General glossary

This glossary contains those words and phrases in general maritime usage. Most are highly specialised so that their meaning is clear and unambiguous. Whereas the landlubber might talk of the 'left' and 'right' side of a vessel the mariner will· talk only of 'port' and 'starboard' to identify without doubt which is which. And some words are confusing – but not to a seasoned salt. Sailors know that a 'sheet' isn't something you spread on a bed (actually a 'berth' or 'bunk' afloat) but a rope that has a specific purpose when it comes to trimming the sails.

Aback:· When a sail is sheeted 'aback' it's hauled to windward so it appears to be set inside out. This is a powerful manoeuvring tool which moves the bow to leeward, perhaps when tacking.· 

 Abeam:· Situated directly to one side of the boat.

Aft: The rear end of a boat. Towards the stern.

Ahead: In front of the boat.

Aka: The beams that connect the three hulls of a trimaran.

Ama: The outer hulls of a trimaran. Also, the port hull of a double canoe. (see catamaran) 

 Amidships (Midships): In the middle of the boat. To put the helm amidships is to centre the wheel or tiller so that the boat steers straight ahead.

Aspect Ratio: The ratio between height and width·– usually used to describe sails and foils such a daggerboards and rudders. Long and narrow are said to be of 'high' aspect ratio. 

 Astern:  Behind the boat.

Athwartships: Lying or acting sideways across a boat.

Baby stay:  Also called 'inner forestay' by the less childishly inclined. A stay rigged between the forestay and the mast

Back: To back a sail is to have it sheeted on the windward side so that the sail's drive pushes a boat's bow around. (see 'aback') Such a sail is said to be 'backwinded'.

Backstay: Part of the standing rigging. A wire (or wires, since double backstays are common) that opposes the forces imposed by the 'forestay'.

Barber hauler:  A line used to change the lead of a sheet.

Bare poles: To sail downwind (usually in very heavy weather) with no sails set and the engine off. Not something you should wish for. 

 Batten:· A thin strip of a flexible material – these days usually plastic or glassfibre – to stiffen a sail and help support its 'roach'.

Beam: The maximum width of the boat. On older boats, something you can knock your head on.

Beam Reach: Sailing with the wind 'abeam' - i.e. coming directly from one side.

Bear away: To turn a sailboat away from the wind's direction.

Beat: To sail as close to the wind's direction as possible. Also called 'close hauled'.

Belay: To make fast. Usually meant for sheets and halyards.

Belaying pin: Vertical pin to which halyards and other parts of the running rigging are fastened – i.e. 'belayed'. 

 Bend: A knot for attaching two ropes together or for tying a rope to an object.

Berth: A place to moor, or for someone to sleep.

Bilge keel: A keel fitted near the bilge·– outboard on the bottom rather than on the centreline. A bilge keeled yacht has two bilge keels, one to either side.

Bitts: Stout posts arranged in pairs on the foredeck, used for securing mooring· or other lines.

Bitter end: Beer drinkers shouldn't panic – this is just the very end of a rope.

Block:· A pulley.

Bobstay:· A stay which braces the 'bowsprit' to the hull just above the waterline or some point low on the stem.

Bollard:· A strong point to secure a mooring warp, either on the dock or the boat.

Boom: A spar that supports and extends the bottom edge (the 'foot') of a sail·– most commonly the mainsail.

Bottle screw:· Rigging screw' or 'turnbuckle'. These are double ended screws which tension the standing rigging.

Bow:· The forward part of the boat. Port and starboard bows are either side of the stem.

Bow Roller:· A fairlead for the anchor warp, attached to the vessel.

Bower anchor: A vessel's main anchor.

Bowsprit:· A pole extending forward of the bow, from which to attach a headsail's 'tack'.

Bridgedeck: The connecting platform that joins catamaran hulls.

Bridle:· A pair of lines attached to an anchor warp or drogue line, intended to divide the load.

Broach (Broaching): To lose control and slew around so that the boat lies side-on to the waves.

Broad reach:· A point of sail where the wind is from aft of the beam bur not directly (or nearly) astern.

Bulkhead:· A structural lateral (athwartships) partition inside a hull.

Cable:· A rope or chain on the anchor. One-tenth of a nautical mile.

Capsize:· Whoops! A boat turned upside down or rolled is said to have capsized. Not considered much fun. 

Car:· A movable fairlead for a sheet, running athwartships for a mainsail and fore and aft for headsails.

Catamaran:· A boat with two separate hulls.

Catenary: The curve formed by a rope or chain suspended between points due to its weight. The shape taken up by an anchor rode is a good example.

