges from above as shown.

## Sail Servo Holder

If you’re building a v1, use the plywood sail servo holder provided, but cut away the plywood on the right intended to hold on a jib servo (which is not class legal).  On the v2 you’ve likely got some choices.  In my kit, I received a plywood servo holder and two plastic ones.  All three were too flexible.  I could have glued two of them together, but instead I just cut out a copy of the plywood one out of 1mm CF plate.  Looks trick and is very light and stiff. (Be sure to wear a mask and eye protection when working with carbon fiber!)

Or you can copy Jack’s work of art (DSCN8268)

v2 style rudder servo plates (DSCN0102).

## Rudder Servo Mount

The rudder servo mount on the v2 is really trick. If you’re building a v1, just make a copy of the v2 version out of 1 mm CF plate, a piece of thin plywood or some spare plastic (like an old credit card).  I liked the CF one I made for the v1 so much that I made another for the v2.  That was unnecessary though.  The stock plastic one is fine.  Since it was CF plate, I glued this on with Stabilit.

## Bow Reinforcement

Concerning the bow reinforcement, you need to make a choice, but you can’t really make a mistake.  Take a look at the diagram below.  This is how Ralf fastens his jib boom to the deck.  It is ultra-cool and saves a gram or two.  Alternatively, you can just use a cotter pin glued to the deck as in photo x (No photo).  Both methods work fine.  But if you opt for the cotter pin, I think that it’s better to include the bow reinforcement, since

this gives a much greater area to glue the front of the deck to the hull so that the tension on the jib boom doesn’t separate the deck from the hull.  Since both of these boats will sail out of the Azura MYC and all Azura rigs use the cotter pin method, we opted for this.  But for most new builds I think that Ralf’s method is a better choice.

To the right are the deck layouts for the v1 and v2.

## Hatch and Power Switch

Now glue in the little blocks to hold the hatch fasteners in place.  Ralf doesn’t use them, he tapes his hatch in place.  But he also uses a cool magnetic power switch for the hull electronics.  I don’t bother a switch.  (A 700 mAh battery will easily get you through half of the longest full race day without any switch at all.  Just change batteries at lunch.)  You decide.

## Reinforcements

I did use the transom braces.  Actually, after I destroyed the v2 transom brace while trying to lighten it, I made a new one out of 1mm CF plate.  I liked it so much that I made one for each boat.  This is however unnecessary.  The kit ones are fine.  We did not use either of the big main bulkheads on either boat (more about that further down).  You do not need the stern deck reinforcements.  Glue a ~1.5mm cotter pin in place for the backstay using Stabilit and similarly glue your bracing and hook or your bracing and cotter pin in place for the jib boom attachment.  The hook/cotter pin should be 176 mm from the center of hole for the mast.  On the v2 ignore the dimple on the deck.  It is in error.

If you’re planning to use the cotter pin method for the jib boom deck hook, the reinforcement for the little screw should be 65 mm in front of the center of the hole for the mast.  You do not need to use the entire deck reinforcement piece for either method.  You will not need side stays, so leave out the reinforcements, and indeed if there are any other reinforcements that we’ve failed to discuss, leave them out.  Finally, varnish any wooden reinforcements with a single coat of varnish.

You will have noted that I glued some sponges in place.  I think that it makes no sense to have water sloshing around the boat when sailing in heavy air.  Also, I built a little two-walled house to catch the aft end of the battery slider.  It is made of 2 pieces of 1mm CF plate and a roof of 0.3mm CF plate.

## Glue the Deck

Now it’s time for the most exciting part of the build!  We are going to glue the deck onto the hull.  First, trial fit carefully.  This is simple:  you want the hole for the mast on the deck to snap into place in the keelbox.  On a v1, this means that you’ll need to trim away a little of the flange in the bow, since otherwise the deck will sit about 2 millimeters too far forward.  On the v2 the deck fits pretty well right from the start.

