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Recent events underlined the importance of an accurate intact and damage stability analysis for a ship. It’s well known that reliable information should be given to the ship Master in order to assess the ship stability for different loading and service conditions, with smart and easy tools. Such information should include the curve of the minimum metacentric height GM (or the maximum height of the center of gravity KG) as function of draft and trim, regarding the stability requirements for the specific type of ship.

One of the goals of this work is to provide a toolbox for a direct calculation of the maximum allowable KG in damage condition that meet all the stability criteria required by the reference rules. At first the method of the maximum allowable KG for the intact stability, based on the cross curves, will be introduced and subsequently it will be extended to the damage stability problem. That analysis will be carried out and developed initially by an analytical approach; the expressions of the maximum allowable KG based on the damage stability criteria for several types of ship, will be presented using the cross curves of stability of the intact hull and computing the damage by the “added weight method”. Some possible applications of the method will be shown for passenger ships regarding the required damage stability criteria. Finally a maximum allowable KG calculation will be performed on a Ro-Ro passenger ship in order to analyze the effects of the center of gravity height with respect to a standard ship subdivision.