A sailboat or sailing boat is a boat propelled partly or entirely by sails smaller than a sailing ship. Distinctions in what constitutes a sailing boat and ship vary by region and maritime culture.
The bilge is the lowest compartment on a ship or seaplane, below the waterline, where the two sides meet at the keel. The first known use of the word is from 1513.
On boats and ships, the keel is either of two parts: a structural element that sometimes resembles a fin and protrudes below a boat along the central line, or a hydrodynamic element. These parts overlap. As the laying down of the keel is the initial step in the construction of a ship, in British and American shipbuilding traditions the construction is dated from this event. Only the ship's launching is considered more significant in its creation.
The metacentric height (GM) is a measurement of the initial static stability of a floating body. It is calculated as the distance between the centre of gravity of a ship and its metacentre. A larger metacentric height implies greater initial stability against overturning. The metacentric height also influences the natural period of rolling of a hull, with very large metacentric heights being associated with shorter periods of roll which are uncomfortable for passengers. Hence, a sufficiently, but not excessively, high metacentric height is considered ideal for passenger ships.
Boat building is the design and construction of boats and their systems. This includes at a minimum a hull, with propulsion, mechanical, navigation, safety and other systems as a craft requires.
Clinker built is a method of boat building where the edges of hull planks overlap each other. Where necessary in larger craft shorter planks can be joined end to end into a longer strake or hull plank. The technique developed in northern Europe and was successfully used by the Anglo-Saxons, Frisians, Scandinavians, and typical for the Hanseatic cog. A contrasting method, where plank edges are butted smoothly seam to seam, is known as carvel construction.
A double bottom is a ship hull design and construction method where the bottom of the ship has two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull which is somewhat higher in the ship, perhaps a few feet, which forms a redundant barrier to seawater in case the outer hull is damaged and leaks.
The Bevaix boat is a 1st-century Gallo-Roman wreck from the Bay of Bevaix, Lake Neuchatel, Switzerland. The remains of the ship, and a modern reconstruction, are on display at the Laténium archeology museum.
The Adventuress sailing dinghy class was designed by Ian Proctor and built by Anglo Marine of Essex. It is no longer in production.
The harbour defence motor launch (HDML) was a British small motor vessel of the Second World War.
A bilge keel is used to reduce a ship's tendency to roll. Bilge keels are employed in pairs. A ship may have more than one bilge keel per side, but this is rare. Bilge keels increase hydrodynamic resistance to rolling, making the ship roll less. Bilge keels are passive stability systems.
The Kadakkarapally Boat is a shipwreck found near Kadakkarappally, in the Southern India state of Kerala.
The stem is the most forward part of a boat or ship's bow and is an extension of the keel itself. It is often found on wooden boats or ships, but not exclusively.
Longitudinal framing is a method of ship construction in which large, widely spaced transverse frames are used in conjunction with light, closely spaced longitudinal members. This method, Isherwood felt, lent a ship much greater longitudinal strength than in ships built in the traditional method, where a series of transverse frames were fit together closely from the keel upwards.
Lepa, also known as lipa or lepa-lepa, are indigenous ships of the Sama-Bajau people in the Philippines, Malaysia, and Indonesia. They were traditionally used as houseboats by the seagoing Sama Dilaut. Since most Sama have abandoned exclusive sea-living, modern lepa are instead used as fishing boats and cargo vessels.
