SailingStop Dictionary of Sailing Terminology

An Informal Dictionary of Sailing Terminology put Together by Real Sailors

Anchor
A device used to prevent or slow the motion of a boat. It is deployed off the boat (usually from the bow or stern) and attached to the boat with a line. Usually an anchor is in reference to a metal wedge type device that is designed to dig into the sea floor and then hold a boat in place. There are many different anchor designs that are relatively effective. Choosing the right anchor depends on many factors including the material it will be digging into, and whether the anchor is tethered to the boat with a chain or line, or combination of line and chain.

The term "anchor" can also be in reference to a sea anchor, which is essentially a small parachute that is deployed under water. A sea anchor is designed to slow a boat in heavy seas, and keep the boat pointed in a specific direction relative to wave action.

Anchor Light
An anchor light is a white light that sits at the very top of a mast. It should only be illuminated when a boat is actually anchored, and serves as a warning to other boats. When a boat is tied up to a mooring, dock, or other semi-permanant structure, it is not necessary to use an anchor light.

Backstay
A backstay is the stay that runs from the top of the mast to the stern of the boat. Like other stays, it is a strong wire, rod, or line that is used to prevent the mast from being blown over. The backstay is specifically designed to prevent the mast from blowing forward. Backstays sometimes have adjustable tension in order to shape the mast (and consequently the sail) in varying wind conditions.

Block
A block is essentially a pulley that is used to either guide a line, or develop "purchase" on a line. "Purchase" is in reference to the ability to decrease the force necessary to pull on a line through the effective use of pulleys.

Boom
A boom is a horizontal spar that is generally attached to the mast at one end, and attached to the aft corner of a sail (the clew) at the other end. The boom is used to hold the sail out in a horizontal direction.

Bow
The bow is a nautical term used to describe the front of the boat. It is a noun.

Bowsprit
The bowsprit is a spar that extends forward of the hull of a boat. It can be used for a variety of things, including a more forward point to attach a forestay and/or a sail such as a spinnaker or jib.

Cabin
The cabin of a boat is essentially the interior living space of a boat. This is always in reference to permantly enclosed quarters, as opposed to a temporary superstructure above the deck.

Captain
The captain is responsible for everything aboard a vessel. The captain's opinion is the ultimate authority when it comes to all decision making aboard a boat. If a crew refuses to follow a captain's orders, it is considered mutiny.

Centerboard
A centerboard is a substantially flat fin that is extended below a boat (underwater). It runs on the centerline and is designed to prevent a boat from going sideways when the wind fills the sails. The centerboard makes it easier for the boat to move forward than sideways. Centerboards are always retractable devices (if it is fixed then it is called a keel) and they can be either weighted, or unweighted. Weighted centerboards serve to help stabilize a boat from rolling over.

Cleat
A cleat is a piece of hardware designed to hold a line. In the most traditional sense, a cleat is a piece of metal or wood that is shaped somewhat like an anvil. A special knot known also as a cleat is used to tie a line to these traditional cleats.

Newer type of cleats such as jam cleats do not require a knot to be tied. Jam cleats allow a line to move in one direction only. This allows someone to pull the line in, but prevents it from going back out when the person lets go of the line. The line can subsequently be popped out of the jam cleat to let it out.

Clew
The term "clew" is very specifically used to reference the aft corner of a sail. The is one of the corners of the sail that attaches to the boom.

Companionway
The companionway is the entrace to the cabin of a boat. Typically there is a form of ladder or steep steps that leads from the companionway opening on deck down into the cabin of a sailboat.

Crew
The crew of a boat generally is a reference to all of the people involved in the working of a boat except for the captain. It also would not include any passengers.

Deck
The deck of a boat is the horizontal outside surface that one walks upon. When you are outside on a boat, the deck is your floor. When you are in the cabin of a sailboat the deck is usually the ceiling above you.

Dress Ship
Dressing Ship is a customary way to decorate the outside of a boat for special occasions. It very narrowly refers to the hoisting of a string of signal flags that runs from the bow of a boat, to the top of the mast, and then back down to the stern of the boat.

Deck Prism
A Deck Prism is a prism of glass that is used to bring light into the cabin of a boat. It is installed flush with the deck, runs through a hole in the deck, and has a prism below deck to spread light. These were used fairly regularly in the past, but are uncommon on modern boats.

