abaft the beam-- behind a perpendicular line extending out from the middle of the boat
Abeam - At right angles to, or beside, the boat
Aboard - On or in the boat
Aft - towards the stern of the boat; to move aft is to move back
Aground - When the hull or keel is against the ground
Aloft - overhead, above
Amidships - the middle of the boat
Anchor - An object designed to grip the ground, under a body of water, to hold the boat in a selected area
Anchorage -- a place for anchoring
Apparent wind - The perceived wind direction experienced on a moving boat.
Astern -- in the direction of, or behind, the stern

Backstay: A wire support for the mast, usually running from the stern to the head of the mast.
Backwinded- when the wind hits the leeward side of the sails
Bail - to remove water from the boat
Bailers: Openings in the bottom or transom of a boat to drain water when sailing.
Bale A fitting on the end of a spar, such as the boom, to which a line may be led.
Ballast - weight in the lower portion of a boat, used to add stability (In a multihull - useless crew on other boats.)
Bar-- a shoal area at the river or inlet (Also site of post-race discussions / lies / exaggerations / bet-collections)
Barber Hauler, A line attached to the jib or jib sheet, used to adjust the angle of sheeting by pulling the sheet toward the centerline of the boat.
Batten: A thin wooden or plastic strip inserted into a pocket on the back part (leech) of a sail, to assist in keeping its form
Beam -- the greatest width of the boat, usually in the middle.
(Also Amateur Radio - an antenna "An aluminium thing avec elements - the more of which the merrier; the higher the better."
Also (at times) falsely declared to Customs Officers to be a Crocodile Spear...)
Beam reach - a point of sail where the boat is sailing at a right angle to the apparent wind.
Bear Away/Bear Off: See Head Down.
Bearing - a compass direction from one point to another
Beating (Close Hauled, On the Wind): Sailing toward the wind source, or against the wind, with the sails pulled in all the way, tacking as you go, to reach a destination upwind.
Belay - to make secure
berth -- sleeping bunk aboard the boat
bight -- a loop in a rope -or- a bend in the shoreline
Bilge - the lowest part of a boat, designed to collect water that enters the boat
Binnacle -- compass stand
bitter end -- the final inboard end of chain or line
Blanketing: a tactical manuever whereby a boat uses its sails to blanket the competitor's wind, slowing him down.
Block - a pulley
bluewater sailing -- open ocean sailing, as opposed to being in a lake or sound
Boat Hook - a device designed to catch a line when coming alongside a pier or mooring.
Bobstay Wire stay underneath the bowsprit; helps to counteract the upward pull exerted by the forestay.
Bolt Rope - a rope sewn into the luff of a sail for use in attaching to the standing rigging
Boom - the horizontal spar to which the foot of a sail is attached.
Boom Crutch Support for the boom, holding it up and out of the way when the boat is anchored or moored. Unlike a gallows frame, a crutch is stowed when boat is sailing.
Boom Vang A system used to hold the boom down, particularly when boat is sailing downwind, so that the mainsail area facing the wind is kept to a maximum. Frequently extends from the boom to a location near the base of the mast. Usually tackle- or lever-operated.
Boom: the horizontal spar on the bottom of the mainsail behind the mast.
boot stripe -- a different color strip of paint at the waterline
Boot top A stripe near the waterline.
bow -- forward end of a boat
Bowsprit A short spar extending forward from the bow. Normally used to anchor the forestay.
Breast line - a docking line going at approximately a right angle from the boat to the dock
Bridge deck The transverse partition between the cockpit and the cabin.
Bridle A short length of wire with a line attached at the midpoint. A bridle is used to distribute the load of the attached line. Often used as boom travelers and for spinnaker down hauls.
bright work -- varnished woodwork or polished metal
broach -- a turning or swinging of the boat that puts the beam against the waves, creating a danger of swamping or capsize
Broad reach - a point of sail where the boat is sailing away from the wind, but not directly downwind
bulkhead -- a partition below decks Bulkhead An interior partition commonly used to stiffen the hull that separates one part of the vessel from another. May be watertight.
Bullseye A round eye through which a line is led, usually in order to change the direction of pull.
Bulwark A vertical extension above the deck designed to keep water out and to assist in keeping people in.
bulwarks -- rail around the deck
bunk - Sleeping accomodation (seldom used while racing…)
Buoy - an anchored float marking a position or for use as a mooring
By the Lee: Sailing downwind with the wind blowing over the leeward side of the boat, increasing the possibility of an unexpected jibe.

