Marine Surveyors Lexicon

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

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B - (Center Of Buoyancy)


Is the center of mass of the underwater body of the ship and the point through which the force of buoyancy equal to the weight acts vertically upward. The longitudinal position of B (LCB) is import because, when the ship is afloat, B and G are in the same longitudinal position. If they are displaced form one another, the ship trims until the two centers are in the same longitudinal position. When the ship is aground it may be unable to trim, so there is a considerable longitudinal distance between B and G.

In most ships, the height of the center of buoyancy above the keel (KB) lies between 0.53 and 0.58 of the ship's mean draft, depending upon the shape of the ship's bottom. A reasonable quick first estimate of the height of KB is 0.55 times the mean draft.