Maritime & Yachting Glossary

A–D

Aft

Toward the stern (rear) of the vessel.

Beam

The widest point of a vessel's hull, measured perpendicular to the centerline.

Berth

A designated space for a vessel in a marina or port; also, a sleeping accommodation aboard.

Bilge

The lowest internal part of the hull where water collects.

Bollard

A strong post on a dock or vessel used for securing mooring lines.

Bow

The forward part of the vessel.

Bulbous Bow

A protruding bulb below the waterline at the bow, reducing wave-making resistance and improving fuel efficiency.

Bulkhead

An internal wall or partition within the hull, often structural and watertight.

Catamaran

A vessel with two parallel hulls connected by a bridging structure. See catamarans.

Classification Society

An organization (Lloyd's Register, DNV, Bureau Veritas, RINA) that establishes and verifies construction and safety standards for vessels.

Displacement

The weight of water displaced by the hull, equal to the vessel's total weight.

Draft

The vertical distance from the waterline to the deepest point of the hull or keel.

E–L

Fender

A cushioning device hung between the hull and dock to prevent damage during berthing.

Flag State

The nation under whose flag a vessel is registered, determining regulatory jurisdiction.

Flybridge

An open or semi-enclosed upper deck above the main helm station, typically with duplicate controls and entertainment space.

Freeboard

The distance from the waterline to the deck edge; higher freeboard generally indicates greater seaworthiness.

Gross Tonnage (GT)

A measure of total enclosed internal volume, not weight. Used for regulatory thresholds and marina fee calculations.

Hull Speed

The theoretical maximum speed of a displacement vessel, approximately 1.34 × √(waterline length in feet), expressed in knots.

Keel

The primary structural backbone of the hull; in sailing yachts, the weighted appendage providing lateral resistance and stability.

Knot

One nautical mile per hour (1.852 km/h or 1.151 mph).

LOA (Length Overall)

The maximum length of the vessel measured from the foremost point of the bow to the aftermost point of the stern.

M–Z

Marina

A facility providing berths, services, and amenities for recreational vessels.

Nautical Mile

A unit of distance equal to one minute of latitude, approximately 1,852 meters or 6,076 feet.

P&I (Protection & Indemnity)

Liability insurance covering third-party claims for injury, property damage, and pollution.

Planing Hull

A hull form designed to generate hydrodynamic lift at speed, rising to ride on the water surface.

Port

The left side of the vessel when facing forward, marked by a red navigation light.

Starboard

The right side of the vessel when facing forward, marked by a green navigation light.

Stern

The rear part of the vessel.

Superyacht

A privately owned, professionally crewed yacht exceeding 40 meters LOA. See superyachts.

Tender

A smaller vessel carried aboard a yacht for transportation to shore, recreation, or provisioning.

Waterline

The line where the hull meets the water surface at rest; used to measure waterline length for performance calculations.

For detailed information on yacht types, see sailing yachts, motor yachts, superyachts, and catamarans.