← The Encyclopedia of Sails
Part 10 — Reference
Glossary of sailing terms
Every term used in the encyclopedia, defined in plain language. Terms with a full entry link through to their own page.
No term matches that. Try “luff”, “clew” or “telltale” — or read the encyclopedia’s 28 chapters.
- Afterguy — full entry
- The spinnaker sheet that goes through the jaw of the spinnaker pole. Used on big boats where separate sheet and afterguy attach to both spinnaker clews. Heavier than regular sheets due to increased pressure.
- Aft — full entry
- Toward the rear of the boat
- Anchor — full entry
- Device used to secure a boat to the seabed
- Apparent wind — full entry
- The wind experienced by a moving boat
- Aspect ratio — full entry
- The height of a foil (sail, keel, or rudder) divided by its width. High aspect sails have long luffs and short feet.
- Backstay — full entry
- Wire supporting the mast from the stern
- Barometer — full entry
- Air pressure gauge
- Batten — full entry
- Flexible strip inserted into sail to maintain shape
- Beam — full entry
- Width of a boat at its widest point
- Bearing — full entry
- Direction to object
- Beaufort scale — full entry
- Wind force scale
- Becket — full entry
- Loop of rope or eye splice
- Berth — full entry
- Sleeping area or docking space
- Bias Elongation — full entry
- See Warp
- Bight — full entry
- Curve or bend in a rope
- Bilge — full entry
- Lowest inner part of a boat’s hull
- Bi-Radial — full entry
- A sail construction technique where radial panels emanate from the head and clew
- Block — full entry
- Pulley used in sailing
- Boom — full entry
- Spar at bottom of mainsail
- Boomvang — full entry
- A block-and-tackle or hydraulic ram controlling boom angle. Lowering the boom tightens the mainsail leech
- Bow — full entry
- Front of the boat
- Bowline — full entry
- Essential knot used in sailing
- Bowsprit — full entry
- Spar extending from bow
- Broach — full entry
- Accidental turning into the wind
- Camber — full entry
- Curve of a sail
- Capsize — full entry
- To overturn
- Catamaran — full entry
- Double-hulled vessel
- Centerboard — full entry
- Retractable keel
- Chainplate — full entry
- Metal plates securing rigging to hull
- Chafe — full entry
- Wear from friction
- Chart — full entry
- Marine map
- Cleat — full entry
- Fitting for securing lines
- Clew — full entry
- Lower aft corner of a sail. Outhaul attaches here on mainsails; sheets attach here on genoas
- Close-hauled — full entry
- Sailing almost directly into the wind
- Companionway — full entry
- Entrance to cabin
- Compass — full entry
- Navigation instrument
- Course — full entry
- Intended direction
- Cross cut — full entry
- A sail construction technique where panels are parallel to each other and perpendicular to the sail’s leech
- Cruising — full entry
- Recreational sailing
- Cunningham — full entry
- Named after Briggs Cunningham, a control that adjusts draft position by changing sail luff tension
- Dead reckoning — full entry
- Position estimate
- Deck — full entry
- Upper surface of boat
- Depression — full entry
- Low pressure area
- Deviation — full entry
- Compass error
- Downwind Sails
- Draft — full entry
- 1. The deepest part of the curve in a sail. 2. The distance from the waterline to the bottom of a boat’s keel
- Drift — full entry
- Movement caused by wind/current
- Drogue — full entry
- Sea anchor
- E — full entry
- The distance from the aft face of the mast to the outermost point on the boom where the mainsail is pulled
- Ease — full entry
- To loosen a line
- Eye splice — full entry
- Permanent loop in rope end
- Eyelet — full entry
- Reinforced hole in sail
- Fairlead — full entry
- Fitting guiding a line
- Fall off — full entry
- Turn away from wind
- Fathom — full entry
- Unit of depth (6 feet)
- Fender — full entry
- Cushion protecting hull
- Fetch — full entry
- Wind-water distance
- Fictitious luff — full entry
- Imaginary line for sail design
- Fill Threads — full entry
- See Warp
- Fix — full entry
- Position determination
- Flattening Reef — full entry
- A sail control that flattens the mainsail’s bottom part using a grommet on the leech about a foot above the boom. Also called “flattener”
- Foot — full entry
- Bottom edge of a sail
- Foreguy — full entry
