Whereas previous chapters dealt with the water flow and the corresponding pressure force and moment on the hull, this chapter describes approximations of other influences. Especially the small moments in excitation, restoring, and damping of roll motions require to take account of additional influences, e.g., fins, of the lift effect of hull and rudder in oblique flow, of the roll damping by bilge keels, and of the control forces required to keep the ship’s intended speed and track both in reality and during simulations. Also recommendations are derived for the required control forces to attain stable motions not overly influencing the free motions. Often neglected effects are included, e.g., the influence of the stern wave on metacentric height, which may amount to about 1 m for 15 knots speed.