Centre of effort: The geometric centre of a sail plan, used in stabilty calculations and other computatons as a matter of convenience. The actual 'centre of aerodynamic force' depends largely on sail trim and is almost impossible to predict.

Centre of lateral resistance: The geometric centre of a boat's immersed form, as seen from the side. This is another convenient approximation since, as above, the actual 'centre of hydrodynamic force' (the point at which a boat's resistance to leeway can be said to act) is again almost certainly elsewhere, 

Centreboard:· A pivoting board that can be lowered into the water to help resist leeway.

CEVNI:· Code European de Voies de la Navigaton. This is an endorsement to the ICC allowing the holder to operate on European inland waterways.

Chain Plate:· A metal plate set on each side of a hull to which the shrouds are attached.

Cheek block:· A hollowed-out cheek containing a sheave, with one side flattened so that it can be permanently ftted to a mast or to the deck.

Chine: The angle formed between flat hull panels where they come together.

Cleat:· Used to secure lines. There are various different types.

Clevis pin:· The removeable strong steel pin (usually stainless) which closes the U-shaped fork on the end of a rigging screw. 

Clew:· The aft lower corner of a sail, where the sheet is bent on, if the sail is not set on a boom.

Close hauled:· See 'beat'.

Close reach: A point of sail somewhere between a beat and a beam reach.

Coachroof:· The raised part of the deck structure above the accommodation.

Coaming:· A vertical barrier, often around cockpits and hatches, intended to keep water out.

Cockpit:· The external control centre of a boat, for steering and sail trim.

Colregs: Colloquial expression for the International Regulations for the Prevention of Collision at Sea, IRPCS.

Companionway: Entrance to the accommodation, normally at the forward end of the cockpit.

Counter: The overhanging part of the stern, particularly aft of the rudder.

Course: The direction in which a vessel is pointing or heading.

Cracking off:· A colloquialism meaning 'bearing away from the wind'.

Crosstree: A strut fitted on the mast athwartships, opposing the inward thrust of the shrouds.

Cruising Chute: See 'spinnaker'.

Cutter: A type of rig which carries a pair of headsails, one set behind the other.

Daggerboard:· A non-pivoting board that's lowered through a slot in a hull. Its purpose is to resist leeway.

Dead reckoning: The type of navigational computation which attampts to establish a position by the course steered and distance run through the water.

Displacement: The weight of water displaced by a vessel afloat.

Displacement Mode: When a vessel is operating without benefit of hydrodynamic lift· – i.e., not planing.

Downhaul: A rope which pulls down the tack of a sail or the forward part of a spar.

Downtide, Downstream:· To run in the same direction as the tide or stream.

Downwind: Sailing in the same general direction of the wind.

Draught (or 'draft'): The measurement between the waterline and the lowest point of the keel.

Drogue: A drag device, towed astern to slow and help control a boat in heavy weather.

DSC:· Digital Selective Calling. A system whereby a VHF radio transmitter can make an automatic digitized call to a selected station.

Escape hatch:· A watertight hatch fitted into the side of a multihull's hull, that allows exit and entry after capsize.

Eye splice: An eye formed in a rope's end by weaving the strands through one another.

Fairlead: A deck fitting used to lead a rope towards a winch or cleat to minimise chafe.

Fairway: The main channel into the harboar. That part of an approach channel lying outside of a harbour entrance.

Fenders: Soft (often air-filled) pads hung over a boat's sides to protect it from anything alongside.

Fluke: The part of an anchor which digs into the sea bed.

Following sea: Waves coming from astern.

Foot: The bottom edge of a sail.

Foot block:  See 'Cheek block'

Forefoot: The point where the lower part of the stem meets the keel.

Foresail: A sail set on the 'forestay' (see below). Usually smaller than a 'genoa' and often called a 'jib'.

Forestay: The foremost part of the standing rigging, leading from high on the mast to an attachment point on the centreline at deck level. If often carries a roller reefing gear.

Freeboard: The vertical distance from the waterline to the deck.

Furl: To furl a sail is to roll it up. Note that 'furling gears' are not necessarily 'reefing gears'.

Genoa:· Any 'headsail' sail large enough to overlap the mast.

Gooseneck: An articulated joint between the boom and mast.

Gybe: When sailing downwind, to alter course so the sails set on the other side of the boat. Also spelled 'jibe'.

Halyard:· The rope used to raise and lower a sail.

Head: A triangular sail's top corner. The upper edge of a quadrangular sail. 

Heading:  The direction in which you are sailing or would like to sail.

Heads:  In the US more correctly 'head'. A universal name for a sea toilet. It came into use because in sailing vessels without a toilet, crew went to the bow for that purpose.

