SailingStop Dictionary of Sailing Terminology
An Informal Dictionary of Sailing Terminology put Together
by Real Sailors
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.
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.
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.
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.
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.
The bow is a nautical term used to describe the front of the
boat. It is a noun.
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.
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
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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".
To take a sail, or sails, down. Furling can be done by simply
lowering a sail, or by rolling it using a furling device.
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".
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.
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.
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.
The main structural outer skin of a boat. Most modern boats
have fiberglass hulls.
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.
The informal name for a "genoa". Please see Genoa.
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.
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
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
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
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.
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).
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.
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).
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.
The sail that is located aft of the mast on a sloop.
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.
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.
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.
The smaller sail, supported by its own mast, aft of the main
mast on a ketch or yawl.
The smaller mast, aft of the main mast, on a ketch or yawl.
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.
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
The term "Port"
has two definitions on a boat.
Definition One: the left side of something, or the direction
Definition Two: A window either in the cabin top, or the
All of the superstructure on a sailboat used to support the
sails. The rig mainly includes the mast, spreaders, and stays.
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.
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.
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 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.
A sailboat with only one mast.
Any rigid pole used to help support the sails on a sailboat.
Typical spars include: masts, booms, spinnaker poles, and
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
Horizontal structural supports for a mast. Spreaders interact
between shrouds and a mast to help provide support for the
Short for "bowsprit".
The vertical supports for the "railing" around the
edge of a boat.
The right side of something, or the direction "right".
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).
The back of a boat.
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.
A piece of hardware that generally runs on a track allowing
for the adjustment of where the mainsheet comes back to the
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.
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.
A type of winch used to pull an anchor line up. The windless
is always located on the bow of the boat.
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.
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