In Peter B’s build article, he uses a bunch of rubber bands as his clamps.  I like masking tape better.  Either way, be sure to practice mounting the deck to the hull about 5 times before actually using any glue.  Also, be sure to cut all of your masking tape strips prior to gluing.  I

used Stabilit at the keelbox/deck junction and if you used the cotter pin method for the jib boom attachment, use it at the bow reinforcement/ deck junction as well.  Use Stabilit in the transom area for sure, but do this as a second step after the hull flange/deck junction is all done.  I use Plast for the whole long hull flange to deck junction.  Be sure to drill the holes in the deck for the mast ram as well as matching starter holes in the keel box.  You will need these for clamping the deck to the keelbox when you glue the deck on.

So, now quickly apply a moderate (not thin) amount of Stabilit to the top of the keelbox (and if so planned, to the bow reinforcement) and a similarly moderate stripe of Plast to the whole long hull flange and to the bottom of the deck where the two will mate. Press everything together as previously practiced, then quickly apply all of your masking tape strips and screw the deck to the keelbox with the two little mast ram screws.  I let it dry like this for 12 – 24 hours, deck side down to avoid drips.

Remove the tape.  Check carefully that all areas are bonded well.  It you find areas where the flange moves against the deck when you squeeze the hull together, fill these with Plast and allow to dry.  Don’t use too much or you’ll melt the gunwale.  After everything has been dry for a day or two, I apply a ring of thin CA glue all around the gunwale to assure that all is well glued.  Ralf and Jack don’t bother with this, since their work is of higher quality initially.

After the gunwale has been dry for over 24 hours, glue the rear quarters and transom with Stabilit.

You will note that on the v1 that the hull sticks out about 1 mm

further than the transom.  On the v2 it’s more like 3mm.  Almost everyone sands the v1 flush.  I have psychological issues with shortening waterlines, so I left the v1 step intact, tiny as it was.  On our v2, the hull was about 3 mm longer than the transom.  We left this in place. Think of it as a scale swimming platform.

## Rudder Post

Getting the rudder post exactly right used to be an adventure, but I’ve changed my ways.  Put the keel fin in place.  Don’t force it in!  Rather sand it until it slides in easily but snuggly.  Now insert the rudder into the lower deck hole, position it both carefully fore and aft and starboard port and mark where the rudder shaft contacts cockpit.  Drill the hole for the rudder tube, insert the tube, and check if it’s perfect.  It will be about half of the time.  If it’s not, simply enlarge the top hole to about 10 mm.  Take a 15 mm square piece of 0.3mmm CF plate or an old credit card, and drill the hole for the rudder tube.  Position it exactly perfect, and glue in the plate with Stabilit.  When dry then glue in the rudder tube, also with Stabilit.  I got the v1 perfect the first time, and I needed the plate for the v2.

## Sand & Paint

Now wet sand the hull with 400 grit, then 600 grit paper.  If you’re like me, you’ll have a couple of glue drips.  Carefully wet sand these away with 220 first, but be very cautious to not take too much hull with the glue.  Getting the hull and fins very smooth is really important.  RC-sailboats, because of their small sizes and lower speeds, keep laminar flow much longerthan full sized boat.

Now paint the boat with spray enamel and allow to dry for maybe a week.  Then wet sand again with 400 and 600 grit paper, even 1200 or 1500 grit if you’re interested.

## On to the keel fin and bulb and rudders

There’s not much to it, except that you need to work precisely.  Most of the fastest boats use mark 1 fins and mark 2 bulbs.  (Mark 1 refers to a now extinct version of MM and mark 2 is the same as a current v1.) You’ve got a mark 2 bulb already, but you’ll need to order the mark 1 fin.  Currently Graupner USA does not (yet) carry these, so you’ll need to order one from Europe.  Whether you plan to use a mark 1 or 2 fin, it is a good idea to use a mark 1 rudder.

First, weigh the keel fin and bulb together.  You’ll want to be less than 415 grams.  The maximum is 420 grams and you’ll add a little weight in construction.  Now, measure the distance from the front tip

of the bulb to the front edge of the fin.  Shoot for 26 mm.  It has to be more than 25 mm.  If you need to lengthen the slot in the bulb, this is easily done by drilling into the area you need to remove with a drill the same diameter as the slot.  Then extend the slot using an xacto knife.  Now, check that the maximum depth is correct.  Shoot for 134 mm, the maximum being 135 mm (measured from where the fin exits the keelbox to the bottom of the bulb. If the bulb slot is all shiny and flat, roughen it a little with a file or some coarse sandpaper. If you need more depth, insert a toothpick into the slot below the fin.  If yo

u are using a mark 1 fin in a v2, note that the v2’s keelbox is slightly shorter than the v1.  You’ll need to trim a couple of millimeters off the top with an xacto knife and sand a little off of the aft edge of the keel insertion.  You can use your own mark 2 fin as a guide for this.