cabin sole --the bottom surface of the enclosed space under the deck of a boat
Can - a type of navigation buoy
canvas -- old slang term for sail. Originally sails were made of canvas.
Cap A piece of trim, usually wood, used to cover and often decorate a portion of the boat, i.e., caprail.
Capsize - to turn a boat over
Cast Off - to release lines holding boat to shore or mooring, to release sheets
catamaran -- twin hulled boat
Catboat - a one sail sailboat
celestial navigation -- to calculate your position using time, the position of celestial bodies, and mathematical tables
Centerboard A board lowered through a slot in the centerline of he hull to reduce sideways skidding or leeway. Unlike a daggerboard, which lifts vertically, a centerboard pivots around a pin, usually located in the forward top corner, and swings up and aft.
Chafe - damage to a line caused by rubbing against another object
chafe gear -- gear used to prevent damage by rubbing
Chain plate The fitting used to attach stays to the hull.
Chine - A line, running along the side of the boat, where the bottom forms an angle to the side. Not found on round-bottom boats.
Chainplates - metal plates bolted to the boat which standing rigging is attached to
Chichester -- Sir Francis Chichester, the great English sailor who authored the terrific books
Alone Across the Atlantic and Gypsy Moth
Chock - a guide for an anchor, mooring or docking line, attached to the deck
chocks -- a heavy metal fitting fixed to the deck of a ship through which a line for mooring, towing, or anchor rode is passed
ciguatera -- a severe type of food poisoning caused by eating contaminated fish
clear the decks -- remove unnecessary things from the decks
Cleat - a a two-horned fitting used to secure a line to the boat or mast
clew -- the lower aft corner of the fore and aft sails
Close hauled - a point of sail where the boat is sailing as close to the wind as possible
Close reach - a point of sail where the boat is sailing towards the wind but is not close hauled
Close-Hauled: See Beating
clove hitch -- two half hitches
Coach roof Also trunk. The cabin roof, raised above the deck to provide headroom in the cabin.
coaming -- the raised border around the cockpit, or a hatch to keep out water.
Cockpit - the area, below deck level, that is somewhat more protected than the open deck, from which the tiller or wheel is handled
Companionway The main entrance to the cabin, usually including the steps down into the cabin.
Compound sheer, curving up at the front of the boat and down at the stern, and straight sheer are uncommon.
Counter At the stern of the boat, that portion of the hull emerging from below the water, and extending to the transom. Apr to be long in older designs, and short in more recent boats.
course -- compass heading or the angle of the boat in sailing against the wind
Covering: a tactical manoeuvre in which the lead boat stays between the trailing boat and the wind or the next mark.
crabbing -- going sideways due to set (also catching crabs!)
Cunningham A mainsail control device, using a line to pull down the mainsail a short distance from the luff to the tack. Flattens the sail.
Cunningham: A control line that tensions the forward edge (luff) of a sail.
Cutter Rig:A sail plan with two headsails, a main jib and a smaller staysail set between the jib and the mast.

