When calculating the KN cross curves of stability, the curve is plotted for an assumed KG of zero, and KN is the righting lever measured from the keel. Therefore, the curve assumes that the center of gravity is at the keel. The KN curve is used to obtain the righting lever for a particular displacement and KG. The value of KN is first obtained from the curve at the displacement concerned, and the correct righting lever is then obtained by subtracting from the KN value a correction equal to the product of KG and sin heel.