Headsails:  A general term describing any triangular sail set forward of the mast.

Heel: The way a boat leans over, either from the wind or by a shift in weight. 

Helm: The steering mechanism. The tiller or wheel. The person steering (of either gender).

Helmsman: The person steering a vessel.

Highfield lever:  A tensioning device which can be rapidly disconnected.

Hounds:  The point on the mast where the lower shrouds are attached.

Hove-to:  Lying nearly stationary in the water, usually with the foresail 'aback'.

 ICC: International Certificate of Competence.

IRPCS:  See Colregs.

Jib:  A headsail that does not overlap the mast. Usually attached to the forestay.

Jibe: See 'gybe'.

Kedge:  A secondary anchor.

Ketch:  A two-masted sailboat with the shorter mast towards the stern.

Knot:  One nautical mile per hour. The oft-heard phrase 'knots per hour' is nonsensical since it would mean 'one nautical mile per hour per hour'.

Lanyard: A short, light length of cord or rope used as a safety line to prevent loss of something overboard, such as a line to raise a bucket of water from the sea or to fasten a knife.

Lee:  The protected downwind side of an object.

Lee Helm: A balance between the hull shape and sailplan that will cause a boat to 'bear away' if the helm is released. Throroughly dodgy.

Lee Shore:  Land that lies to 'leeward' of yourself. Not good news in heavy weather.

Leech:  The after edge of a sail.

Leeward: The side of the boat facing away from the wind.

Log: (1) An abbreviation for 'log-book', in which all necessary navigational information is recorded.

Log: (2) Once an reference to a wedge of wood which was streamed astern to determine a boat's speed. Now almost invariably an electronic instrument that does the same job.

Luff:  The foremost edge of a sail. 'To luff' means that edge starting to flutter when you sail too close to the wind.

Marina:  A sheltered area with berths and other facilities for boaters.

Midships/amidships:  The central area of a vessel.

Mizzen: The fore-and-aft sail set on the after mast of a yawl or ketch.

MOB:  Man overboard. Try never to be one on them.

Nacelle:  A lowered area on the underside of a catamaran's bridgedeck.

Neap tides: Or simply 'neaps'. The lesser tide experienced every two weeks when the sun and moon are pulling against one another at half-moon.

Painter:  Not a man with a brush but a line for securing the bow of a dinghy or liferaft to tow it astern of a yacht or make fast.

Parachute Anchor:  A sea anchor intended to minimise a boat's drift and hold it head to wind.

Pinch, to: To sail so close to the wind that the sails lose their drive, even though they may still be drawing.

Pitching:  Fore-and-aft rocking motion.

Pitchpole:  A form of capsize end-over-end or perhaps a little diagonally. Not reported to be a lot of fun.

Pivot Point:  The point around which a boat swivels when it is steered.

Planing: Operating a vessel fast, with the hull skimming over the surface of the water rather than through it.

Pointing:  Sailing as close to the wind as possible. A boat that 'points high' will sail closer than one that 'points low'.

Pontoon:  A floating platform used for mooring boats.

Pooped, to be:  If the sea breaks over the stern and into the cockpit, she is pooped and the helm very wet.

Port:  The left hand side of a vessel when facing the bow. Also a safe haven as in 'any port in a storm'.

Port side to:  Placing the port side of the vessel against a quay to pontoon.

Pounding:  The action of the seas 'pounding' on the underside of the hull or bridgedeck. Also known as 'slamming'. Not to be relished.

Pre-bend:  A bend in the mast set by tensioning the standing rigging. Pre-bend stiffens the spar and assists mainsail shape.

Preventer:  A line rigged to hold the boom forward, thereby guarding against an accidental gybe.

Prodder:  See 'bowsprit'.

Quarter:  The side of a vessel between amidships and the stern.

Rake:  The angle of the mast from the vertical.

Reach:  See 'beam reach', 'broad reach' and 'close reach'.

Reef:  To reduce sail area.

RIB: A rigid inflatable boat. Usually a small powerboat.

Roach:  The sail area that extends aftwards behind the straight line between the head and clew of a fore-and-aft sail. Usually refers to the mainsail.

Rode:  A tether of some sort that connects a boat to an anchor, drogue or sea anchor. It can be of chain or rope or a combination of both. The last is a good compromise for multihulls.

Roller Reefing:  A mechanism to reduce sail by winding it up around a small diameter spar – usually of aluminium.

Rudder post:  The rudder shaft or stock.

Running:  Sailing downwind – i.e. with the wind coming from astern.

Running Backstay:  A backstay that can be slackened or tautened, as required, and can be done with tackles, winches or with a Highfield lever.

