A propulsor and control system for an underwater vehicle having annular fore and aft circumferential shrouds surrounding the hull. The fore and aft circumferential shrouds form respective fore and aft circumferential shroud gaps between the fore and aft circumferential shrouds and the hull. Fore and aft propulsor blades are situated substantially or completely within the fore and aft circumferential shroud gaps; the blades counter-rotate in one preferred embodiment. The fore or aft circumferential ring propulsors can have front control vanes located in front of the respective propulsors blade sets, and back control vanes located behind the respective propulsors to control the direction of the flow of water in order to maneuver the underwater vehicle.