Nautical terms
46 of 469 terms in Hull & deck. Show all
B
- Backing plate Hull & deck
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A reinforcing plate under the deck behind a cleat, winch or other fitting, which spreads the load so bolts cannot pull through.
The Coast Guard handbook says hardware used for towing should always have backing plates and be through-bolted, not screwed.
- Beam Hull & deck
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The boat's width at its widest point.
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- Bilge (Bilges) Hull & deck
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The lowest part of the inside of the hull, below the floorboards, where water collects. The Coast Guard counts clean bilges as part of keeping a boat in good operating condition.
oregon.gov · discoverboating.com · ionianmarinesurveys.com · uscgboating.org
- Bow Hull & deck
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The front end of the boat. Moving toward it is going forward; the front right is the starboard bow and the front left the port bow.
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- Bulkhead Hull & deck
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An upright wall inside the boat dividing compartments. Many are structural, adding strength, and some are watertight.
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- Bulwark Hull & deck
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An extension of the hull side above the deck forming a solid wall around its edge.
C
- Chine (Hard chine, Soft chine) Hull & deck
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Where the bottom of the hull meets the sides. A hard chine is a sharp angle; a soft chine is rounded. Chine shape affects speed and turning.
- Coaming Hull & deck
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A raised rim around a cockpit, hatch or other opening that keeps water on deck from running below.
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- Cockpit Hull & deck
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The recessed open deck area, usually aft, from which the boat is handled or where crew and guests sit. A self-bailing cockpit drains overboard through scuppers.
- Companionway Hull & deck
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The entryway and steps leading from the deck or cockpit down into the cabin.
- Cored hull (Core, Balsa core, Cored deck, Sandwich construction) Hull & deck
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Construction with a lightweight core, commonly end-grain balsa or foam, sandwiched between two fiberglass skins to make a stiff, light deck or hull.
Water leaking in around deck hardware can soak and rot the core, often without visible signs at first; surveyors look for it with moisture meters and hammer sounding.
D
- Deadrise (Deep-V, Modified-V) Hull & deck
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The angle of the V in a hull's bottom, usually measured at the transom of planing powerboats. A deep-V hull has sharp deadrise, typically more than 20 degrees; a modified-V has less than 20; a flat-bottom boat has little or none.
- Displacement Hull & deck
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The weight of a boat, equal to the weight of the water it pushes aside when floating. Light displacement excludes fuel, water, gear and people; loaded displacement includes them.
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- Displacement hull Hull & deck
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A hull that always moves through the water, pushing it aside, rather than climbing on top. Trawlers typically have one. Adding power beyond hull speed takes excessive power for little gain.
- Draft (Draught) Hull & deck
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How deep the boat reaches below the waterline, measured to the lowest point of the keel, or of the propeller, rudder or skeg if they hang lower. It is the least depth of water the boat can float in.
Draft is not fixed: it changes with how the boat is loaded and trimmed.
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F
- Fiberglass (FRP, GRP, Glass-reinforced plastic) Hull & deck
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The material most production boats are built from: glass fibers, woven or chopped, set in resin and laid up in a mold. The structure is built from layers called laminates.
- Fin keel (Full keel, Long keel) Hull & deck
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A sailboat keel shaped like a fish's fin: shorter fore-and-aft and deeper than a full (long) keel, which runs much of the hull's length.
- Flybridge (Flying bridge) Hull & deck
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A raised, second-level helm station on top of a powerboat's cabin, above the main helm, giving the operator a better view.
A flybridge adds height, so check your air draft for bridges.
- Freeboard Hull & deck
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The height of the boat's side above the water, from the waterline up to the deck or gunwale. High freeboard and superstructure give the wind more to push on, which affects handling at low speed.
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G
- Gelcoat (Gel coat) Hull & deck
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The smooth, colored outer layer of resin on a fiberglass boat, applied first in the mold. It gives the shine and some protection, but water can slowly pass through it.
- Gunwale (Gunnel) Hull & deck
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The upper edge of the boat's side, where hull meets deck. Pronounced "gunnel".
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H
- Hatch Hull & deck
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An opening in the deck with a cover, for access, light or ventilation. Deck hatches should seal watertight when closed.
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- Hawsepipe (Hawsehole, Hawse pipe) Hull & deck
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A pipe or opening through the deck or bow through which the anchor rode runs, usually down into the chain or rope locker below.
