Location of ship rolling axis

In the paper is presented a definition of ship rolling axis and a method for determination oflocation of the axis. Location of rolling axis depends not only on ship mass distribution butalso on the so-called 'added masses' which are equivalents of the hydrodynamic forces acting on ship hull during its motion. It has been assumed that the rolling axis is fixed withrespect to ship's hull, and its location is determined with accounting for the added massesaccompanying ship rolling, whereas the influence of damping forces is neglected. Fora representative group of ships appropriate coefficients of hydrodynamic forces were cal-culated on the basis of the experimental test results available in the subject-matter literatu-re. It has been assumed that the rolling axis passes through a common centre of ship's mass and relevantadded masses. As a result proposed are simple approximate formulas which make it possible to calculatelocation of ship rolling axis on the basis of the typical ship data available at the preliminary design stage.