Sailing Basics – Terminology

Sailing Terminology

This post defines the many terms used in sail boating. It is limited to terms relevant to model yachts. It contains terms about parts of a sailboat, functions of items on a sailboat, sailboat terms, and the parts of sails.

Like many sports or professions sailing has its own terminology. Developed over the last several hundred years with all the richness that comes along with that. At first glance many of our sailing terms may seem to have been assigned in a haphazard manner but, they have all developed out of nautical traditions, mostly from Europe.

For instance, the terms for right and left come from a time when ships used a steering board slung over one side of the boat. With sheer man-power or block and tackle they would apply leverage to the steering board to make their turns. Imagine coming into port and docking; you wouldn’t want to dock on the side the steering board is on so the other side of the boat, facing the port, came to be called ‘port’ and the side of the boat the steering board was on became known as ‘starboard’.


Note: Most of the content of this post is from the “School of Sailing” website. You can use the link to pursue building your sailing knowledge at that site.

This post has been edited to remove all, at least most, of the information that is not relevant to our models.

The entries below are copied from the Glossary.

Parts of a sailboat

A stay (line) that runs from near or at the top of the mast to the stern of the boat.
A spar that supports the foot of the mainsail. See figure #1.
The forward part of a boat also called ‘the pointy end’.
The fitting that attaches the boom to the mast.
Also called forestay, a cable /line that runs from the bow to the upper part of the mast. figure #5.
The underbody of a boat. See figure #5.
jib. A foresail (headsail) that fits inside the foretriangle. See figure #5.
keel. An extension of the hull that goes deeper into the water and provides stability from heel and sideways resistance to wind; as in: A well designed keel can provide lift to windward. See figure #5.
mainsail. The main sail of a boat, often the largest sail and raised on the
mainmast. See figures #1 and #5.
mast. A pole made from wood, aluminum, or carbon fiber on which a sail is set;. See figures #1 and #5.
shroud. A wire or cable holding up the mast athwartships (side to side)
spreader. A horizontal support for the stays that sticks out from the mast.
stern. The aftermost part of a vessel See figure #5.

Functions of Items on a Sailboat

topping lift. A line that runs from the end of the main boom to the mast in order to hold it up when the sail is not set.

boom vang. A device to hold the boom down; as in: Use the boom vang to
prevent the boom from rising up while on a run.
downhaul. Used to place tension in the luff of a sail.
halyard. A line attaches the sails to the mast.
jib sheet. A line that controls the jib.
mainsheet. A single line used to control the main.
outhaul. A sail control that attaches to the clew and allows tensioning of the foot of the sail.
rudder. An underwater appendage that controls the direction of the boat. See figure #5.

stay. A wire or cable supporting the mast, also see: “headstay” and “backstay”. See figure #5.

telltale. A fine string or ribbon which may be located on a sail or in the rigging to help determine wind direction and proper sail trim. See the Sail Trim post.

Sailboat terms

abeam. At a right angle to the boat.
astern. Behind the stern of the boat.
beam. The widest part of the boat.
draft. The depth of the boat underwater
heel. The angle the boat sails at.
jibe. To turn the stern of the boat through the eye of the wind. See Tacking and Jibing post.
lee and leeward (pronounced “lee” and “loo-ward”).
port. left side when looking toward the bow.
running rigging. All the lines that control any part of the sails including sheets, halyards, and outhaul.
standing rigging. All wires or cables that hold up the mast.
starboard. The right side facing the bow.
tack(ing). To change tacks by putting the bow through the eye of the wind.
weather helm. The tendency of a boat to turn into the wind.
windward. Towards the wind, upwind.

Sails and parts of a sail

Figure #5

Sailboat showing names of sails, hull, keel, rudder, bow, stern, forestay, backstay, battens, head, tack, clew, foot, luff, and leech.

batten. A strip used to stiffen the leech of a sail.
clew. The after lower corner of a sail.
foot. the bottom edge of a sail.
head. the top corner of a triangular sail.
jib. A foresail that fits inside the foretriangle of the mast and head stay.
leech. The back edge of a sail.
luff. the leading edge of a sail.
tack. To change tacks by putting the bow through the eye of the wind.