- Line pulling the outboard end of the spinnaker pole down
- Forestay — full entry
- Wire supporting mast from bow
- Foretriangle — full entry
- Triangle formed by the forestay, forward edge of mast and foredeck
- Foredeck — full entry
- Forward part of deck
- Front — full entry
- Weather system boundary
- Furling — full entry
- Rolling up a sail
- Gaff — full entry
- Spar supporting sail top
- Gale — full entry
- Strong wind
- Genoa — full entry
- Large headsail
- Gooseneck — full entry
- Boom attachment to mast
- Gore — full entry
- Vertical panel in sail
- Gradient — full entry
- Pressure difference
- Grommets — full entry
- Metal rings in sail
- Gunwale — full entry
- Upper edge of boat’s side
- Gybe — full entry
- Change course with wind aft
- Halyard — full entry
- Line for raising sails
- Hand — full entry
- To furl or take in sail
- Head — full entry
- Top corner of a sail
- Heading — full entry
- Direction boat points or current direction
- Headstay — full entry
- Forestay
- Headstay Sag — full entry
- Deflection of the headstay to leeward and aft caused by wind force on the sail
- Head up — full entry
- Turn toward wind
- Headsail — full entry
- Any sail forward of mast
- Heel — full entry
- Boat’s lateral incline
- Helm — full entry
- Steering control
- Hull — full entry
- Main body of boat
- I — full entry
- Measurement of foretriangle height, with specific measuring points varying by rating rule
- Irons — full entry
- In stays, head to wind
- Isobar — full entry
- Equal pressure line
- J — full entry
- Measurement of foretriangle base – distance between mast and forestay
- Jib — full entry
- Forward triangular sail
- Jib Lead — full entry
- Block or fairlead for jib sheet between clew and winch, affecting jib shape
- Jibing — full entry
- Same as gybing
- Jury rig — full entry
- Temporary repair
- Keel — full entry
- Fixed underwater fin
- Kevlar — full entry
- Sail fabric material
- Knot — full entry
- Speed measurement (1 nautical mile/hour)
- Knots — full entry
- Wind speed measure
- Laminate — full entry
- Multi-layer sail material
- Laminated Sail Cloth — full entry
- Multi-layer fabric with fiber and film bonded by adhesive, using film for bias stretch control and fiber for oriented direction stretch resistance
- Lanyard — full entry
- Short line for securing items
- Latitude — full entry
- North-south position
- Lazy Guy/Lazy Sheet — full entry
- Lines used on large boats for jibing spinnaker, attached to inactive clew
- Lazyjacks — full entry
- Lines supporting lowered sail
- Leach — full entry
- Aft edge of sail
- Lee — full entry
- Side sheltered from wind
- Lee Helm — full entry
- Boat’s tendency to bear off when helm is released, common in light air or with forward-positioned mast
- Leeward — full entry
- Away from wind
- Life jacket — full entry
- PFD (personal flotation device)
- Lifeline — full entry
- Safety wire around deck
- Lines — full entry
- Ropes used on boats
- Log — full entry
- Speed/distance record
- Longitude — full entry
- East-west position
- LP — full entry
- Luff Perpendicular – shortest distance from genoa clew to luff, used to express genoa size as percentage
- Luff — full entry
- 1. Forward edge of a sail. 2. Sail flapping from heading too close to wind or insufficient trim. 3. Altering course toward wind
- Luffing — full entry
- Fluttering of sail
- Mainsail — full entry
- Principal sail
- Mainsheet — full entry
- Line controlling mainsail
- Mast — full entry
- Vertical spar supporting sails
- Mooring — full entry
- Permanent anchoring spot
- Mylar — full entry
- Sail material
- Nautical mile — full entry
- 6,076 feet
- Navigation — full entry
- Determining position/course
- Noon sight — full entry
- Sun observation at midday
- Outhaul — full entry
- Control line pulling mainsail clew to boom end
- Overboard — full entry
- Off the boat
- Overlap — full entry
- Sail extending past mast
- Overpowered/Underpowered — full entry
- Describes when a boat has too much sail (heeling too much) or too little sail (causing slowdown)
- P — full entry
- Measurement from boom top at gooseneck to highest point of mainsail on mast
- Painter — full entry
- Bow line
- Peak — full entry
- Upper corner of sail
- Pennant — full entry
- Small flag
- Piloting — full entry
- Coastal navigation
- Pinch — full entry
