A deflector for offsetting a streamer being towed by its lead-in by a seismic survey vessel comprises a wing-shaped body which is coupled to the lead-in and shaped to produce a sideways force which urges the lead-in laterally with respect to the direction of movement of the vessel. A primary motor or generator is coupled to an output shaft of the planetary gear train for receiving power therefrom, and a secondary motor or generator is associated with each driven vehicle wheel to provide an electrical power pathway. Physicians are assigned to report groups, and eligible physicians and episode assignments are determined. In another embodiment, the inner facing surface of the sidewalls includes at least one spring-loaded member for securing the main body against the outer facing wall of the speaker grille.