Sailing Basics – True and Apparent Wind


Note: Most of the content of this post is from the “School of Sailing” website. You can use the link to pursue building your sailing knowledge at that site.

True and Apparent Wind

There are two kinds of wind; true and apparent. We call the wind that blows across the land or water, the true wind. This is the wind talked about in the weather forecast of 10-15 knots for instance. It is the wind we feel when we are outside at rest and not moving.

As you might guess the other kind of wind, apparent, is the wind that is generated by our movement in combination with the true wind. The only time there is no apparent wind is when we are at rest and only feeling the effects of the true wind. When we move and the wind also moves the total wind we feel is the apparent wind. Stationary objects only feel true wind while all objects in motion feel apparent wind.

Let’s talk about some examples and start with the situation where there is no true wind. This is a day when it is completely calm with no detectable wind speed when we are standing still.


Boat with apparent wind only.

In this illustration we have calm conditions so we motor ahead at 5 knots producing an apparent wind of 5 knots from straight ahead.



On the next day, tied up at the dock, we have a true wind of 10 knots constant blowing across our port beam.

Boat with true wind only.

No wind from our boat’s forward motion. The true wind is 10 knots and that’s what we feel on the boat. What happens when we go sailing?


Lucky us! The wind will just blow us off the dock. We raise sails and move ahead on a close reach at 5 knots. We know the true wind is 10 knots and, since we will be moving forward we will be producing 5 knots of wind ourselves. How do these combine? We are combining our boat speed and direction with the true wind speed and direction.

boat with both true and apparent wind

We see the combined effects of the true wind and our boat’s motion forward. This produces the apparent wind, what we actually feel while sailing on the boat. Boats always sail in the apparent wind. Here, note the apparent wind is stronger than the true wind (the arrow is longer) and is coming from further towards the bow.

What if we fall off the wind and head down on a run? Let’s see what the combination of boat speed and direction along with the true wind produce now.

boat showing both true and apparent wind on a run.

As we turn away from the wind the boat slows down. It slows down because the apparent wind drops and the sails become less efficient. In this simple example we are going in the same direction as the wind so we just subtract our boat speed from the true wind speed and that gives us the correct apparent wind speed. If we have a wind speed indicator aboard it would show the same reading.

Sailing Basics – Tacking and Jibing


Note: Most of the content of this post is from the “School of Sailing” website. You can use the link to pursue building your sailing knowledge at that site.

Tacking and Jibing

If our destination or the direction of the wind change we will need to change our course. Many times this means changing the tack of the boat. If you refer back to Points of Sail you will see there are two tacks the boat can be on; starboard or port. Starboard tack boats carry their boom and mainsail on the port side while port tack boats do the opposite. When changes tacks we are moving the boom to the other side of the boat and usually move the head sail there also.


Tacking the boat is putting the bow through the eye of the wind. Sailboats can’t sail directly into the wind so if our destination lies upwind we will need to tack back and forth to get there. Let’s look at what a tack looks like.

Tacking a sailboat.

Some boat speed is required to insure we make it all the way through our tack. This is especially important for catamarans and slow, full keeled monohulls. If you do get stuck part way through it’s called ‘in irons’, just push the boom out and get the boat going backwards, if even a little. In short order you’ll be able to sail again. Tacking is a basic sailing skill, proficiency comes with a bit of practice.









Jibing is putting the stern of the boat through the eye of the wind. Here, we must be vigilSailboat jibing.ant about an accidental jibe. Unlike the tack above where the boom is moving slowly, when we jibe the boom is given to violent move and if we are not prepared damage can be done to boat equipment and any bodies that get in the way. Let’s take a close look at how this maneuver can be carried out.


Unlike tacking where we need boat speed to carry us through in jibing it is better to do it slowly until you’ve become very proficient. The boom coming across the boat is dangerous and must be done in a controlled manner.

Practice tacking and jibing often. A good way to do this is to practice lots of crew overboard recoveries. You can learn more by going to Crew Overboard.