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- Hull Hull & deck
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The main body of the boat: the outer shell and the structure inside it below the main deck, which together keep the water out and give the boat its strength.
ecfr.gov · higherlogicdownload.s3.amazonaws.com · oregon.gov
- Hull speed (Critical speed) Hull & deck
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The practical top speed of a displacement hull, set by its waterline length: about 1.34 times the square root of the waterline length in feet, in knots. A 36-foot waterline gives about 8 knots.
Pushing a displacement boat past hull speed takes much more power and fuel for very little gain.
K
- Keel Hull & deck
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The backbone running fore and aft along the bottom centerline of the hull. On sailboats the keel also reaches well below the hull to resist sideways drift (leeway).
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L
- Lazarette (Laz) Hull & deck
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A storage compartment in the stern of the boat.
- Length overall (LOA) Hull & deck
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The boat's length from the foremost to the aftermost point of the hull, measured in a straight line. The Navigation Rules use length overall for all their size limits (12 m, 20 m and so on).
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- Lifelines (Railings, Guardrails) Hull & deck
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The wires or rails around the edge of the deck, supported by stanchions, that help keep people from falling overboard.
P
- Planing hull Hull & deck
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A hull shaped so that, with enough power, it lifts and skims on the surface ("gets on plane"). Once on plane a small increase in power gives a large increase in speed.
The Coast Guard handbook advises bringing power on and off gradually when going on or off plane; a sudden drop off plane stops the boat abruptly.
- Pulpit (Bow pulpit, Stern pulpit) Hull & deck
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A rail structure at the bow, and on many sailboats a matching one at the stern, at the ends of the lifelines.
R
- Rubrail (Rub rail, Rubbing strake) Hull & deck
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A protective strip, often rubber, running around the hull where the deck meets the sides, to take bumps against docks and pilings.
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- Rudder Hull & deck
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The movable vertical blade at the stern, turned by the wheel or tiller, that steers the boat by deflecting water flowing past it.
S
- Scupper (Scuppers) Hull & deck
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A drain opening in the deck, toe rail or bulwark that lets water on deck run overboard. Self-bailing cockpits drain through scuppers.
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- Semi-displacement hull (Semi-planing hull) Hull & deck
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A hull between displacement and planing types, often with soft chines or a rounded bottom, that partly lifts at higher speed but never fully planes.
- Sheer (Sheer line) Hull & deck
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The curve of the deck edge from bow to stern seen from the side. A strong sheer raises the bow, adding buoyancy forward.
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- Skeg Hull & deck
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A fin or extension of the keel aft, ahead of or under the rudder and propeller, that helps the boat track straight and in some boats supports the rudder's lower bearing.
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- Sole (Cabin sole, Cockpit sole) Hull & deck
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The floor of a cabin or cockpit. The cockpit sole is the floor you stand on in the cockpit.
- Stanchion Hull & deck
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An upright post, usually metal, along the deck edge that holds the lifelines or railing.
BoatUS lists re-bedding leaking stanchions and cleats to protect a cored deck from rot among common survey recommendations.
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- Stern Hull & deck
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The back end of the boat. Moving toward it is going aft; the back corners are the port and starboard quarters.
- Stringer (Longitudinal) Hull & deck
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A fore-and-aft structural member inside the hull, running parallel to the keel, that gives the hull strength along its length.
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- Swim platform (Swim step) Hull & deck
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A platform across the transom, usually with a ladder, for boarding from the water or a dinghy.
The Coast Guard warns that carbon monoxide can collect around the swim platform while engines or a generator run; keep people off it then.
T
- Toe rail Hull & deck
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A low rail or raised strip along the edge of the deck that helps you keep your footing. It often has slots or holes for drainage and for attaching blocks and lines.
- Topsides Hull & deck
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The sides of the hull between the waterline and the deck. The word is also used for the area on deck, as in "going topside".
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- Transom Hull & deck
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The flat or slightly curved surface across the stern of a square-sterned boat. The primary HIN is on the starboard side of it, and outboards and swim platforms mount to it.
The Coast Guard handbook notes a wide transom stern gives following seas a large surface to push on.
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W
- Waterline (Boot stripe, Boot top, LWL, Length on waterline) Hull & deck
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The line where the hull meets the water surface, often marked by a painted boot stripe at the designed waterline. Length on the waterline (LWL) is the hull's length measured there.
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General guidance for recreational boaters, researched from the sources listed and written in our own words. Your equipment manuals, local knowledge, the Navigation Rules and a qualified instructor come first.