Stuwa® Flanking stirring

The manoeuvring efficiency of rudders is normally based on the deflection of propeller water. However, when sailing astern, no stern water hits the rudder blades. When the rudders are set completely sideways, the ship hardly responds at all when reversing. In some situations, rudders in front of the propeller are the solution: these are known as flanking rudders.

Normally, 'reverse steering behaviour' is not that important. After all, inland vessels have a bow thruster for steering. This also applies to seagoing coasters. Large seagoing vessels use tugboats in ports. But for push boats, the situation is different. Large convoys travelling backwards with many barges without their own propulsion are at the mercy of the wind. Push boats therefore have great difficulty turning straight backwards or making short reverse turns. This is quite dangerous among other shipping traffic. In such situations, De Waal recommends its flanking rudders.

Independent control

Flanking rudders are controlled by an independent steering machine. This allows the captain to operate two rudder sets separately and effortlessly keep his convoy on course when reversing. During normal forward sailing, the rudders remain stationary in the neutral middle position.

Rudder dynamics

The flanking rudders resemble balance rudders in terms of shape and profile. However, their size and proportions give them a slightly different appearance. Straight ahead, no resistance. Reverse, optimal deflection of the propeller water. The number of rudders required and their location and size are determined precisely for each ship by De Waal's engineers.