D signal -- safety signal, "Keep clear of me. I am maneuvering with difficulty."
Daggerboard A board dropped vertically through the hull to prevent leeway. May be completely removed for beaching or for sailing downwind.
Daggerboard: Similar to the centerboard, except it is raised and lowered vertically rather than pivoted.
deadhead -- a floating log
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.
deck plate -- a metal plate fitting on the deck that can be opened to take on fuel or water
dinghy -- a small open boat, usually carried aboard a yacht for going ashore
Displacement - the weight of the water displaced by the boat
Dock - the area a boat rests in when attached to a pier, also the act of taking the boat to the pier to secure it
Dodger A screen, usually fabric, erected to protect the cockpit from spray and wind.
dorado -- a dolphinfish (misnomer), same as mahi mahi
double ender -- boat with a pointed bow and stern
Downhaul: A control line that adjusts and tensions the luff of a sail.
Downwind: (Run, With the Wind) Sailing away from the wind source with the sails let out all the way.
DR -- dead reckoning, deduced reckoning; your position based on speed, direction, and time
Draft - the depth of the boat at its lowest point, also the depth or fullness of the sail
Drift - the leeway, or movement of the boat, when not under power, or when being pushed sideways while under power

Ease - to loosen or let out
ebb -- tide passing from high to low, with the current going out to sea
El Nino -- a warm inshore current annually flowing south along the coast of Ecuador. About every seven to ten years it extends down the coast of Peru , where it has a devastating effect.

Fairlead A fitting used to alter the direction of a working line, such as a bullseye, turning block, or anchor chock.
fall off -- to pay off to leeward or away from the wind
Fall Off: See Head Down.
fathom -- nautical measurement equivalent to a depth of six feet
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.
fiddle -- strip around a table to prevent items from falling off when the boat is at a heel
fishhook -- slang sailing expression for a piece of metal or shroud that cuts or stabs you, the injury usually not discovered until later
fix -- the determined boat's position
flood -- incoming tidal current
flotsam -- floating items of a ship or its cargo at sea, floating debris
fluke -- the digging end of the anchor; also wind irregularity
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 For a triangular sail, the bottom edge.
Force 8 -- gale force wind on the Beaufort Wind Scale
foredeck -- the forward part of a boat's main deck
Foremast - the forward mast of a boat with more that one mast
Forepeak The compartment farthest forward in the bow of the boat. Often used for anchor or sail stowage.
foresail -- forward sail
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 The triangle formed by the forestay, mast, and fore deck.
Forward - toward the bow to the boat
fouled -- entangled or clogged, caught or twisted up
Fractional rig - A design in which the forestay does not go to the very top of the mast, but instead to a point 3/4~ 7s, etc., of the way up the mast.
Freeboard: The distance between the deck and the waterline. Most often it will vary along the length of the boat.
Furl - to fold or roll a sail and secure it to its main support

Gaff - A spar used to support the top of a mainsail - OR

a pole with a hook end used for hauling fish onboard.
Genoa -- also known as genny, usually the biggest jib on the boat
150 percent genoa For rating purposes, the length of a line drawn perpendicular to the luff and intersecting the clew is divided by the length of the base of the Foretriangle. For instance, if the former is 30 feet and the latter 20 feet, the genoa is 150%

Gimball - a device that suspends a compass so that it remains level
GMT -- Greenwich Meridian Time, also known as Universal Time
going to weather -- to sail against the prevailing wind and seas
gooseneck -- fitting that secures the boom to the mast
GPS -- global positioning system; uses satellites in fixed orbits
Great Circle -- a course plotted on the surface of the globe that is the shortest distance between two points
ground tackle -- anchor and anchor gear
gunnels -- also gunwhale; the boat railing
Gunwale - the railing of the boat at deck level
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.

