A pump jet apparatus for a motor includes an annular exhaust channel to receive exhaust gas from the motor. At least one hollow exhaust vane extends radially from a vane hub surrounding the annular exhaust channel. The at least one hollow exhaust vane is in flow communication with the annular exhaust channel to discharge the exhaust gas received from the motor through an exhaust discharge outlet. An impeller driven by the motor is mounted rearward of the annular exhaust channel and the at least one hollow exhaust vane and exhaust outlet.

THIS invention relates to a propeller and more particularly, but not exclusively, to a propeller for use with inboard and outboard boat engines. The propeller includes a hollow hub and a plurality of primary blades extending substantially radially outwardly from the hub, with each primary blade including a blade face, a blade back and a root section. The propeller is characterized in that a set of secondary blades are provided inside the hub, and that an inner volume of the hub is in flow communication with a volume radially outwardly of the propeller hub.

An aeration control system and method for a marine vessel. The system includes a valve configured to be coupled to an aeration conduit of a marine vessel. The valve is configured to be responsive to a valve control signal having a first value so as to be open and to provide air to the aeration conduit, and the valve configured to be responsive to the valve control signal having a second value so as to be closed and not provide air to the aeration conduit. The aeration control system also includes a control device, electrically coupled to the valve, that provides the valve control signal to the valve

An aeration control system and method for a marine vessel. The system includes a valve configured to be coupled to an aeration conduit of a marine vessel. The valve is configured to be responsive to a valve control signal having a first value so as to be open and to provide air to the aeration conduit, and the valve configured to be responsive to the valve control signal having a second value so as to be closed and not provide air to the aeration conduit. The aeration control system also includes a control device, electrically coupled to the valve, that provides the valve control signal to the valve