Parts of a Boat

A raised rim around a hatch opening that limits water entry and supports the hatch cover. Its height, strength and sealing surface contribute to the opening’s weathertight or watertight integrity. Drains, gaskets, dogs and the coaming itself must be kept clean and undamaged.

A lever, screw or cam fitting used to clamp a hatch cover tightly against its seal. Dogs are secured in the correct sequence and tension so the gasket compresses evenly. Missing, seized or overtightened dogs can compromise closure integrity or damage the cover and seal.

The position and route by which a headsail sheet is led to its block, fairlead or car. Moving the lead forward generally increases leech tension relative to foot tension, while moving it aft does the reverse. The optimum position varies with reefing, sail shape and point of sail.

A sail batten extending from the leech to or close to the luff. It supports the sail’s shape over a larger area than a short leech batten and can reduce flogging. Cars, pockets and compression loads require suitable design, and the battens can make hoisting, reefing or furling more demanding.

A mast whose heel is supported on the deck rather than continuing through it to a step below. Compression loads are transferred through the deck structure and usually a supporting post or bulkhead to the hull. Standing rigging becomes especially important to stability if the mast heel is not positively retained.

Lift produced by fluid flow around a moving foil, hull or planing surface. It increases with speed, fluid density, area and lift coefficient and can support part or all of a craft’s weight. Hydrofoils and planing hulls rely on dynamic lift, unlike static buoyancy, which exists without forward motion.

A stern form in which the upper part projects aft beyond the waterline and rises from a curved afterbody. It was common on traditional sailing yachts and ships and can provide a graceful overhang and increased deck length. The shape differs from a flat transom stern and affects usable volume and behaviour when pitching.

Repeated variation of load on a component over time. Even loads below the material’s ultimate strength can initiate fatigue cracks, loosen fittings or damage fibres after many cycles. Rigging, shafts, moorings and hull structures therefore require inspection based on both load magnitude and service history.

An adjustable stay used to support a mast locally and control bend or forestay tension. Checkstays commonly lead aft from the mast and may need easing on the leeward side during a tack or gybe. Incorrect use can distort the mast or conflict with the mainsail, so operation depends on the particular rig design.

A raised border around a cockpit that helps keep water out and provides structural and crew support. Its shape can deflect spray, support seating and form the edge for lockers or cockpit enclosures. Openings and fittings through the coaming should preserve drainage, strength and weather protection.