Dry Exhaust

Dry Silencer with water injection downstream of the silencer

This arrangement is typical of many large yachts and has the advantages of simplicity and effectiveness. A dry silencer, mounted above the engine, is predictable both in noise attenuation and back pressure. Downstream from the silencer the engine’s cooling water is injected through a specialist spray ring, both cooling the gas and offering further noise attenuation. This connects via flexible bellows, and above waterline, to the thru hull outlet below waterline which functions as soon as the vessel achieves a given speed. The by-pass above waterline is used below this speed, or when the vessel is stationary. A neat, simple and predictable system. The most complex task is the design of the underwater outlet, which must “draw” the exhaust gas out when the vessel is moving to maintain the low exhaust gas back pressure level required by the engine manufacturer.