- ABAFT -
- Toward the rear (stern) of the boat. Behind.
- ABEAM -
- At right angles to the keel of the boat, but not on the boat.
- ABOARD -
- On or within the boat.
- ABOVE DECK -
- On the deck (not over it - see ALOFT).
- AFT -
- Toward the stern of the boat.
- AGROUND -
- Touching or fast to the bottom.
- AHEAD -
- In a forward direction.
- AIDS TO NAVIGATION (AtoN) -
- Artificial objects to supplement natural landmarks to indicate
safe and unsafe waters.
- ALOFT -
- Above the deck of the boat.
- AMIDSHIPS -
- In or toward the center of the boat.
- ANCHOR -
- A heavy metal device, fastened to a chain or line, to hold a
vessel in position, partly because of its weight, but chiefly
because the designed shape digs into the bottom.
- ANCHORAGE -
- A place suitable for anchoring in relation to the wind, seas and
- ASTERN -
- In back of the boat, opposite of ahead.
- ATHWARTSHIPS -
- At right angles to the centerline of the boat; rowboat seats are
- BATTEN DOWN -
- Secure hatches and loose objects both within the hull and on deck.
- BEACON -
- A lighted or unlighted fixed aid to navigation attached directly
to the earth's surface. (Lights and daybeacons both constitute
- BEAM -
- The greatest width of the boat.
- BEARING -
- The direction of an object expressed either as a true bearing as
shown on the chart, or as a bearing relative to the heading of the
- BELOW -
- Beneath the deck.
- BIGHT -
- The part of the rope or line, between the end and the standing
part, on which a knot is formed. A shallow bay.
- BILGE -
- The interior of the hull below the floor boards.
- BITTER END -
- The last part of a rope or chain. The inboard end of the anchor
- BLOCK -
- A wooden or metal case enclosing one or more pulleys and having a
hook, eye, or strap by which it may be attached.
- BOAT -
- A fairly indefinite term. A waterborne vehicle smaller than a
ship. One definition is a small craft carried aboard a ship.
- BOAT HOOK -
- A short shaft with a fitting at one end shaped to facilitate use
in putting a line over a piling, recovering an object dropped
overboard, or in pushing or fending off.
- BOW -
- The forward part of a boat.
- BOW LINE -
- A docking line leading from the bow.
- BOW SPRING LINE -
- A bow pivot line used in docking and undocking, or to prevent the
boat from moving forward or astern while made fast to a pier.
- BOWLINE KNOT -
- A knot used to form a temporary loop in the end of a line.
- BOWSPRIT -
- A spar extending forward from the bow.
- BRIDGE -
- The location from which a vessel is steered and its speed
controlled. "Control Station" is really a more appropriate
term for small craft.
- BULKHEAD -
- A vertical partition separating compartments.
- BUOY -
- An anchored float used for marking a position on the water or a
hazard or a shoal and for mooring.
- CABIN -
- A compartment for passengers or crew.
- CAPSIZE -
- To turn over.
- CAST OFF -
- To let go.
- CATAMARAN -
- A twin-hulled boat, with hulls side-by-side.
- CHAFING GEAR -
- Tubing or cloth wrapping used to protect a line from chafing on a
- CHANNEL -
- 1. That part of a body of water deep enough for navigation through
an area otherwise not suitable. It is usually marked by a single or
double line of buoys and sometimes by range markers.
- 2. The deepest part of a stream, bay, or strait, through which the
main current flows.
- 3. A name given to a large strait, for example, the English
- CHART -
- A map for use by navigators.
- CHINE -
- The intersection of the bottom and sides of a flat or v-bottomed
- CHOCK -
- A fitting through which anchor or mooring lines are led. Usually
U-shaped to reduce chafe.
- CLEAT -
- A fitting to which lines are made fast. The classic cleat to which
lines are belayed is approximately anvil-shaped.
- CLOVE HITCH -
- A knot for temporarily fastening a line to a spar or piling.
- COAMING -
- A vertical piece around the edge of a cockpit, hatch, etc. to
prevent water on deck from running below.
- COCKPIT -
- An opening in the deck from which the boat is handled.
- COIL -
- To lay a line down in circular turns.
