| Term | Description |
| Aback | Behind. Of the Sails pressed against the mast when the wind is on the wrong, inefficient side. Deliberately sailing aback is useful in close quarters sailing, such as wehn leaving a jetty or mooring back to top | |
| Abaft | Bearing towards the back. It is more behind a vessel than in front of it. Bearing more than 90 degrees on either side from dead ahead back to top | |
| Abeam | At 90 degrees to the vessel's direction or for and aft line back to top | |
| Aclinic Line | The imaginary line where the compass needle does not dip due to the earth's magnetism back to top | |
| Admiralty anchor | An anchor which can be folded for easy stowage. The shank and arms do not move, but the stock moves up to the right angles to the arms. back to top | |
| Admiralty sweep | A large cautious turm made to approach a gangway or to come alongside a vessel or jetty in a boat back to top | |
| Aft | The back of the boat or twoards the back of the boat back to top | |
| Age of the Tide | The interval between full moon or change of the moon and the highest high tide back to top | |
| Agonic Line | Lines on the earth's surface joining points where there is no magnetic variation back to top | |
| Ahull | A technique for riding out storms where you sail beam-on to strong winds and being driven before them while under no sails back to top | |
| Altazimuth | An instrument for establishing the altitude and asimuth of the stars and planets back to top | |
| Amplitude | In navigation, the arc of the horizon between east and a body when it is rising, and west and a body when it is setting back to top | |
| Anchor Bell | On large vessels a bell near the bows which is tolled at regular intervals during fog. The intervals denote the kind of vessel that is at anchor back to top | |
| Anchor Watch | When anchored in heavy weather, or where wind direction may change dangerously, it is advised to prepare an anchor watch of people who specifically check to see whether the anchor is dragging. They do this by taking bearingsor transits of objects on shore back to top | |
| Anemometer | A device of three or more cups on a spindle which measure the strength of the wind. back to top | |
| Angel on heel | The number of degrees of list a vesel has. The first indication that a sailing vessel may need to reef is too great an angle of the heel back to top | |
| Annual Varriation | The amount of by which variation changes up or down each year in a particular area. The annual increase or decrese is printed in the compass roses on each chart and may make a significant difference over a number of years back to top | |
| Anticlone | An area where the barometric pressure is high, usally indicating light, variable winds and fine weather back to top | |
| Antitrade | Wind that blows in the opposite direction from trade wind in an area where trade wind would normally be expected to occur back to top | |
| Apparent wind | The wind that results from the interaction of the true wind and the forward motion of the boat. When running at a speed of 8 knots with the wind blowing at 18knots, the apparent wind speed would be 10 knots back to top | |
| Arc of visibility | The sectors marked on a chart and showing where a light is visible from the sea back to top | |
| Aries | The star which for purposes of navigation is taken to be stationary in the sky. back to top | |
| Aspect ratio | The relationship between a sail's height and length along the foot. High aspect ration means a sail that is tall and nanrrow, low askpect ration is a short,squat sail. The phrase can also apply to centreboards and ruddersAstrolabe back to top | |
| Bilge | The space in the hull under the cabin sole back to top | |
| Catamaran | A fast sailing vessel with two hulls of similar shape and length separated by beams. The hulls have very little wetted surface and so are faster than a monohull of similar length back to top | |
| Centreboard | A board or metal plate lowered through the bottom of the boat to prevent the wind forcing the boat sideways. It may also increase the size of the keel back to top | |
| Clew of Sail | The aft lower corner of a triangular sail back to top | |
| Cockpit | The cockpit is the area usually aft of the main saloon, from which most sail controls are handled back to top | |
| Danforth | An anchor form in which the stock passes through the crown suitable for most types of sea bottoms back to top | |
| Davits | Two typically chrome poles that extend from the boat to hang the dinghy. They are most commonly found on catamarans and large yachts back to top | |
| Drogue | A drag device that is trailed to slow the catamaran's speed back to top | |
| Echo Sounder | A system where pulses are sent from a transducer in a vessel's hull to the sea bottom and returned. The time taken by the impulse is translated into depth. back to top | |