Ensign
An Ensign is a flag flown from the stern of a ship that identifies the nationality of a vessel. In the case of the United States, it can either be a traditional american flag, or a nautical version of the U.S. flag.

Foot
The foot of a sail is a reference to the bottom edge of a sail. The forward corner of the foot is the tack, and the aft corner of the foot is the clew.

Forestay
The stay that runs from the top of a mast to the bow of the boat. As with other stays, a forestay is made from strong wire, rod, or line, and is used to prevent the mast from being blown over. On some sailboats the forestay attaches to the mast slightly below the very top. If this is the case, the sailboat is considered to have a "fractional rig". A forestay can also be called a headstay.

Fractional Rig
A sailboat whose forestay attaches to the mast below the top of the mast. If the forestay does go to the top of a mast it is called a "masthead rig".

Furl
To take a sail, or sails, down. Furling can be done by simply lowering a sail, or by rolling it using a furling device.

Genoa
A large sail that is flown forward of a mast. Generally the leech of the sail (aft edge of the sail) must be further aft than the mast in order to be considered a genoa. The the forward sail is smaller and the furthest aft it comes is the mast, then it is considered a jib. A genoa is often referred to as a "jenny".

Halyard
Any line that is used to haul things up and down a mast. Its most common function is to raise and lower sails. In this case, the name of the sail preceeds the term "halyard" in order to differentiate between lines. For example: the "main halyard" is the line dedicated to hoisting the main sail.

Hatch
An opening in the deck of a boat that can be tightly closed or sealed if necessary in order to prevent water from entering the cabin. Hatches provide ventilation when open, and are often clear so as to allow light into the cabin whether they are closed or open.

Head
"Head" has two very specific definitions on a boat.

The first definition: the bathroom on a boat. A common way of declaring your intention to use the bathroom on a boat is to say, "I'm going to hit the head." It can refer both to the room in which the bathroom is housed, as well as the toilet itself.

Definition two: the top corner of a sail.

Hull
The main structural outer skin of a boat. Most modern boats have fiberglass hulls.

Hull Port
A window in the hull of a boat. This differs from the bulk of a sailboats windows that are typically cut into the deck or cabin top. Hull ports frequently do not open for safety reasons, whereas the ports on deck usually do open.

Jenny
The informal name for a "genoa". Please see Genoa.

Jib
The sail that goes forward of a mast. The leech of a jib generally does not go any further aft than the position of the mast. If it is larger than that, it is considered a genoa.

Jib Sheet
The line used to control how far out the jib goes. The jib sheet attaches to the clew of the jib and generally goes back to the cockpit of a boat for more convienant control by the crew.

Keel
The part of a boat's hull that extends below the waterline, on the boats centerline, that is used to counterbalance the tendency of wind to blow a sailboat over. A keel generally is shaped something like a fin, so as to cut through the water and prevent sideways motion of the boat. It also will always have weight at its lowest point to prevent the sailboat from tipping over.

Ketch
A reference to the way in which a boat is rigged. A ketch has two masts with the aft mast being shorter than the forward mast (or main mast). The aft mast must be forward of the rudder post.

Knot
Slang for "nautical mile per hour", the standard measuring unit for speed on a boat. One Knot is equal to 1.15 miles per hour. Both boat speed and wind speed are measured in knots.

Knot may of course also refer to the way of manipulating a line to in order to attach it to something.

Leech
The aft edge of a sail. The leech runs from the head of the sail (at the top of the mast) to the clew of the sail (at the end of the boom).

Leward
A reference to the downwind side of a thing. Often the term leward is used to describe the position of something relative to a boat.

Luff
The forward edge of a sail. The luff runs between the head of a sail (at the top of a mast), to the tack of a sail (at the lower forward corner of a sail).

Luffing
A term used to describe the flapping of a sail in the wind. Luffing generally occurs if a sail is too far out relative to the wind. If a sail is too far out, it will wave like a flag and is said to be "luffing". Luffing your sails will slow your sailboats speed as it increases drag and decreases the performance of the sails. If a sail is trimmed properly, it will not flutter at all.

Main Sail
The sail that is located aft of the mast on a sloop.

Main Sheet
The line that is used to control how far out the main sail goes. The main sheet attaches to the end of the boom, at the clew, and comes back to the cockpit for control by the crew.

Mast
The vertical spars on boats. A mast is supported by stays so that it does not blow over from the force of the sails. The purpose of the mast is to provide the basic support for the system of sails. Masts were originally made of wood, then aluminum, and now they are sometimes made of carbon fiber. The weight of a mast is extremely important because it cancels out weight in the keel.