- COMPASS -
- Navigation instrument, either magnetic (showing magnetic north) or
gyro (showing true north).
- COMPASS CARD -
- Part of a compass, the card is graduated in degrees, to conform
with the magnetic meridian-referenced direction system inscribed
with direction which remains constant; the vessel turns, not the
- COMPASS ROSE -
- The resulting figure when the complete 360° directional system is
developed as a circle with each degree graduated upon it, and with
the 000° indicated as True North. Also called true rose. This is
printed on nautical charts for determining direction.
- CURRENT -
- The horizontal movement of water.
- DAYBEACON -
- A fixed navigation aid structure used in shallow waters upon which
is placed one or more daymarks.
- DAYMARK -
- A signboard attached to a daybeacon to convey navigational
information presenting one of several standard shapes (square,
triangle, rectangle) and colors (red, green, orange, yellow, or
black). Daymarks usually have reflective material indicating the
shape, but may also be lighted.
- DEAD AHEAD -
- Directly ahead.
- DEAD ASTERN -
- Directly aft or behind.
- DEAD RECKONING -
- A plot of courses steered and distances traveled through the
- DECK -
- A permanent covering over a compartment, hull or any part of a
ship serving as a floor.
- DISPLACEMENT -
- The weight of water displaced by a floating vessel.
- DISPLACEMENT HULL -
- A type of hull that plows through the water, displacing a weight
of water equal to its own weight, even when more power is added.
- DOCK -
- A protected water area in which vessels are moored. The term is
often used to denote a pier or a wharf.
- DRAFT -
- The depth of water a boat draws.
- EASE -
- To slacken or relieve tension on a line.
- EBB TIDE -
- A receding tide.
- EVEN KEEL -
- When a boat is floating on its designed waterline, it is said to
be floating on an even keel.
- EYE OF THE WIND -
- The direction from which the wind is blowing.
- EYE SPLICE -
- A permanent loop spliced in the end of a line.
- FAST -
- Said of an object that is secured to another.
- FATHOM -
- Six feet.
- FENDER -
- A cushion, placed between boats, or between a boat and a pier, to
- FIGURE EIGHT KNOT -
- A knot in the form of a figure eight, placed in the end of a line
to prevent the line from passing through a grommet or a block.
- FLAME ARRESTER -
- A safety device, such as a metal mesh protector, to prevent an
exhaust backfire from causing an explosion; operates by absorbing
- FLARE -
- The outward curve of a vessel's sides near the bow. A distress
- FLYING BRIDGE -
- An added set of controls above the level of the normal control
station for better visibility. Usually open, but may have a
collapsible top for shade.
- FOLLOWING SEA -
- An overtaking sea that comes from astern.
- FORE AND AFT -
- In a line parallel to the keel.
- FORWARD -
- Toward the bow of the boat.
- FOULED -
- Any piece of equipment that is jammed or entangled, or dirtied.
- FOUNDER -
- When a vessel fills with water and sinks.
- FREEBOARD -
- The minimum vertical distance from the surface of the water to the
- GAFF -
- A spar to support the head of a gaff sail.
- GALLEY -
- The kitchen area of a boat.
- GANGWAY -
- The area of a ship's side where people board and disembark.
- GEAR -
- A general term for ropes, blocks, tackle and other equipment.
- GIVE-WAY VESSEL -
- A term, from the Navigational Rules, used to describe the vessel
which must yield in meeting, crossing, or overtaking situations.
- GRAB RAILS -
- Hand-hold fittings mounted on cabin tops and sides for personal
safety when moving around the boat.
- GROUND TACKLE -
- Anchor, anchor rode (line or chain), and all the shackles and
other gear used for attachment.
- GUNWALE -
- The upper edge of a boat's sides.
- HARBOR -
- A safe anchorage, protected from most storms; may be natural or
man-made, with breakwaters and jetties; a place for docking and
- HATCH -
- An opening in a boat's deck fitted with a watertight cover.
- HEAD -
- A marine toilet. Also the upper corner of a triangular sail.
- HEADING -
- The direction in which a vessel's bow points at any given time.
- HEADWAY -
- The forward motion of a boat. Opposite of sternway.
