Vertical center of buoyancy (VCB)

The vertical center of buoyancy VCB, usually written KB as a height above keel, is the vertical position of the centroid of the displaced volume. It is found by integrating the section areas vertically over the underwater hull and is read against draft from the curves of form. KB feeds the metacenter height: KM = KB plus BM, where BM = I_T / V. For typical ship forms KB falls near 0.52 to 0.58 of the draft, higher for full sections and lower for fine ones; Morrish’s and Normand’s rules give quick estimates. As the ship heels, the buoyancy centroid moves outboard and upward, generating the righting arm.