daggerboard:

centerboard that does not pivot

a board dropped vertically through the hull to prevent leeway. May be completely removed for beaching or for sailing downwind.

danger bearing:

a line drawn on a chart from a visible, charted object to a navigational hazard. The navigator uses the magnetic bearing of this line to warn him when his course is leading him too close to the danger.

daymark:

the colored and numbered or lettered sign placed on many beacons to identify them. Most daymarks are coated with reflective material to make them visible in a searchlight beam at night.

deadlight:

either a cover clamped over a porthole to protect it in heavy weather or a fixed light set into the deck or cabin roof to provide light below.

dead reckoning:

the process of predicting and fixing position by course, speed, and distance run.

deadrise:

the angle at which the bottom rises from where it joins the keep to the turn of the bilge, or chine.

deck plate:

small fitting set flush with the deck, forming the upper extremity of a piping system.

deviation:

compass error produced by magnetic disturbances aboard ship.

dinghy:

small open boat for sailing, rowing, etc.

a small open boat, usually carried aboard a yacht for going ashore.

ditty bag:

a bag used by sailors to hold gear needed for repairs on sails or rigging.

dodger:

a screen, usually fabric, erected to protect the cockpit from spray and wind.

dorade ventilator:

a deck box with a cowl and an internal arrangement that allows air but not water to enter the cabin.

doubler:

a wood or metal plate bolted beneath a mounting surface for reinforcement.

downhaul:

a line used to pull a spar, such as the spinnaker pole, or a sail, particularly the mainsail, down

a control line that adjusts and tensions the luff of a sail.

downwind:

sailing in the same direction as the wind.

draft:

the depth a vessel extends below the waterline.

DR:

dead reckoning, deduced reckoning; your position based on speed, direction, and time.

drift:

the leeway, or movement of the boat, when not under power, or when being pushed sideways while under power

the speed in knots, of a current.

dry sailing:

when boats, especially smaller racers, are kept on shore instead of being left anchored or moored, they are dry sailed. The practice prevents marine growth on the hull and the absorption of moisture into it.

ease:

to loosen or let out.

ebb:

tide passing from high to low, with the current going out to sea

the tidal movement of water away from the land and toward the sea, as in ebb current; the falling of the water level from high tide to low tide, as in ebb tide.

engine grounding point:

a common terminal point on the engine block to which the negative battery terminal, the negative bus bar and the bonding system are connected.

eye:

a loop in a line that has been seized, spliced or knotted.

eye of the wind:

direction from which the wind is blowing.

eye splice:

a permanent loop made at a rope's end by weaving unlaid strands into the standing part of the line.

fairlead:

fitting through which a line runs easily

a fitting used to alter the direction of a working line, such as a bullseye turning block, or anchor chock.

fall off:

turn away from the direction of the wind.

fathom:

a nautical measure equal to six feet; used for measuring water depths, and also for indicating the lengths of lead lines, cordage and anchor chains.

fathom line:

a line on a chart connecting equal water depths and thereby marking the contours of underwater geographical features.

feathering:

sailing upwind so close to the wind that the forward edge of the sail is stalling or luffing, reducing the power generated by the sail and the angle of heel.

fetch:

the distance along open water or land over which the wind blows; to achieve a desired destination under sail, particularly with an adverse wind or tide.

fid:

a tapered, pointed wooden tool for insertion between strands of rope while splicing, sometimes having a hole in the blunt end for insertion of rope.

fiddle:

strip around a table to prevent items from falling off when the boat is at a heel

a rack or bar used to prevent dishes, pot, and other objects from sliding off a counter, table or stove.

fin keel:

a deep narrow keel found on most modern ocean-racing boats that creates less drag than do longer conventional keels.

fix:

a boat's position as marked on a chart, established by taking bearings on two or more known landmark's (visual fix) or two or more radio sources (electronic fix).

flashing:

description of a light-fixed on a navigation aid-that flashes on and off. The period of light is always briefer than the period of darkness.

flood:

the movement of water toward the land and away from the sea; the rising of the water level from low tide to high tide.

flying bridge:

a raised platform that affords unobstructed vision for steering and navigation.

fo'c'sle:

an abbreviation of forecastle. Refers to that portion of the cabin which is farthest forward. In square-riggers often used as quarters for the crew.

foot:

to make speed-said of a sailboat.

fouled:

entangled or clogged, caught or twisted up.

fore-and-aft:

lengthwise

a boat's longitudinal axis.

fore-and aft-rig:

sail set in a fore-and-aft line. Not square-rigged.

forefoot:

the forward portion of a boat's hull below the waterline.

forepeak:

the compartment farthest forward in the bow of the boat. Often used for anchor or sail stowage.

forestay wire:

sometimes rod, support for the mast, running from the bowsprit or foredeck to a point at or near the top of the mast.

foretriangle:

on a sailboat, the triangle formed by the headstay, the front of the mast, and the deck.

freeboard:

the distance between the deck and the waterline. Most often it will vary along the length of the boat.

furl:

tightly roll up a sail

to roll, fold, or wrap an expanse of cloth-such as a sail, a flag or an awning-close to or around a spar, staff or stay.

gaff:

a spar used to support the top of a mainsail or a pole with a hook end used for hauling fish onboard

a spar to support and spread the head of a sail of four generally unequal sides. A sail so rigged is gaff-headed.

gain control:

a device installed on marine radio receivers to improve the clarity of radio signals; also, used for the same purpose on radar sets.

gale:

a range of winds from 28 to 47 knots.

galley:

a boat's kitchen.

genoa:

a large headsail set on the headstay and overlapping the mainsail.

gimbals:

a device that suspends a compass so that it remains level

pivoted mounts that enable the object they support (a compass, stove, lamp, etc.) to remain level when the boat does not.

going to weather:

to sail against the prevailing wind and seas.

grab rail:

a securely mounted handhold on or below deck.

great circle:

a course plotted on the surface of the globe that is the shortest distance between two points.

gooseneck:

the fitting that connects the boom to the mast.

Greenwich meridian (also prime meridian):

the meridian designated as 0 degrees that runs through Greenwich, England, and serves as the base line for measurements of longitude.

grommet:

rope or brass ring in a sail or piece of canvas.

ground tackle:

anchor and anchor gear.

gudgeon

the socket for the pintle of a rudder.

gunwale:

most generally, the upper edge of the side of a boat.

guy:

a line used to control the end of a spar. A spinnaker pole, for example, has one end attached to the mast, while the free end is moved back and forth with a guy.

gybing:

turning the boat so that the stern (back of the boat) crosses the wind, changing direction.