Waterjet flow emerging from a jet propulsor body through a cross-sectionally circular duct is conducted through a cross-sectionally rectangular duct passage extending through transition and exhaust aft sections attached to and angularly adjusted relative thereto. Under selective maneuver controls within the propulsor body, the transition section is angularly adjusted relative to the body while pivotal vanes and flaps on the exhaust section are angularly adjusted to direct exit outflow through the exhaust section for steering and reversing purposes.