Standard equations of motion are presented for use in submarine simulation studies being conducted for the U. S. Navy. The equations are general enough to simulate the trajectories and responses of submarines in six degrees of freedom resulting from various types of normal maneuvers as well as for extreme maneuvers such as those associated with emergency recoveries from sternplane jam and flooding casualties. Information is also presented pertaining to the hydrodynamic coefficients and other input data needed to perform simulation studies of specific submarine designs with the standard equations of motion.