Shaped rudder
As the wash of the propeller does not enter at the same angle rudders (sometimes called 'slopped') with uneven inlet angles are sometimes fitted to even the flow from the propeller. Asymmetric hull
Another design involves the use of design. The water is directed in the same direction as the blade rotation and hence the shock loading occurring when the blade hits relatively still water is removed Increasing number of blades and skewing
An overlap can be arranged to reduce the pressure fluctuations and change the forcing frequencyHalf Kort (Port Nozzles)
Consists of two half loops mounted either side of the hull which smooths the flow of water into the propeller