Abstract: A propulsion system for a boat including a drive system and a propeller positioning system. The drive system may be of any type, such as outboard motors, inboard/outboard drives, surface drives, etc. The positioning system constrains movement of the propeller shaft to swing in a path generally parallel to the bottom surface of the boat. The boat has a hull with either a flat or a sloped bottom surface. Various positioning systems include bite bars, bite rams, cambered drives, jack boxes, jack plates and various linkage configurations. In one aspect a tie bar links multiple drives together. In another aspect, a four-bar steering linkage enables variations in immersion depths of multiple propellers while maintaining constant toe-in. In yet another aspect, yaw steering is achieved using differential immersion between multiple propellers.