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"Buoyancy is defined as being positive" when, in the absence of other forces or initial motion, the entering fluid would tend to rise. Situations where the density of the plume fluid is greater than its surroundings (i.e. in still conditions, its natural tendency would be to sink), but the flow has sufficient initial momentum to carry it some ...
The design of watercraft requires a tradeoff among internal capacity (), speed and seaworthiness.Tonnage is important for transport of goods, speed is important for warships and racing vessels, and the degree of seaworthiness varies according to the bodies of water on which a watercraft is used.
Buoyancy (/ ˈ b ɔɪ ən s i, ˈ b uː j ən s i /), [1] [2] or upthrust is a net upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid.
Example: A helium balloon in a moving car. When increasing speed or driving in a curve, the air moves in the opposite direction to the car's acceleration. However, due to buoyancy, the balloon is pushed "out of the way" by the air and will drift in the same direction as the car's acceleration.
When this happens wetted surface area drops radically and the boats accelerate up to 1.2 to 1.5 times the speed of the prevailing wind. These boats are very light (all up weight is less than 40 kg) and very fast, They hydrofoil in as little as 8 knots (15 km/h) of breeze ("sit on the deck breeze" for most dinghy classes).
AAW An acronym for anti-aircraft warfare. aback (of a sail) Filled by the wind on the opposite side to the one normally used to move the vessel forward.On a square-rigged ship, any of the square sails can be braced round to be aback, the purpose of which may be to reduce speed (such as when a ship-of-the-line is keeping station with others), to heave to, or to assist moving the ship's head ...
A V-shaped bow introduced in the late 1920s which allowed a ship to maintain a given speed with less power, improved seakeeping, increased reserve buoyancy, reduced pitching movements, and improved propeller immersion to increase performance in rough seas. main The high sea; the open ocean. main deck The uppermost continuous deck extending from ...
Profiling buoys are specialized buoys that adjust their buoyancy to sink at a controlled rate to a set depth, for example 2,000 metres while measuring sea temperature and salinity. After a certain period, typically 10 days, they return to the surface, transmit their data via satellite, then sink again. [ 18 ]