Running Rigging:· Lines used to control sails, spars and mast bend. Usually rope but sometimes wire.

Samson Post: A strong post for attaching anchor or mooring lines to.  A single bitt.

SAR:  Search and rescue.

Screw:  Colloquial term for propeller.

Seacock:  A valve on a through-hull skin fitting which can be opened and closed as required.

Shackle:  A horseshoe shaped metal link which can be opened or closed. The most common is a U-Shaped, the open part of the U being closed by a threaded pin.

Sheets: The primary control for the set of a sail – attached to the clew.

Ship, to:  To set a component in its working position.

Shock cord:  A bungee. An elasticated cord made of rubber strands inside a textile cover.

Shrouds:  The standing rigging – usually wire – that gives a mast athwartships support.

Skeg:  A fixed fin used to support the leading edge of a rudder.

Skin fitting:  Through-hull fitting.

Sloop:  A single-masted sailboat which carries a single headsail.

Spar:  A general term that includes masts, booms, gaffs, and spinaker poles, amongst others.

Spinnaker:  A lightweight balloon type sail that's set 'flying' – that's to say not attached to a stay. Usually for downwind sailing but some types also capable of 'reaching'.

Spinnaker pole:  A pivoting pole to which the 'tack' of a spinnaker is attached.

Spreader:  The struts used to spread the shrouds to a wider angle at which the shroud meets the masthead.

Spring tides:  The greater high tides that occurs when the gravitational pull of the sun and moon coincide.

Stanchion:  Stainless steel, aluminium or bronze vertical posts providing support for the guardrails at the deck edge.

Starboard:  The right hand side of a boat looking forward.

Stay:  Part of the standing rigging. A wire which supports the mast.

Staysail:  The aftmost headsail of a 'cutter' rig.

Steerage Way:  The minimum speed required to maintain control of a boat via the rudder.

Stem:  The bow or cutwater. In a wooden vessel it's the vertical timber to which the planks are attached.

Stern:  The rear end of a boat.

Stern post:  The structural timber at the after end of a wooden hull on which the rudder is frequently hung.

Stream:  The flow or movement of water, whether caused by current or tide.

Surf, to:  To slide down a wave in the manner of a surfer.

Tack:  The bottom front corner of a sail. Also, when going to windward, to alter course to put the wind on the other bow. To sail a boat's bow through the wind.

Tacking:  The zig-zag course of a boat sailing upwind.

Tackle: Pronounced 'taykle'. An arrangement of blocks and rope to produce mechanical advantage. Note that the phrase 'block and tackle' is incorrect, since tackle means both.

Telltale:  A lightweight ribbon or other type of streamer that indicates the airflow over a sail.

Terminal:  In the standing rig the proprietary fitting worked into the end of a wire rope by which the shroud or stay is attached to the mast or the boat.

tideway:  Channels where the effects of tidal stream can be felt.

Tiller:  A handle or lever that operates the rudder for steering.

Toe-rail:  A raised edging around a deck's perimeter. It may be of wood, aluminium, or of glass reinforced plastic.

Topping Lift:  A line that takes the weight of a boom, preventing it from dropping.

Topsides:  Sides of the boat between the waterline and the deck.

Trampoline:  A lightweight netting or fabric walkway between beams and/or hulls on a catarmaran or trimaran.

Transducer:  A sensor for an echo sounder or for any other navigational instrument.

Transom:  A transverse flat section of hull across the stern of a boat.

Trimaran:  A sailboat or any vessel with three hulls.

Trim tabs:  Adjustable horizontal plates on the stern of a power boat which help control trim.

Uptide:  Upstream, in a direction against the flow of water.

Vang:  A tackle or other device between the mast and boom intended to hold the boom down. It controls mainsail leech tension. Also known as a 'kicking strap' or 'kicker'.

Wake:  The trail of disturbed water left behind a moving boat.

Warp:  A rope used for mooring or anchoring.

Waterline:  The fore-and-aft line at which a boat floats.

Weather (side):  The side onto which the wind blows.

Weather helm:  The tendency of a sailboat to come head into the wind.

Wetted surface area:  The area of the immersed portion of the hull.  

Windage:  The amount by which a vessel is affected by wind. Also the areas of hull and superstructure that contrbute to this effect.

Windward:  Towards the deirction from which the wind blows.

Windward Berth:  A berth that a boat tends to be blown away from.

Wing Mast:  A mast elongated in the fore-and-aft direction to form a rigid aerofoil. Such masts invariably rotate.

Yaw:  To veer continually from one side of the course to the other.

Yawl:  A two-masted sailing vessel whose mizzen is stepped abaft the sternpost. The mizzen of the yawl is generally smaller than a ketch's.