halyard -- also halliard; the cordage used to haul the head of a sail up the mast
hanks -- metal hooks used to secure a sail to a stay; to hank on a sail is to hook it on a stay using the hanks
Hard Alee - the command given to inform the crew that the helm is being turned quickly to leeward, turning the boat windward
hard over -- turning the wheel as far as possible
harden up -- to steer closer to the wind, usually by pulling in on the sheets
hatch -- opening on deck with a cover
haul around -- change from a run to a reach
head -- currently the bathroom aboard a boat
head (of a sail) -- upper corner of a sail
Head Down (Fall Off): To turn the boat away from the wind.
Head For a triangular sail, the top corner. Also a marine toilet.
Head to Wind - the bow turned into the wind, sails luffing
Header: A change in wind direction which lets the boat head down.
Headfoil A grooved, streamline rod, often aluminum, fitted over the forestay. The primary purpose is to provide continuous support of the luff of the sail, but it may also help support the forestay.
headsail -- a sail forward of the mast
Headstay - a wire support line from the mast to the bow
Head-to-Wind: When the bow of a boat is pointing directly into the wind.
Headway - forward motion
Heave To - to stop a boat and maintain position (with some leeway) by balancing rudder and sail to prevent forward movement, a boat stopped this way is "hove to"
heaves -- upward displacing swells
Heel - the leeward lean of the boat caused by the winds action on the sails
Helm - the tiller or wheel, and surrounding area
Helmsman - the member of the crew responsible for steering
Hike - leaning out over the side of the boat to balance it
hike out -- climb to windward
Hiking stick An extension of the tiller that enables the helms man to sir at a distance from it.
Hiking: When a sailor leans over the side of a boat to counteract heel.
Hoist - to raise aloft
hook -- slang term for anchor
hove to - see heave to
hull speed -- the fastest a keelboat will go, usually dependent on length of the hull at the waterline

In Irons - having turned onto the wind or lost the wind, stuck and unable to make headway
Inspection port A watertight covering, usually small, that may be removed so the interior of the hull can be inspected or water removed.
inverter -- electrical power converter; converts square-wave DC current to sine-wave AC current
IOR International Offshore Rating
iron spinnaker -- auxiliary engine

jack line -- a line run for safety purposes from the cockpit forward to the bow of the boat, inside the rail. Clipping on to the jack line with the lanyard of our safety harnesses we were able to minimize being lost overboard when going forward to crew in severe
Jack-Tar -- a sailor from the clipper ship days, so named because they would tar their hair to prevent infection and make it easy to cut
jetsam -- debris, jettisoned items, floating at sea
jib -- a foresail. On a cutter this is the forward most sail, as opposed to staysail located between the jib and the main
jibe -- also gybe; Changing from one tack to the other when sailing downwind.
Jiffy reefing A fast method of reefing. Lines pull down the luff and the leech of the sail, reducing its area.
jig -- fishing technique of lowering a weighted lure until just above the bottom, then alternately jerking the rod upwards and lowering
Jumper stay A short stay supporting the top forward portion of the mast. The stay runs from the top of the mast forward over a short jumper strut, then down to the mast, usually at the level of the spreaders.

kapu -- also tapu (Tahitian); to be taboo. In Polynesian society, in addition to forbidden locations there were also various culture
Keel: The fixed underwater fin on the hull which helps provide stability and prevents the boat from slipping sideways.
Keelson A structural member above and parallel to the keel. Kick-up Describes a rudder or centerboard that rotates back and up when an obstacle is encountered. Useful when a boat is to be beached.
Ketch - a two-masted ship with a small mast mounted forward of the rudder post
knot -- a nautical mile (equivalent to 1.15 miles or 1.852km). Also, any of various tangles of line formed by methodically passing the
Knot - a unit of speed, one knot = 6,076 feet per hour

