An Alternative approach to determine a vessel's center of gravity: the center of buoyancy method

Abstract

The location of a ship's vertical center of gravity ( KG) is an important measurement needed to estimate the initial stability of a vessel. Traditionally, this measurement is obtained by determining the metacentric hight ( GM) using results from the inclining experiment. Such an approach is valid only for hull forms that are inclined to a small angle such that the metacenter remains stationary. This paper documents an alternative method for finding KG, called the center of buoyancy (CoB) method, which is based on the location of the centroid of the displaced volume. While the center of buoyancy method is valid for all ships, it is especially suited for vessels of unusual form. For such vessels, the location of the metacenter may change significantly at small angles of inclination, thereby making the conventional inclining reduction inaccurate. This paper addresses the need for the center of buoyancy method and details the steps required for its application.