- HEAVE TO -
- To bring a vessel up in a position where it will maintain little
or no headway, usually with the bow into the wind or nearly so.
- HEEL -
- To tip to one side.
- HELM -
- The wheel or tiller controlling the rudder.
- HITCH -
- A knot used to secure a rope to another object or to another rope,
or to form a loop or a noose in a rope.
- HOLD -
- A compartment below deck in a large vessel, used solely for
- HULL -
- The main body of a vessel.
- HYPOTHERMIA -
- A life-threatening condition in which the body's warming
mechanisms fail to maintain normal body temperature and the entire
- INBOARD -
- More toward the center of a vessel; inside; a motor fitted inside
- KEDGE -
- To use an anchor to move a boat by hauling on the anchor rode; a
basic anchor type.
- KEEL -
- The centerline of a boat running fore and aft; the backbone of a
- KETCH -
- A two-masted sailboat with the smaller after mast stepped ahead of
the rudder post.
- KNOT -
- A measure of speed equal to one nautical mile (6076 feet) per
- A fastening made by interweaving rope to form a stopper, to
enclose or bind an object, to form a loop or a noose, to tie a small
rope to an object, or to tie the ends of two small ropes together.
- LEEWARD -
- The direction away from the wind. Opposite of windward.
- LEEWAY -
- The sideways movement of the boat caused by either wind or
- LINE -
- Rope and cordage used aboard a vessel.
- LOG -
- A record of courses or operation. Also, a device to measure speed.
- LUBBER'S LINE -
- A mark or permanent line on a compass indicating the direction
forward; parallel to the keel when properly installed.
- MAST -
- A spar set upright to support rigging and sails.
- MONOHULL -
- A boat with one hull.
- MOORING -
- An arrangement for securing a boat to a mooring buoy or a pier.
- MOORING BUOY -
- A buoy secured to a permanent anchor sunk deeply into the bottom.
- NAUTICAL MILE -
- One minute of latitude; approximately 6076 feet - about 1/8 longer
than the statute mile of 5280 feet.
- NAVIGATION -
- The art and science of conducting a boat safely from one point to
- OUTBOARD -
- Toward or beyond the boat's sides. A detachable engine mounted on
a boat's stern.
- OUTDRIVE -
- A propulsion system for boats with an inboard engine operating an
exterior drive, with drive shaft, gears, and propeller; also called
stern-drive and inboard/outboard.
- OVERBOARD -
- Over the side or out of the boat.
- PAINTER -
- A line attached to the bow of a boat for use in towing or making
- PAY OUT -
- To ease out a line, or let it run in a controlled manner.
- PENNANT (sometimes PENDANT) -
- The line by which a boat is made fast to a mooring buoy.
- PERSONAL FLOTATION DEVICE (PFD) -
- Official terminology for life jacket. When properly used, will
support a person in the water. Available in several sizes and types.
- PIER -
- A loading/landing platform extending at an angle from the shore.
- PILOTING -
- Navigation by use of visible references, the depth of the water,
- PITCH -
- 1. The alternate rise and fall of the bow of a vessel proceeding
- 2. The theoretical distance advanced by a propeller in one
- 3. Tar and resin used for caulking between the planks of a wooden
- PITCHPOLING -
- A small boat being thrown end-over-end in very rough seas.
- PLANING HULL -
- A type of hull shaped to glide easily across the water at high
- PORT -
- The left side of a boat looking forward. A harbor.
- PROPELLER -
- A rotating device, with two or more blades, that acts as a screw
in propelling a vessel.
- QUARTER -
- The sides of a boat aft of amidships.
- QUARTERING SEA -
- Sea coming on a boat's quarter.
- REEF -
- To reduce the sail area.
- RIGGING -
- The general term for all the lines of a vessel.
- RODE -
- The anchor line and/or chain.
- ROLL -
- The alternating motion of a boat, leaning alternately to port and
starboard; the motion of a boat about its fore-and-aft axis.
- ROPE -
- In general, cordage as it is purchased at the store. When it comes
aboard a vessel and is put to use, it becomes a line.
- RUDDER -
- A vertical plate or board for steering a boat.