landfall -- first sight of land
Lanyard - a line attached to any small object for the purpose of securing the object
Lapper A foresail which extends back of and overlapping the mast, such as a 110% genoa jib.
latitude -- an angular measurement or distance measured in degrees, north or south from the equator which is 0 .
Lazarette A stowage compartment at the stern.
Lazy jack: Light lines from the topping lift to the boom, forming a cradle into which the mainsail may be lowered.
Lead refers to the direction in which a line goes. A boom yang, for example, may "lead to the cockpit."
lee -- the side away from the direction of the wind, also used in context to refer to a sheltered place out of the wind, as in the lee of the island
Lee boards Pivoting boards on either side of a boat which serve the same function as a centerboard. The board to leeward is dropped, the board to windward is kept up.
lee cloths -- a cloth hung on the lee side of a berth (the down side when the boat has heel to it) to keep one from rolling out of their
lee shore -- a shore that wind blows onto; it is best to stay well off a lee shore in a storm
Leech - the back edge of a sail
Leech line A line running through the leech of the sail, used to tighten it.
Leeward - downwind or away from the wind.
Lifeline - a cable fence that surrounds the deck to assist in the prevention of crew falling overboard
Lift: A change in wind direction which lets the boat head up.
Line: A rope used for a function on a boat, such as a sheet halyard, cunningham or painter.
list -- inclination of a boat due to excess weight on one side or the other
List - the leaning of a boat to the side because of excess weight on that side
longitude -- distance in degrees east or west of Greenwich, England, meridian which is 0 .
Loose-footed Describes a mainsail attached to the boom at the tack and clew, but not along the foot.
Luff: The forward edge of a sail, or - to stall or flap the sail at its forward edge, or over the entire sail.

mahi mahi -- a powerful fish with a large head, found in tropical and subtropical waters
Mainsail (Main): The sail which is attached to the mast and boom.
Mainsheet - the line that controls the boom
marlinespike -- a pointed metal tool for separating the strands of a rope in splicing
Mast step Fitting or construction into which the base of the mast is placed.
Mast: A spar placed vertically in a boat to hold up the sails.
Masthead rig A design in which the forestay runs to the peak of the mast.
meat hook -- slang expression for a large fishing hook
Mechanical advantage (or purchase) A mechanical method of increasing an applied force. Disregarding the effects of friction, if a force of 100 pounds applied to a tackle is magnified to a force of 400 pounds, the purchase or mechanical advantage is said to be four to one, or 4: 1.
midships -- the middle of the boat
Mizzen - the shorter mast behind the main mast on a ketch or yawl - or - A fore and aft sail flown on the mizzenmast.
mooring -- a float providing a tie off for a boat, usually set to a permanent anchor
Mooring - an anchor or weight, permanently attached to the sea floor, with a buoy going to the surface, used to hold the boat in a certain area
motor-sailing -- sailing with the motor on and in gear
motu--(Hawaiian); small island usually at the reef

Nautical Mile: Measure of length at sea (2025 yards). 1 mile = 1,760 yards.
Nun - a kind of navigational buoy

Off the Wind: Any of the points of sail, except sailing upwind.
offing -- seaward, a safe distance from shore
old salt -- a very experienced and/or old sailor
onboard -- on the boat
orcas -- killer whales
Outhaul Usually a line or tackle, an outhaul is used to pull the clew of the mainsail towards the end of the boom, thus tightening the foot of the sail.

P flag -- signal flag known as the "Blue Peter" [blue square in a white the vessel is about to proceed to sea."
pahua -- giant clam found in tropical waters
Painter - a line tied to the bow of a small boat for the purpose of securing it to a dock or to the shore
pareau -- (traditional Polynesian one-piece wrap); also lava lava [Samoan and Hawaiian];
part -- fray or break
Paul Gaugin -- French painter known for his Marquesan and Tahitian works after 1891
pay out -- to slacken on a line
Pedestal A vertical post in the cockpit used to elevate the steering wheel into a convenient position.
Pennant - a triangular flag
phosphorescence -- luminescence
Pinch - to sail as close as possible towards the wind
Pinching: See Feathering.
pitch -- plunging of a vessel fore and aft
plumeria -- a fragrant blossoming tree found in the tropics and subtropics
Point - to turn closer towards the wind (point up)
Points of Sail: The headings of a sailboat in relation to the wind, i.e., upwind, close reach, reach, broad reach, downwind.
Polaris -- the North Star, the star that is located over the north pole and is the center of revolution for the Earth
pooped -- having a wave wash over the stern of the boat
port -- the left side of the boat; also a harbour
Port tack - sailing with the wind coming from the port side, with the boom on the starboard side
Port: The left side of a boat (when looking forward).
preventer -- line and tackle which limits the movement of the boom, usually for the purpose of preventing accidents by preventing being swept overboard in severe conditions
Privileged vessel - the ship with the right of way
pull -- in rowing, to row an oar, putting your back into it
Pulpit A metal framework on deck at the bow or stern. Provides a safety railing and serves as an attachment for the lifelines.
Pushpit Colloquial, a pulpit located on the stern.
put in -- to enter a port or harbor

