Afterguy: 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.
Flattening Reef: 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”
Heading: Direction boat points or current direction
Headstay: Forestay
Headstay Sag: Deflection of the headstay to leeward and aft caused by wind force on the sail
Head up: Turn toward wind
Headsail: Any sail forward of mast
Heel: Boat’s lateral incline
Helm: Steering control
Hull: Main body of boat
I
I: Measurement of foretriangle height, with specific measuring points varying by rating rule
Irons: In stays, head to wind
Isobar: Equal pressure line
J
J: Measurement of foretriangle base – distance between mast and forestay
Jib: Forward triangular sail
Jib Lead: Block or fairlead for jib sheet between clew and winch, affecting jib shape
Jibing: Same as gybing
Jury rig: Temporary repair
K
Keel: Fixed underwater fin
Kevlar: Sail fabric material
Knot: Speed measurement (1 nautical mile/hour)
Knots: Wind speed measure
L
Laminate: Multi-layer sail material
Laminated Sail Cloth: Multi-layer fabric with fiber and film bonded by adhesive, using film for bias stretch control and fiber for oriented direction stretch resistance
Lanyard: Short line for securing items
Latitude: North-south position
Lazy Guy/Lazy Sheet: Lines used on large boats for jibing spinnaker, attached to inactive clew
Lazyjacks: Lines supporting lowered sail
Leach: Aft edge of sail
Lee: Side sheltered from wind
Lee Helm: Boat’s tendency to bear off when helm is released, common in light air or with forward-positioned mast
Leeward: Away from wind
Life jacket: PFD (personal flotation device)
Lifeline: Safety wire around deck
Lines: Ropes used on boats
Log: Speed/distance record
Longitude: East-west position
LP: Luff Perpendicular – shortest distance from genoa clew to luff, used to express genoa size as percentage
Luff: 1. Forward edge of a sail. 2. Sail flapping from heading too close to wind or insufficient trim. 3. Altering course toward wind
Luffing: Fluttering of sail
M
Mainsail: Principal sail
Mainsheet: Line controlling mainsail
Mast: Vertical spar supporting sails
Mooring: Permanent anchoring spot
Mylar: Sail material
N
Nautical mile: 6,076 feet
Navigation: Determining position/course
Noon sight: Sun observation at midday
O
Outhaul: Control line pulling mainsail clew to boom end
Overboard: Off the boat
Overlap: Sail extending past mast
Overpowered/Underpowered: Describes when a boat has too much sail (heeling too much) or too little sail (causing slowdown)
P
P: Measurement from boom top at gooseneck to highest point of mainsail on mast
Painter: Bow line
Peak: Upper corner of sail
Pennant: Small flag
Piloting: Coastal navigation
Pinch: Sail too close to wind
Plot: Mark position
Port: Left side of boat
Port tack: Wind from port side
Q
Quarter: Aft section of side
R
Rake: Mast’s inclination from vertical, measured from mast back at partners to main halyard plumb line
Range: Navigation markers
Reach: Sailing across wind
Reacher: High-clewed genoa for heavy wind reaching, also called “blast reacher”
Reef: Reduce sail area
Rigging: Boat’s line/wire system
Roach: Curved sail section beyond straight line from head to clew
Rudder: Steering blade
Running: Sailing away from wind
S
Sail plan: Arrangement of sails
Sailcloth: Sail material
Schooner: Two-masted vessel
Scrim: Reinforcement layer
Scrim Cloth: Extremely loose-woven cloth laminated to Mylar for strong, lightweight sailcloth, distinctive for spaces between threads
Seam: Join between sail panels
Seam allowance: Extra material at join
Sea state: Wave condition
Shape: Three-dimensional form
Sheet: Line controlling sail
Shelf Foot: Mainsail option providing extra lower third shaping control via flat cloth connecting sail bottom to boom
Shrouds: Side support wires
Skeg: Rudder support
Slack: Loose, not tight
Sleeve: Mast attachment method
Sloop: Single-masted vessel
Spinnaker: Large downwind sail
Spreaders: Horizontal mast supports
Squaring the Pole: Tightening afterguy to pull spinnaker pole back
Stanchion: Lifeline support
Starboard: Right side of boat
Stay: Support wire for mast
Stern: Rear of boat
Stretch: Fabric elongation
Swage: Metal fitting on wire
T
Tack: 1. Lower forward corner of sail. 2. Turning boat through wind. 3. Port/starboard designation based on boom position
Tackle: Block and line system
Tape: Reinforcement strip
Tape-Drive®: UK Sailmakers’ patented system using high-strength Kevlar tapes along computer-mapped load lines to maintain sail shape
Tabling: Edge reinforcement
Telltales: Wind indicators
Tentering: Fabric stabilization
Thimble: Protective metal eye
Thread: Sewing material
Tiller: Steering lever
Topping lift: Supports boom
Track: 1. Rail for sail hardware 2. Course made good
Transit: Alignment marks
Transom: Stern cross-section
Trim: Adjust sails
Triradial: Panel arrangement
True wind: Actual wind direction
U
Under way: Boat in motion
UV cover: Sail protection strip
V
Vang: Control for boom
Variation: Magnetic deviation
W
Wake: Trail behind boat
Warp: Length-wise threads in cloth
Warp, Fill and Bias: Terms describing thread directions in woven cloth. Warp threads parallel longest edge, fill threads perpendicular. Bias refers to off-thread stresses
Warp-Oriented Cloth: Sailcloth with greater warp direction strength, sometimes using only warp yarns glued to Mylar film
Waterline: Where hull meets water
Weave: Fabric construction
Weather helm: Tendency to turn windward; measured in rudder angle degrees needed for straight course