| EPIRB | Emergency position Indicating Radio Beacon. Can be a small floating radio transmitter for emergency use that can transmit a signal for up to 5 days back to top | |
| Equinox | Two times per year typically around March 21st and September 23rd where the length of the day equals the length of the night. Hence it is the beginning of a change of season. The equinox is marked by gale force winds known as the equinoctial gales. back to top | |
| Escape Hatch | The escape hatch is usally a deck hatch that is set into the side of the catamarn hull to be used for emergency exit back to top | |
| Fair Wind | A wind that allows a straight course to be set for one's destination without course changes back to top | |
| Fairlead | A pulley or fixed block which changes the direction of a line so that it leads easily to a winch back to top | |
| Flare | A pyrotechnic used for safety purposes can be of different color and typically used to draw attention back to top | |
| G.P.S | A G.P.S is the common terminology for a global positioning system back to top | |
| Gale | A wind averaging more than 30 knots. When it exceeds and avaerage of 50 knots it becomes a storm. back to top | |
| Gel Coat | The gel coat is the terminology used for the pigmented outside coat of a GRP boat (fiberglass) back to top | |
| Genoa | A headsail attached to the forstay, which is large enough to overlap the mast. back to top | |
| Halyard | A wire or rope for hoisting sails, flags etc.. back to top | |
| Head | The bow of a ship (2) A lavatory on the a boat or (3) the top part of a sail back to top | |
| Heel brace | The iron support at the bottom of a rudder back to top | |
| Heel | The angle of list of a boat under sail back to top | |
| Helm | The wheel or ship's steering back to top | |
| In ballast | Carrying ballast, but no cargo back to top | |
| Inboard | In the ship away from the sides or ends of the ship back to top | |
| Jackstay | Storng wires that follow the length of a vessel so that harnesses can be clipped to it in heavy weather. Protects passengers on cruising catamarans or monohulls from from falling overboard back to top | |
| Jib | A triangular sail, set to the forestay and not overlapping the mast back to top | |
| Keel | The main strength of a monohull. In the case of a yacht, it is the weight protruding below the hull which counterbalances the force of the heeling of the boat so that it produced forward motion back to top | |
| Keel | The main strength of any vessel, the force and aft timber which is laid down first in building,a and which takes all the frames that shape the boat. In the case of the yacht, the weight protruding below the hull which counterbalances the force of the heeling of the boat and so produces forward motion back to top | |
| Ketch | A two-masted yacht with the the after mast stepped in front of the steering position back to top | |
| Kevlar | A Material used in the sails of racing yachts which has great stability and will hold its shape in changing wind conditions back to top | |
| L.O.A | Stands for Length overall and usually can be found in the specifications of a yacht back to top | |
| Lazyjacks | Lines rigged so that the mainsial will gather in them when geing dropped. They run from the mast to the boom back to top | |
| Leeward | Away from the wind, in the direction the wind blows on the sheltered side back to top | |
| Magnetic bearing | A bearing taken without corrections made to it from a compass error back to top | |
| Main stay | The line supporting the mast back to top | |
| Mainsail | The sail that is aft of the mast and attached to it. It is typically the larget sail on a vessel back to top | |
| Masthead | The top of the mast, the area for electronic wind sensors, VHF and other equipment back to top | |
| Motor Sailer | The Motor Sailer is a term used to describe a vessel that is designed and equiped with rig and sails but which also has a large engine or engines that achieves good travel speeds by engine alone back to top | |
| Nautical mile | Descriped as One minute of latitude at the equator, 1852 metres or 6077 feet back to top | |
| Navigation lights | Lights to demonstrate the existence of the vessel, its type and its course. Red for port side (left) and Green for starbord back to top | |
| Observation spot | A position of the precise latitude and longitude back to top | |
| On the wind | Sailing close-hauled, close to the wind back to top | |
| Osmosis | Osmosis is when water penetration occurs through the gel coat and into the laminate below. Osmosis is marked by blistering back to top | |
| Outhaul | The control line which loosens or tightens the foot of a sail, particularly the mainsail. It is very important because it matches the shape of the sail to the strength of the wind back to top | |
| Outrigger | A float on one or both sides of a main hull to prevent capsize. back to top | |