Q flag -- all yellow signal flag meaning "My vessel is healthy and I request free pratique."
quarter -- the side of a boat aft of beam and forward of the stern
quay -- wharf used to discharge cargo

rail -- top of the bulwarks on the edge of the deck
Rake The fore or aft angle of the mast. Can be deliberately induced (by adjustment of the standing rigging) to flatten sails, balance steering, etc. Normally slightly aft.
Reach: Sailing with the wind coming over the side, or abeam.
reaching -- sailing a course that is neither close hauled or downwind
Ready about - Instruction to crew to prepare to come about
Reef - to reduce the size of a sail
reef -- to shorten sail, usually by partially lowering it and tying it off with reefing lines
Reef points: A horizontal line of light lines on a sail which may be tied to the boom, reducing the area of the sail during heavy winds.
Reef: To reduce the area of a sail.
Reverse sheer curves down towards the bow and stern.
Rhumb line - a straight line compass course between two points
rigging -- standing rigging refers to shrouds and stays, while running rigging refers to halyards and sheets that control the sails
rode - the line or chain attached to the anchor
Rigging - the standing rigging is the mast and support lines, running rigging is the lines with which you adjust the sails
Right-of-Way: A right-of-way boat has precedence over others on conflicting courses and has the right to maintain its course.
rip current -- as in tide rip; water disturbance created by conflicting current and wind
Roach The curved portion of a sail extending past a straight line drawn between two corners. In a mainsail, the roach extends past the line of the leech between the head and the clew and is often supported by battens.
Rocker The upward curvature of the keel towards the bow and stern.
Rode - the line and chain that connect the anchor to the boat
roller - a wave
Roller reefing: Reduces the area of a sail by rolling it around a stay, the mast, or the boom. Most common on headsails.
rolling heap -- slang expression meaning ocean
Rub-rail: Also rubbing strake or rub strake. An applied or thickened member at the rail, running the length of the boat; serves to protect the hull when alongside a pier or another boat.
rudder -- hinged plate hinged to the stern of the vessel used to steer the boat by turning the wheel
Run (Downwind, With the Wind): Sailing away from the wind source with the sails let out all the way.
running -- going with the wind, downwind sailing (to run downwind)
running backs -- running backstays; temporary backstays used to stabilize the mast and prevent undue flexing in the pumping action
Running backstay: Also runner, or preventive backstay. A stay that supports the mast from aft, usually from the quarter rather than the stern. When the boat is sailing downwind, the runner on the leeward side of the mainsail must be released so as not to interfere with the sail.
Running Rigging: The lines and associated fittings used to adjust and trim the sails, such as halyards, sheets, outhaul, downhaul, cunningham or boom vang.

Running: sailing downwind with the wind coming over the stern of the boat.

safety harness -- a harness, usually made of webbing, worn over the shoulders and around the chest equipped with a lanyard for
Sail Trim (Set): The positioning and shape of the sails to the wind.
salon -- also saloon; main social cabin of a boat
sampan -- a small boat with a narrow design, originally found in Japan and China
samson post -- also sampson post;
Sandwich construction Layered materials such as FRP-foamFRP. Usually adhesively bonded. Typically strong and light. Often used in hulls; very widely used in decks.
SAT NAV -- satellite navigation unit; uses satellites in moving orbits