Sailing Basics – Weather Helm and Lee Helm


Note: Most of the content of this post is from the “School of Sailing” website. You can use the link to pursue building your sailing knowledge at that site.

Weather Helm and Lee Helm

Balancing the boat between weather and lee helm creates the most efficient and effective way to sail any boat. Weather helm is the tendency of a boat to turn itself into the wind (weather). Lee helm is the tendency for a boat to turn itself away from the wind or downwind. Too much weather helm and she’s not only hard to steer but slower than if balanced. Too much lee helm and she wants to sail down wind. To understand how a sailboat balances we’ll take a look at a simple weather vane.

Weather vane illustrating effects of wind.

Weather vanes are designed to always point into the wind. They do this because the back vane is larger than the forward vane. Another important factor is where the axis of rotation is located. Here, it’s located in the middle. Since the vane in the back is larger the point at which the two vanes balance each other is behind the rotation point. Move the axis of rotation further and further back and sooner or later you’ll reach the balance point of the two vanes and the weather vane will no longer point into the wind. Instead, it will swing back and forth never really coming to a direction. Move the rotation point even further back, behind this balance point, and the weather vane will point down wind.


Illustration showing weather vane pointing downwind.

Here, the weather vane points downwind because its point of rotation has been moved to the very back. With the weather vane there are two variables at work: 1) The relative size of the two vanes and 2) the position of the axis of rotation. Sailboats work exactly the same way, let’s see how.





Sailboat showing centers of effort for sails.

The sailboat here shows the center of effort for the jib and the main and the combined total CE for the sail plan. On the keel is labeled the CLR or center of lateral resistance which is the turning axis for the boat. The CE is calculated for each sail by drawing three lines; one from each corner to the middle of the opposite side and where the lines intersect is the CE. Then, the CEs are combined to find the overall CE. The CLR is calculated by the designer but you could figure it out by pushing on the side of the boat at different places until you found the spot that, when pushed, would produce a perfect sideways movement.

To have a perfectly balanced sail plan it would seem that, as in the weather vane above, the CE and the CLR should line up. What actually happens is the sailboat will automatically, because of the shape of her hull, develop weather helm as she heels. The CE will then need to slightly ‘lead’ the CLR to create a boat with initial proper balance.

So what does all this mean? A boat that has proper balance between weather and lee helm will be easy to steer and will also make her way efficiently through the water. Imagine steering a boat with no detectable helm in other words she has a perfect balance; there would be no ‘feel’ to the steering wheel or tiller. For a couple of reasons it is good to have a slight amount (about 3°) of weather helm. This gives the needed ‘feel’ to wheel or tiller, the rudder works most efficiently, and, in the case of the helmsperson falling overboard, the boat would have a tendency to round up into the wind.

What’s wrong with too much weather helm? Think about this: how do you counteract the tendency for the boat to turn into the wind? What do you do when you want the boat to go in a certain direction? You turn the rudder. So, the more weather helm the more you need to turn the rudder. Not only is this quite tiring but it is slowing the boat down. When you drag a large appendage sideways through the water it takes a lot of force to make it move. This force could be going into driving the boat faster but you are now using it turning the rudder sideways slowing you down.

Properly balanced. How do you reduce weather helm to the correct amount? Too much weather means that the CE is too far aft, how can we bring the CE forward? If we made the main smaller by reefing it that would bring the CE forward. If we move the traveler to leeward that also brings the CE of the main forward thus bringing the combined CE forward. We could rake the mast forward by tightening the forestay and easing the backstay. We could induce mast bend by tightening the backstay.

You might not think we could adjust the CLR of the boat but, on smaller boats, it’s pretty easy to do. Too much weight in the bow creates weather helm by bringing the CLR forward. Move weight aft to decrease weather helm.

When you are making adjustments try to keep in mind where the CE and CLR are and how you want to adjust their relationship.

What might we use lee helm for? We know lee helm means the boat will naturally want to sail itself downwind. How about if our destination lies downwind and we’ll be traveling on a run or close to it? We might very well choose to be lazy and just use a large sail forward such as a cruising spinnaker. Maybe not quite so fast as if we also used the main but the boat will be easy to control and sail with no possibility of an accidental jibe.