- RUNNING LIGHTS -
- Lights required to be shown on boats underway between sundown and
- SCOPE -
- The ratio of the length of an anchor line, from a vessel's bow to
the anchor, to the depth of the water.
- SCREW -
- A boat's propeller.
- SEA ANCHOR -
- Any device used to reduce a boat's drift before the wind.
- SECURE -
- To make fast.
- SHACKLE -
- A "U" shaped connector with a pin or bolt across the
- SHEAR PIN -
- A safety device, used to fasten a propeller to its shaft; it
breaks when the propeller hits a solid object, thus preventing
- SHEET BEND -
- A knot used to join two ropes. Functionally different from a
square knot in that it can be used between lines of different
- SHIP -
- A larger vessel usually used for ocean travel. A vessel able to
carry a "boat" on board.
- SHOAL -
- An offshore hazard to navigation at a depth of 16 fathoms (30
meters or 96 feet) or less, composed of unconsolidated material.
- SLACK -
- Not fastened; loose. Also, to loosen.
- SLOOP -
- A single masted vessel with working sails (main and jib) set fore
- SPLICE -
- To permanently join two ropes by tucking their strands alternately
over and under each other.
- SPRING LINE -
- A pivot line used in docking, undocking, or to prevent the boat
from moving forward or astern while made fast to a dock.
- SQUALL -
- A sudden, violent wind often accompanied by rain.
- SQUARE KNOT -
- A knot used to join two lines of similar size. Also called a reef
- STANDING PART -
- That part of a line which is made fast. The main part of a line as
distinguished from the bight and the end.
- STAND-ON VESSEL -
- That vessel which continues its course in the same direction at
the same speed during a crossing or overtaking situation, unless a
collision appears imminent. (Was formerly called "the
- STARBOARD -
- The right side of a boat when looking forward.
- STERN -
- The after part (back) of the boat.
- STERN LINE -
- A docking line leading away from the stern.
- STOW -
- To pack or store away; especially, to pack in an orderly, compact
- SWAMP -
- To fill with water, but not settle to the bottom.
- TACKLE -
- A combination of blocks and line to increase mechanical advantage.
- THWART -
- A seat or brace running laterally across a boat.
- TIDE -
- The periodic rise and fall of water level in the oceans.
- TILLER -
- A bar or handle for turning a boat's rudder or an outboard motor.
- TOPSIDES -
- The sides of a vessel between the waterline and the deck;
sometimes referring to onto or above the deck.
- TRANSOM -
- The stern cross-section of a square-sterned boat.
- TRIM -
- Fore and aft balance of a boat.
- TRIMARAN -
- A boat with three hulls.
- TRIPLINE -
- A line fast to the crown of an anchor by means of which it can be
hauled out when dug too deeply or fouled; a similar line used on a
sea anchor to bring it aboard.
- TRUE NORTH POLE -
- The north end of the earth's axis. Also called North Geographic
Pole. The direction indicated by 000° (or 360°) on the true
- TRUE WIND -
- The actual direction from which the wind is blowing.
- TURNBUCKLE -
- A threaded, adjustable rigging fitting, used for stays, lifelines
and sometimes other rigging.
- UNDERWAY -
- Vessel in motion, i.e., when not moored, at anchor, or aground.
- V BOTTOM -
- A hull with the bottom section in the shape of a "V."
- VARIATION -
- The angular difference between the magnetic meridian and the
geographic meridian at a particular location.
- VHF RADIO -
- A very high frequency electronic communications and direction
- WAKE -
- Moving waves, track or path that a boat leaves behind when moving
across the waters.
- WATERLINE -
- A line painted on a hull which shows the point to which a boat
sinks when it is properly trimmed.
- WAY -
- Movement of a vessel through the water, such as headway, sternway,
- WHARF -
- A man-made structure bonding the edge of a dock and built along or
at an angle to the shoreline, used for loading, unloading, or tying
- WINCH -
- A device used to increase hauling power when raising or trimming
- WINDWARD -
- Toward the direction from which the wind is coming. Opposite of
- YAW -
- To swing off course, as when due to the impact of a following or
- YAWL -
- A two-masted sailboat with the small mizzen mast stepped abaft the