scope -- the length or extent of anchor rode
scopolamine -- a drug prescribed for motion sickness
Scull - moving the rudder back and forth in an attempt to move the boat forward
sculling oar -- a large oar used for propelling a boat by moving from side to side; also used for an emergency rudder
Scupper Drain in cockpit, Coaming, or toe-rail allowing water to drain out and overboard.
scuppers -- overboard drain holes on deck
Scuttle A round window in the side or deck of a boat that may be opened to admit light and air, and closed tightly when required.
Seat locker A storage locker located under a cockpit seat.
seized - bound together
Self-bailing cockpit A watertight cockpit with scuppers, drains, or bailers that remove water.
Self-tacking Normally applied to a sail that requires no adjustment other than sheeting when the boat is tacked.
self-tending -- tacks itself
set -- the direction of the tide or current, the leeway course of the boat
shackle -- a metal link which can be open and closed for joining chain to anchor, etc.
Shackle: A U-shaped fitting closed with a pin and used to secure sails to lines or fittings, and lines to fittings.
Shake out - to release a reefed sail and hoist the sail aloft
Sheave - the wheel of a block pulley
Sheer strake The topmost planking in the sides, often thicker than other planking.
Sheer The line of the upper deck when viewed from the side. Normal sheer curves up towards the bow and stern,
Sheet: a rope attached to the corner of the sail used for trimming sails for different wind directions.
ship in seas -- take in seas
shroud -- a wire used to stay or hold a mast in position to which the sails may also be hanked
single sideband -- a type of modulation applied to radio signals used to improve transmission power and reception signal to noise ratio.
Skeg: For sailboats, usually refers to a structural support to which the rudder is fastened.
skipjack -- bonito, aku; a type of tuna
Slab reefing Also points reefing, and sometimes jiffy reefing. Reduces the area of the mainsail by partially lowering the sail and resecuring the new foot by tying it to the boom with points, or light lines attached to the sail.
slats -- battens
slatting -- flapping
sloop -- A boat with a sailplan comprisimg a jib headsail and a mainsail.
snubber -- a spring line tied from the boat to chain rode, usually near the water's surface. It helps disperse tension forces. It also prevents damage to the boat by ground tackle and can help in the retrieval of the ground tackle in heavy weather. (to reduce the snap of the rode when it stretched out)
soggering -- being lazy and unassuming of responsibility
Sole The floor of the cockpit or cabin.
sounding -- diving
sou'wester -- a wind coming from the southwest
Spar Poles, most often of wood, aluminum or carbon fiber, used as supports, such as the mast, boom, or spinnaker pole.
Spar: A wooden or metal pole used to support a sail, such as a mast or boom.
Spinnaker A large, triangular sail, most often symmetrical, flown from the mast in front of all other sails and the forestay. Used sailing downwind.
Spirit The spar that supports the peak of a spritsail. Splashboard A raised portion of the hull forward of the cockpit intended to prevent water entering.
Spreaders: Also crosstrees. Short horizontal struts extending from the mast to the sides of the boat, changing the upward angle of the shrouds.
spring line a line tied between two opposing forces that has a neutralizing effect on the force vectors, such as those creating by surge. At the dock with a bow line and stern line tied off, a spring line is often added to limit the working movements of a floating boat.
sprit -- a spar that extends the bow of the boat
Spritsail A four-sided fore and aft sail set on the mast, and supported by a spar from the mast diagonally to the peak of the sail.
Standing rigging Permanent rigging used to support the spars. May be adjusted during racing, in some classes.
starboard-- right; on the right side of the boat
Starboard tack - a course with the wind coming from starboard and the boom on the port side
Starboard: The right side of a boat (when looking forward).
Staysail A sail that is set on a stay, and not on a yard or a mast.
Stem The most forward structural member in the bow.
Step - the frame that the bottom of the mast ends into
Stern: The back end of a boat.
stores -- provisions stored onboard
Stow - to put away or to store onboard
Strake: On wooden boats, a line of planking running from the bow to the stern along the hull.
studding out a sail-- extending a sail using a whisker pole
sump pump-- small pump for shower drainage
surge -- rising and falling of the sea, usually due to wave action