- Sail too close to wind
- Plot — full entry
- Mark position
- Port — full entry
- Left side of boat
- Port tack — full entry
- Wind from port side
- Quarter — full entry
- Aft section of side
- Rake — full entry
- Mast’s inclination from vertical, measured from mast back at partners to main halyard plumb line
- Range — full entry
- Navigation markers
- Reach — full entry
- Sailing across wind
- Reacher — full entry
- High-clewed genoa for heavy wind reaching, also called “blast reacher”
- Reef — full entry
- Reduce sail area
- Rigging — full entry
- Boat’s line/wire system
- Roach — full entry
- Curved sail section beyond straight line from head to clew
- Rudder — full entry
- Steering blade
- Running — full entry
- Sailing away from wind
- Sail plan — full entry
- Arrangement of sails
- Sailcloth — full entry
- Sail material
- Schooner — full entry
- Two-masted vessel
- Scrim — full entry
- Reinforcement layer
- Scrim Cloth — full entry
- Extremely loose-woven cloth laminated to Mylar for strong, lightweight sailcloth, distinctive for spaces between threads
- Seam — full entry
- Join between sail panels
- Seam allowance — full entry
- Extra material at join
- Sea state — full entry
- Wave condition
- Shape — full entry
- Three-dimensional form
- Sheet — full entry
- Line controlling sail
- Shelf Foot — full entry
- Mainsail option providing extra lower third shaping control via flat cloth connecting sail bottom to boom
- Shrouds — full entry
- Side support wires
- Skeg — full entry
- Rudder support
- Slack — full entry
- Loose, not tight
- Sleeve — full entry
- Mast attachment method
- Sloop — full entry
- Single-masted vessel
- Spinnaker — full entry
- Large downwind sail
- Spreaders — full entry
- Horizontal mast supports
- Squaring the Pole — full entry
- Tightening afterguy to pull spinnaker pole back
- Stanchion — full entry
- Lifeline support
- Starboard — full entry
- Right side of boat
- Stay — full entry
- Support wire for mast
- Stern — full entry
- Rear of boat
- Stretch — full entry
- Fabric elongation
- Swage — full entry
- Metal fitting on wire
- Tack — full entry
- 1. Lower forward corner of sail. 2. Turning boat through wind. 3. Port/starboard designation based on boom position
- Tackle — full entry
- Block and line system
- Tape — full entry
- Reinforcement strip
- Tape-Drive® — full entry
- UK Sailmakers’ patented system using high-strength Kevlar tapes along computer-mapped load lines to maintain sail shape
- Tabling — full entry
- Edge reinforcement
- Telltales — full entry
- Wind indicators
- Tentering — full entry
- Fabric stabilization
- Thimble — full entry
- Protective metal eye
- Thread — full entry
- Sewing material
- Tiller — full entry
- Steering lever
- Topping lift — full entry
- Supports boom
- Track — full entry
- 1. Rail for sail hardware 2. Course made good
- Transit — full entry
- Alignment marks
- Transom — full entry
- Stern cross-section
- Trim — full entry
- Adjust sails
- Triradial — full entry
- Panel arrangement
- True wind — full entry
- Actual wind direction
- Under way — full entry
- Boat in motion
- UV cover — full entry
- Sail protection strip
- Vang — full entry
- Control for boom
- Variation — full entry
- Angle between true north and magnetic north, which differs by location and changes slowly over time
- Wake — full entry
- Trail behind boat
- Warp — full entry
- Length-wise threads in cloth
- Warp, Fill and Bias — full entry
- Terms describing thread directions in woven cloth. Warp threads parallel longest edge, fill threads perpendicular. Bias refers to off-thread stresses
- Warp-Oriented Cloth — full entry
- Sailcloth with greater warp direction strength, sometimes using only warp yarns glued to Mylar film
- Waterline — full entry
- Where hull meets water
- Weave — full entry
- Fabric construction
- Weather helm — full entry
- Tendency to turn windward; measured in rudder angle degrees needed for straight course
- Windage — full entry
- Wind resistance
- Windlass — full entry
- Anchor handling machine
- Windward — full entry
- Toward the wind
- Winch — full entry
- Line handling drum
Still not sure what you need?
Your local loft talks about sails all day. Tell them about your boat and how you sail it, and they will translate the jargon into an inventory.