Mast Step
The support for the bottom of the mast. The mast step can either be located on the deck of a sailboat (in which case the deck must be well supported at that point), or at base of the hull inside the cabin. Many sailors place a coin under the mast at the mast step for good luck.

Mizzen
The smaller sail, supported by its own mast, aft of the main mast on a ketch or yawl.

Mizzen Mast
The smaller mast, aft of the main mast, on a ketch or yawl.

Outhaul
The line that pulls the clew of the mainsail out to the end of the boom. The outhaul is generally a control line that is used to help control the flatness of the mainsail.

Painter
The bow line on a dinghy. The painter is what is used to tow a dinghy behind a sailboat. It is also used to tie a dinghy up.

Port
The term "Port" has two definitions on a boat.

Definition One: the left side of something, or the direction "left".

Definition Two: A window either in the cabin top, or the hull.

Rig
All of the superstructure on a sailboat used to support the sails. The rig mainly includes the mast, spreaders, and stays.

Roller Furler
A device used to roll up a sail for storage. Roller furlers are generally controlled by a line, or a motor. A roller furler is a more convienant way to furl a sail when compared to traditional furling. Primarily used for jibs, a roller furler allows a sail to remain up (the halyard is not lowered), but still be rolled tightly enough so as to prevent the sail from catching any significant wind. Roller furlers can also be installed in masts or booms to allow for roller furling of a mainsail.

Schooner
A reference to the configuration of the sails on a sailboat. A schooner must either have 3 or more masts, or have two masts with the aft mast being the tallest. Schooners were the dominant rig for larger boats in the days of working sailboats.

Sheet
The main control line for sails. Sheets always attach at the clew of a sail and control how far out a sail can go with respect to the centerline of the boat. Specific sheets are identified by adding the sail they control to the beginning of the word. For example, the "mainsheet" controls the mainsail.

Shroud
The sidestays that prevent sideways motion of the mast relative to the boat. Often multiple sets of shrouds will be used on each side of the mast. The shrouds will each go to different heights on the mast, as opposed to only going to the top of the mast. This is to prevent bowing of the mast under load from the sails.

Sloop
A sailboat with only one mast.

Spar
Any rigid pole used to help support the sails on a sailboat. Typical spars include: masts, booms, spinnaker poles, and bowsprits.

Spinnaker
A large sail flown from the bow of a boat that is only connected to the boat at the sails three corners (the clew, tack, and head). Spinnakers are generally used for downwide sailing, and can be difficult to control. Normal spinnakers require a spinnaker poll that attaches to the mast and goes out to the clew of the sail in order to open up the sail to catch as much wind as possible. Asymetrical spinnakers on the other hand have a different a shape and do not require a spinnaker pole.

Spreader
Horizontal structural supports for a mast. Spreaders interact between shrouds and a mast to help provide support for the mast.

Sprit
Short for "bowsprit".

Stanchion
The vertical supports for the "railing" around the edge of a boat.

Starboard
The right side of something, or the direction "right".

Stay
A wire, rod, or line used to hold a mast in place. In general a sailboat has a forestay (coming from the bow to the masthead), sidestays (coming from the side of the boat), and a backstay (coming from the stern of the boat to the masthead).

Stern
The back of a boat.

Tack
There are two definitions for the term "tack" on a sailboat.

Definition One: The lower forward corner of a sail.

Definition Two: Verb meaning to turn the boat in such a manner that the wind crosses the bow of the boat. Sails are adjusted accordingly when a boat tacks.

Traveler
A piece of hardware that generally runs on a track allowing for the adjustment of where the mainsheet comes back to the cockpit.

Vang
A device that controls the angle between the mast and the boom. Vang's are usually made from pulleys and line or they are hydraulic. The ultimate goal is to help shape the mainsail.

Winch
A drum type device used to pull lines in when a significant amount of force is on the line. Winches allow the operator to use mechanical advantage to bring in a sail.

Windless
A type of winch used to pull an anchor line up. The windless is always located on the bow of the boat.

Windward
A reference to the upwind side of a thing. Often the term windward is used to describe the position of something relative to a boat.

Yawl
A reference to the way in which a boat is rigged. A yawl has two masts with the aft mast being shorter than the forward mast (or main mast). The aft mast must be aft of the rudder post.