Abstract: A boat trailer modified to include a load-bearing trolley and a track; the trolley is movable along the track along a direction parallel to the length of the trailer, and the ends of the track correspond to the fully launched and fully loaded positions of the boat on the trailer. A belt with ends attached to the ends of the trolley is moved by a sprocket connected to a hand crank, through a set of sprockets and idler rollers. Rotating the hand crank causes the belt to move, thereby causing the trolley to move along the track, resulting in movement of the boat to either launch it into the water or load it onto the trailer. A latch mounted on a docking plate on the trolley automatically latches or releases the tow ring depending upon the position of the trolley along the track.