SonarSonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on or under the surface of the water, such as other vessels. "Sonar" can refer to one of two types of technology: passive sonar means listening for the sound made by vessels; active sonar means emitting pulses of sounds and listening for echoes.
Draft (hull)The draft or draught of a ship's hull is the vertical distance between the waterline and the bottom of the hull (keel). The draught of the vessel is the maximum depth of any part of the vessel, including appendages such as rudders, propellers and drop keels if deployed. Draft determines the minimum depth of water a ship or boat can safely navigate. The related term air draft is the maximum height of any part of the vessel above the water. The more heavily a vessel is loaded, the deeper it sinks into the water, and the greater its draft.
Deck (ship)A deck is a permanent covering over a compartment or a hull of a ship. On a boat or ship, the primary or upper deck is the horizontal structure that forms the "roof" of the hull, strengthening it and serving as the primary working surface. Vessels often have more than one level both within the hull and in the superstructure above the primary deck, similar to the floors of a multi-storey building, that are also referred to as decks, as are certain compartments and decks built over specific areas of the superstructure.
Naval architectureNaval architecture, or naval engineering, is an engineering discipline incorporating elements of mechanical, electrical, electronic, software and safety engineering as applied to the engineering design process, shipbuilding, maintenance, and operation of marine vessels and structures. Naval architecture involves basic and applied research, design, development, design evaluation (classification) and calculations during all stages of the life of a marine vehicle.
Inflatable boatAn inflatable boat is a lightweight boat constructed with its sides and bow made of flexible tubes containing pressurised gas. For smaller boats, the floor and hull is often flexible, while for boats longer than , the floor typically consists of three to five rigid plywood or aluminium sheets fixed between the tubes, but not joined rigidly together. Often the transom is rigid, providing a location and structure for mounting an outboard motor. Some inflatable boats can be disassembled and packed into a small volume, so that they can be easily stored and transported.
CatamaranA catamaran (ˌkætəməˈræn) (informally, a "cat") is a multi-hulled watercraft featuring two parallel hulls of equal size. It is a geometry-stabilized craft, deriving its stability from its wide beam, rather than from a ballasted keel as with a monohull boat. Catamarans typically have less hull volume, smaller displacement, and shallower draft (draught) than monohulls of comparable length. The two hulls combined also often have a smaller hydrodynamic resistance than comparable monohulls, requiring less propulsive power from either sails or motors.