Tabernacle A hinged mast step located on deck. Since it is hinged, the mast may be lowered easily.
Tack - the front, lower corner of the sail, also course with the wind coming from the side of the boat, also to change course by turning into the wind so that the wind comes from the other side of the boat
Tacking: turning the boat so that the bow passes through the wind.
taffrail log-- Walker log; a propeller drawn through the water that operates an odometer on the boat registering the distance sailed
Taffrail The rail at the stern of the boat.
Tang A fitting, often of sheet metal, used to attach standing rigging to a spar, or to the hull.
Telltales: Short pieces of yarn, ribbon, thread, or tape attached to the sail which are used to show the air flow over the sail; or when attached to the shroud indicate apparent wind direction.
Tender - a small boat used to transport crew and equipment from shore to a larger boat
the hard -- land
Thwart A transverse structural member in the cockpit. In small boats, often used as a seat.
Tiller: The stick or tube attached to the top of a rudder and used to turn it.
Toe-rail A low rail, often slotted, along the side of the boat. Slots allow drainage and the attachment of blocks.
tonnage -- the weight, in tons, of a boat.
Topping lift - a line that holds up the boom when it is not being used, also the line that controls the height of a spinnaker pole
torch -- old sailing term for lantern that throws out a beam of light. Now it also can refer to a flashlight.
trailing -- dragging, as in "dragging a line"
Trampoline The fabric support that serves for searing between the hulls of a catamaran.
Transom The flat, or sometimes curved terminating structure of the hull at the stern of a boat.
Trapeze Wire gear enabling a crewmember to place all of his weight outboard of the hull, thus helping to keep the boat level.
Traveler A fitting across the boat to which sheets are led. In many boats the traveler may be adjusted from side to side so that the angle of the sheets can be changed to suit conditions.
Trim - to adjust the sails, also the position of the sails
trimaran-- a boat with three hulls
True Wind: The actual speed and direction of the wind felt when standing still.
Tuning - the adjustment of the standing rigging, the sails and the hull to balance the boat for optimum performance
Turnbuckle: A fitting used to adjust the length and tension of a shroud or forestay.
Turning mark: a buoy on the race course around which boats must turn.
Turtling: A capsize position with the boat turned upside down with the mast pointing down to the sea bottom.
Twing Similar to a Barber hauler, a twing adjusts the angle of sheeting.

underway -- moving under power of sail or motor
Upwind: toward the wind (see beating).

Vang: A control line, usually a multi-purchase tackle, secured to the boom to prevent it from lifting.
V-berth-- usually the forward berth of the boat, located in the bow
Ventilator Construction designed to lead air below decks. May have a cowl, which can be angled into or away from the wind; and may be constructed with baffles, so that water is not allowed below, as in Dorade ventilator.
VHF -- very high frequency radio
victuals -- food
vittles-- victuals

Wake - the swell caused by a boat passing through water
Warp Heavier lines (rope or wire) used for mooring, anchoring and towing. May also be used to indicate moving (warping) a boat into position by pulling on a warp.
watch - working shift
Weather Helm: The natural tendency of a sailboat to turn toward the wind, which the helmsman feels as the tiller tries to turn to leeward.
whip -- rope rove
Whisker pole A short spar, normally kept stowed, which may be used to push the clew of a jib away from the boat when the boat is running downwind.
winch -- mechanical device for hauling in a line
wind rose -- a diagram usually shown on pilot charts that indicates the frequency and intensity of wind from different directions for a particular place
windlass -- winch for hauling in the anchor chain or line
Window A transparent portion of a jib or mainsail.
Windward - upwind
Wing and Wing: Sailing directly downwind with the jib and mainsail set on opposite sides of the boat to capture more wind.
Wishbone A boom composed of two separate curved pieces, one on either side of the sail. With this rig, sails are usually self tending and loose-footed.

yaw, yawing -- to turn from side to side in an uneven course

zincs -- zinc plates attached to the hull to minimize electrolysis (and ultimate failure) of the metal in the rudder and other areas