Abstract: A safety light apparatus is provided for a trailered boat including an inboard or outboard propellered motor. The apparatus designed to be detachably mountable on a hub of the propellered motor. The apparatus preferably comprises a housing with a mounting recess, which is adapted to receive the hub, formed in a rear side thereof and a light assembly disposed on a front side of the housing. The light assembly preferably comprises a tail/brake light, which may include a back-up light, and an electrical connection assembly for electrically connecting the light assembly to a vehicle towing the trailered boat. The tail/brake light may be arranged to emit light pulses in response to application of the brake pedal of the vehicle. The safety light assembly may also comprise a back-up sensor installed on the housing which emits a warning signal upon detection of an obstruction. Preferably, the warning signal has an intensity which is dependent upon the distance between the obstruction and the back-up sensor.