Sailing Basics – Sail Trim


Note: Most of the content of this post is from the “School of Sailing” website. You can use the link to pursue building your sailing knowledge at that site.

Sail Trim

Air should flow smoothly across both sides of the sails. Ideally, you would only notice a bit of disturbance in the forward part of the mainsail because the air there is in the shadow of the mast. The sails will look as if they were rigid, with no puffiness or flopping. We call this flopping of a sail luffing because it starts at the luff (leading edge of a sail) and works its way aft. Adjustments to sail shape are required to keep the boat in balance and sailing as efficiently as possible.

A more sensitive way to judge the correct trim is through the use of telltales. These are strings of yarn on each side of the luff of the head sail (forward sail) and on the leech of the mainsail.

Boat with telltales flying.

Here we see the telltales in blue are streaming back nicely. Think of the head sail and mainsail as one airfoil and trim accordingly. Head sail and main work together to increase their efficiency. The head sail increase the flow of air over the main; in effect funneling more air across it than would otherwise be the case.



Mainsail in section.

Left we are looking down on the main from directly above showing how air flows across the sail.



In light to moderate winds we focus on powering up the sails making them fuller with greater curve, or draft. In stronger winds, 15 knots or more apparent, we are making the sails less powerful by flattening them or reducing their size by reefing. Less powerful sails reduce heel and keep weather helm at an appropriate level.

Let’s start out on a beam reach and see what that looks like from above the boat. All the points of sail are covered in Points of Sail.

Sailboat on a beam reach

Even though we are on a beam reach (the apparent wind is coming directly over the beam of the boat) trimming the sails for a close reach, broad reach, and run is somewhat similar. We ease the sails out until the telltales flop around (stall) then trim in the sails just until the telltales stream straight back. We aim the boat where we want it to go and adjust the sails accordingly. On a broad reach or run we may choose to use the boom vang to hold the boom down. Otherwise the vang is kept loose.

If our destination lies straight upwind then we will need to go as close to the wind as possible. This point of sail is called close hauled or beating. Here, we set the sails to their close hauled position and adjust the course of the boat to achieve our goal of streaming the telltales straight back. By making small adjustments the sails will fill with air and become full or, by steering more towards the wind, they will start to luff and lose power.

Sailboat sailing close hauled

We are trying to sail as close to the source of the wind as possible because we want to go somewhere that lies upwind of our present position. Here, trim in the main so the boom is close to the center line of the boat and trim the head sail in all the way. Then, make small course changes as you go upwind to keep the telltales streaming straight back. If weather helm becomes a problem then move the traveler to leeward. The mainsail is adjusted with both the main sheet and traveler. Using the traveler alone allows us to change the angle of attack of the sail without changing its shape. If there is still too much weather helm it may be time to reduce sail by reefing.

Sailing Basics – Points of Sail


Note: Most of the content of this post is from the “School of Sailing” website. You can use the link to pursue building your sailing knowledge at that site.

 Points of Sail

You will find the definitions of each of the points of sail following the diagram.












close hauled. A point of sail, sailing as close to the wind as possible, also known as beating; as in: Sailing close hauled can be challenging.

close reach. A point sail between close hauled and a beam reach; as in: Returning to the crew overboard, she sailed the boat on a close reach.

beam reach. Point of sail with wind coming over the beam; as in: Fall off to abeam reach from a close reach.

broad reach. Point of sail with the wind coming over the boat’s quarter; as in: Falloff from a beam reach to a broad reach.

running. A point of sail; as in: Falling off from a broad reach we will be running.

port. 1, left side when looking forward.
port tack. A sailboat is on port tack when the mainsail is on the starboard side (the wind will usually, but not always, be on her port side); as in: When we’re on a port tack we must give way to starboard tack vessels.

points of sail. Close hauled (beating), close reach, beam reach, broad reach, and run; as in: Sailing a full circle we will cover all the points of sail. See illustration below: