Abstract: The invention is a two-wheeled, battery powered, trailer dolly that may be coupled to a boat or other vehicle for facilitating the movement of such vehicles. A deep-discharge, marine battery powers a winches which operates the axle of the dolly. The axle has an inner collar at each end with abutment portions that interact with similar abutment portions on an outer collar in connection with the wheels. The use of the inner and outer collar arrangement provides for separate turning of each wheel through turns. The dolly utilizes a trailer ball in order to allow a rotatable coupling of the trailer at the ball and not on a trailer jack as shown in prior art.