(Not Available) File:  DSC00628.jpg Caption: “Jack’s keel and rudder. Developmental work, but very pretty!”

Using a small hammer tap out any larger irregularities in the surface of the bulb.  No need for perfection.  Do not sand the lead bulb itself.  Draw a line carefully from the forward to the aft bulb tip on the side of the bulb.  You need a true perpendicular on the keel fin.  This is not so simple.  Watch a Micro Magic go up wind.  It is actually slightly bow down.

Here’s how to get a perpendicular: Put a mark just above the round area at the bottom of the bow (see picture).  Put the boat with the keel fin in place in the stand and carefully reposition the boat until the distance between the mark and the table and the bottom of the center of the transom and the table are exactly the same.  Now draw a perpendicular on the fin using a right angle. Remove the fin. Put it into the slot on the bulb and measure the angle between the two lines with a protractor.  Even though the two lines are not exactly in the same plane, it is easily possible to measure the angle within a degree or so.  According to a previous Model Yachting Theory and Practice article, you are shooting for 87-90 degrees, but absolutely not less than 87 or greater than 90.  Cocked way up or down is slow.

If your total keel weight (see above) was less than 410 grams and you extended the slot in the bulb to move the fin forward, buy some lead split shot as is used in fly fishing at your local fishing store and tack glue this in place in the excess slot with some thin CA glue.  The last step is easy:  glue the bulb to the fin with a little bit of Stabilit.  No need for a jig, just hold the bulb to the fin at an 87 – 88 degree angle with your hands until the glue sets up (about 10 minutes).  This sounds hard, but it’s as easy as can be.  Next, fill the slot with Stabilit up to the top of the slot and allow to dry.  Get some cheap, clear epoxy at the hardware store along with the cheapest little brush that you can find.   Paint the bulb with the epoxy, including the bulb – fin junction and put the keel fin in a vice with the aft bulb tip pointed down.  The excess will drip off of the bulb tip leaving you with a very smooth bulb with a sharp tip at the aft end.  Let dry for a couple of days.  Then wet sand the bulb with 220 grit until it is totally smooth and even.  While you are at it, round the forward edge of the fin and the rudder a little.  Both are way too sharp as they come in the kit.  Fill any irregularities with modeler’s putty.  Sand with 220 grit and very lightly spray with whatever color you plan on painting the keel.  I suggest a very light color so that you can see attached weeds from a distance.  The paint allows you to see irregularities better.  Repeat the sanding and filling until all is perfect.  I always plan on two iterations, but usually need three or four.  Lastly, wet sand the keel and rudder with 400 grit, apply the finish coats, and after 3-4 days, wet sand with 400, 600, and if you want 1500 grit.

## Servo Install

Install the servos.  Not much new or fancy here. Obviously, bolt the sail servo onto the mounting plate and screw the plate onto the keelbox with wood screws.  Screw in the rudder servo with wood screws.  Otherwise, you’ll have future trouble replacing them.  No need to mount the sail servo arm yet.  Jack and Ralf both mount their receivers on the starboard forward area of the sail servo mounting plate.  I mount mine on the port underside of the deck immediately adjacent to the keelbox.  Likely not much difference here functionally, both methods seem markedly preferable to the usual method of sealing it in a pill bottle or plastic bag and then velcroing to the side of the boat.  You’ll note that I used positive arms for rudder control.  I had felt for a long time that the standard pull-pull system on stock v1s was actually preferable, being lighter and more gentle on the rudder servo.  Jack agrees with this, as you’ll see i

n the pictures.  But Ralf’s single arm method is really slick, and I used it in both boats.  The main point is that the Z-spring makes it obvious when the rudder is hanging up, and you can look into it easily and promptly (even easier than the standard pull-pull system).  Also, Mike Eades had reported frozen junctions on single arm systems blowing rudder servos.  If you look carefully, I devised a simple no-freeze system.  When you mount the rudder, check it out carefully with the transmitter and sail servo to assure that you’re getting unimpeded movement through the entire range of motion.  This is really easy to see if you watch the rudder and the Z-spring together.

