A study published by Norbert Bulten, Product Performance Manager at Wärtsilä, has demonstrated that “there is more in life than the straight-sailing, calm water condition.”
The research was carried out within the EU-funded CHEK project and involved full-scale CFD simulations that focused on the impact of rudder steering and vessel motion.
The study compared a gate rudder concept to a conventional semi-spade rudder for a Kamsarmax bulker.
Typically, a rudder is placed behind the propeller, where the movable part can be a part (semi-spade) or the complete rudder section (full-spade). The rudder profile sections can be pre-aligned with the incoming flow (twisted leading edge) or straight.
In contrast, the concept of a gate rudder has two symmetrical rudder parts located on either side of the propeller where the downstream, accelerated flow does not directly interact with the rudder. The rudder sections instead target a stagnation point of the flow close to the outer-side of the rudder leading edge. This creates a low-pressure region on the inner side of the gate rudder, which creates a net-thrust force. While both rudder parts are positioned at the same steering angle, their effect is…