Stability and roll angles of the ship at its small finite tilts from different starting positions

Abstract

The article, within the framework of the acceptability of the metacentric formula, presents a solution to the problem of comparing the stability of the ship, the angles of rotation and the roll angles that it takes while in different starting positions: in a straight state (with the center of gravity  (CG) unbiased from the diametrical plane) and with the initial roll angle (with the displaced CG). This comparison is carried out when the following factors affect the ship: the same heeling moment; the rotation of the ship at the same roll angle; the transfer of the same cargo parallel to the deck at the same distance; the inclination of the ship to the same position. The purpose of this comparison is to clearly show that a ship with a displaced CG exhibits better stability within the specified framework than in a straight state. It is shown that the transfer of cargo in any direction from side to side will turn the ship with the initial angle by a smaller angle in the direction of transfer than the same ship in the initial straight state. The exception will be the same transfer, in which the initially cloned ship will restore a straight state or take a roll opposite to the original one. In the first case, the rotation of the ship (relative to the initial roll) will occur at exactly the same angle as when the ship is tilted with an initially straight state, and in the second case - by a larger angle. The materials of the article can be useful in analyzing the behavior of a ship at small roll angles.