(Not Available) File: IMG_3276.jpg Caption: “Ralf’s boat doesn’t use a standard rear brace. Note the ABS rear strut braces instead. I did the same thing on the v1 and v2 except with 4mm CF tubing.

I was going to build one boat with an angled sail servo arm (in order to preferentially ease the main before the jib), but I ditched that when Dutch champion Elmer Boon scolded me to keep it simple, stupid.  (See the great interview with Elmer elsewhere in this issue.)  So, we’re running dead stock with the sail servo arms.  You can get a little of the “let the main out first” geometry just by bringing the jib sheet block in a screw hole or two.  That’s a marginal change, though.

## To the rig

Since you have already joined the AMYA and sent in your boat registration to me, now is a good time to put the numbers on your sails.

## Build the Mast

Then build your mast:  Jack (Mr. Reynold’s Number) uses nothing but 5 mm masts.  I have used both stock v1 five mm masts and Skyshark 2Ps (slightly more than 6 mm diameter).  The v2 comes with a 6 mm mast with 4 mm extensions on each end.  It was a good bit heavier than either the stock mark 1 or Skyshark masts, so I did not use it.  I put a stock v1 five mm mast into the mark 2.  I use tiny 1mm cotter-pins instead of the stock plastic piece for the jib-stay attachment and 2 pieces of 1mm CF rod for the mast crane.  Jack modifies the stock plastic pieces to the point of unrecognizability.  See the photos.  Don’t cut the bottom of the mast for length yet, but do fashion a 6mm diameter shim for the bottom of the mast using either the stock aluminum tube that comes with the v1 or an old left-over piece of 6 mm mast.  This should be cut to extend a mm or so above the top of the gooseneck.

(No photo) File: DSC00633.jpg Caption: “Jack’s gooseneck, strictly developmental, but very cool”

## Goosenecks and Vangs

Jack built a work of art of more than questionable legality, but a work of art nonetheless.  Actually, his boat is very much a developmental boat, he really isn’t very much concerned with legality.  If you see him at a regional regatta, you will likely note that he’ll be racing the v1 boat that we’re building here, not his developmental boat pictured here.  In the picture, you’ll note a stock VAM ball bearing gooseneck, an example of the typical Azura ball bearing goosenecks, and our best try of mocking up the gooseneck described by Elmer Boon in his article.  Pick which you like best.  The Azura design is from one of our ancient Keith Molen/Punta Gorda boats. The Azura gooseneck is made of a 20 by 52 mm piece of 0.40 mm (0.016”) aluminum plate bent around two sealed 6mm internal diameter bearings and glued with epoxy.  Don’t forget the little cotter pin.  This is used for the downhaul which leads to a piece of surgical tubing on the main boom.  The boom a la Boon is a chopped-up stock gooseneck and glued to a piece of credit card or 0.3 mm CF plate.  The idea here is that the boom stays in place for multiple rigs.  Note the little hook on the downhaul for quick rig changes.  Note that if you have the downhaul coming through the fixed piece of the gooseneck, you will need to trim it to the deck and if it goes on the boom side of the turning axis, it will need to be trimmed on the main boom.

## Booms

I have always used 4mm job and main booms.  Jack’s boat has them, too.  VAM booms are made of Skyshark 2P.  Elmer thinks that larger booms function as endplates.  I am skeptical about this claim (not

that endplates aren’t a good idea), but willing to give this a try, hence the 6mm main and jib booms on the v2 boat.  In my endeavor never to use any stock Graupner parts, I fashioned the main boom to gooseneck junctions from left-over servo arms.  This works great and is easy.  Ralf use stock jib boom counterweights, predictably, Jack uses a markedly modified one.  I use custom ones made from 4mm brass rod.  These look cool and are very quickly made with a dremel with a cutting disk and a drill press.  For a 4 mm boom use a 32 mm piece of rod, and turn down a 10 mm piece at the end to 3 mm to insert into the boom.  For a 6 mm boom, make a 10 mm shim out of some 5 mm CF tube and simply insert a 32 mm piece of 4 mm brass rod into it.