| Parachute Anchor | A parachute anchor is used to stop drifting back to top | |
| Pelorus | A rotating pointer over a fixed compass dial for taking bearing points of the land back to top | |
| Plow anchor | Also known as a CQR which is the shape of a triangle with a mounted main arm which allows for easy launch. CQR stands for Coastal Quick Release back to top | |
| Port Side | The left side of the vessel when facing towards the bow back to top | |
| Proa | A two hulled craft with a main hull and outrigger back to top | |
| Pulpit | Typically made of stainless steel around the bows of a yacht back to top | |
| Pushpit | The United Kingdom terminology for a stanless steel guard around the stern of a vessel. In U.S english called the Sterm pulpit back to top | |
| PVC foam | PVC is the acronynm for Ployvinyl chloride foam. A tough, resilient foam that is not affected by water back to top | |
| Quarter | To be on the quarter means to be at 45 degrees aft of the beam back to top | |
| Racon | A radar beacon which emits its signal when triggered by beams from a radar back to top | |
| Radar clearing line | A radar range to provide a safe distnace off when travelling along a coast back to top | |
| Radar reflector | Metal apparatus with many surfaces which reflects radar signals on the vessel which would be difficult to detect back to top | |
| RDF | Radio direction finder - it is a radio received used to determine the direction of a radio wave source back to top | |
| Reef | The action of reducing the sail so that a sailing vessel in not overpressed in heavy weather back to top | |
| Scend | The depth below mean water level that the trough of a wave descends back to top | |
| Schooner | A fore and aft rigged vessel with two or more masts and the second mast taller than the first mast back to top | |
| Sextant | A navigator's instrument for measuring angles vertically - such as stars, lighthouses and landmarks back to top | |
| Spar | Any mast, spinnaker pole, boom etc.. back to top | |
| Spinnaker | A racing sail, which is cust very full and sets on the opposite side of the boat from the main sail when running or reaching back to top | |
| Stays | The wires which suport the mast for and aft. The lines are called forstay, backstay and intermediate or baby stay back to top | |
| Stern | The after part of a ship or boat back to top | |
| Tabernacle | A hinged upright, supporting frame to house the foot of a mast back to top | |
| Tender | A motor vessel which is used to connect a larger vessel and the shore. Typically larger than a dinghy used on sailboats. The tender terminology is most commonly used with motor vessels (large yachts) back to top | |
| Tiller | A wood or metal arm attached to the rudder for steering back to top | |
| Trade winds | Winds which blow from a consistent direction at certain times of the year. They were given this name due to the fact that they allowed the trade to expand througout the world back to top | |
| Traveller | A metal car which slides along a track and takes the pulley controlling a sheet back to top | |
| Trimaran | A vessel with three hulls, usually a large centre hull and a smaller but equal sized hull on each side back to top | |
| Under bare poles | The term used to describe that the vesell is without sails set back to top | |
| Under way | When a vessel is not on anchor, tied up, aground or connected to the shore. It does not mean however that the boat is moving back to top | |
| Vang | A fitting that controls the angle of the boom to the mast back to top | |
| Veer to | Let out a line or cable or of the wind, to change direction clockwise back to top | |
| VMG | Velocity made good. VMG takes into account current, tide, leeway, boat speed, course sailed and any other factor which may affect the speed with which a yacht is approaching a mark. It is sometimes referred to as speed over ground back to top | |
| Wake | Distributed water extending from the stern of a vessel when moving. The wake also consists of waves formed at the bow and stern and these can be seen at very great distances from the source in flat water back to top | |
| Water line | The painted water line is theoretically the line in which the vessel will float. The actual waterline is where a vessel floats under different loads back to top | |
| Windlass | A drum driven by motor power or man power which when it rotates winds in wire or rope and so hauls or lifts - typically used to descriped the hoisting mechanism for the anchor back to top | |
| Xylocaine ointment | A recommended ointment to have on board in emergency medical kits for burns back to top | |
| Yacht | A vessel larger than a boat and smaller than a ship back to top | |
| Yard | A spar or mast for attaching an extending sails back to top | |
| Zephyr | A gentle breeze back to top | |
| Zulu | Universal Time formely Greenwich Mean Time back to top | |
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