## Rigging

I use 20 lb. Spiderwire for everything except the jib boom to deck eye loop which is 80 lb. Spiderwire.  Jack uses 20 lb. Spiderwire for some stuff and 5 lb. for the rest. (Note that this is not a typo.)  Ralf fainted when he read that last sentence and hasn’t been heard from since.  I hope that he is recovering well.  I use 3mm internal diameter silicone tubing for 4 mm boom sliders, and 5mm silicone tubing for 6 mm boom sliders.  Both Jack and Ralf use many more Graupner connectors, in Jack’s case always highly modified.  Ralf likes little metal hook sliders made of piano wire for the tacks and clews.  I tie mine out of Spiderwire hoping for more flexibility.  I avoid bowsies like the plague in the wind stream, and when use the tiny stainless steel ones.  I use 1 mm CF rod for my forestays.  Ralf uses a more standard luff wire.

(No photo) DSC00669.jpg Caption: “Jack’s extremely developmental, but also extremely interesting rig.”

Lastly, note that both Jack and Ralf use trick outside adjusters for both the main and jib sheet.  I use a simple internal bowsie on the jib sheet only.  I adjust the main and jib together with the transmitter trim adjustment, and use the internal bowsie only to adjust the slot.

## Sails

The stock v1 sails are fast, so I used them.  The newer v2 sails are much improved from the original v2 sails, but the material is still quite heavy, so I used sailmaker sails on the v2.  The simplest way to get the proper mast height is to tape the head of your mainsail ¼” below the bottom of the masthead crane and cut the mast such that you get about 1/8” of downhaul adjustment.

## Batteries

There are 3 good choices.  You can use NiMh AAA 4 or 5 cell battery packs.  These are ~700 mAh.  The 4 cell pack weighs 51 grams, the 5 cell packs 64 grams.  HobbyKing makes a really nice 700 mAh LiFe battery. It is 2 cell (2s) and weighs 55 grams.  Since it has 2 cells, it requires balance charging, but this is not really a big deal after you get used to it. It is 6.6 volts.  This is not too much for the servos.  Lastly, if you have a boat which is over the 860 gram minimum weight, consider cell phone batteries from HobbyKing.  These are single cell LiPOs, implying 3.7 volts and no balance charging.  The 3.7 volts works fine with most receivers.  They are 600 – 750 mAh, and almost magically they weigh only 15 – 20 grams.  You do have to solder the connector wires on yourself and you have to know how to figure out which is the positive pole. (Both tasks are easy.)  We use them routinely at Azura.  We package them in little ziplocks and tape watertight with strapping tape. They do have the disadvantage that some of them swell with gas after 18 – 24 months.  When this happens, they should no longer be used and they should be disposed of properly.

File: DSC00674.jpg Caption: 3 options for batteries.  Note that some skippers also use 5 cell NiMh AAA packs.

(Not Available) File: DSC00686.jpg Caption: “Pumpkin is the v2.  Just by chance, she weighs 860 grams on the head.”

All three of us wish you fun with your building and even more fun sailing your new Micro Magic! We really had a good time with this project, and we recommend it to all of you.  The boats are fun to build and come out just great!

### Suppliers:

• Servos – ServoCity, Graupner USA
• Carbon Fiber Plate and Rod – HobbyKing, Midwest Carbon Fiber, Goodwinds Kites
• Rudder Fasteners – Tower City
• Rudder Fasteners – Tower City
• Ball Bearings – Fast Eddy Bearings
• Aluminum Sheet – Most hobby shops
• Goosenecks – VAM
• Silicone Tubing – Aquarium shops, Amazon
• Piano Wire – Most hobby shops
• Keel Fins and Rudders – Graupner.de, RC-Zeilen.nl
• Goosenecks – VAM
• European Glues – RC-Zeilen.nl, Conrad.de
• Sails – Black Magick, Carr, Cat, Ken Bauser, VAM, Sirius