Manufacturer: IMC Co., Ltd.
Product: Rupas (High Lift Rudder)

Introduction

RUPAS is a rudder with a smaller roundness at the tip and a hollow and parallel section at the rear end compared to conventional rudder cross sections. As a result, it has the characteristic that it can obtain high lift at the same rudder angle, while the rudder resistance (rudder angle 0°) is slightly smaller than conventional rudder.

Rupas

Conventional

Rudder Forces

When the rudder is at a certain angle (rudder angle) δ in the propeller wake, a direct force Fry is generated on the rudder.
The component parallel to the flow of the direct force is drag, and the perpendicular component is lift. Lift creates a moment that bends the ship.

Rudder Normal force & Resistance

The graph on the left compares the direct pressure of RUPAS and normal rudder at each rudder angle. From this graph, we can see that at the same rudder angle, RUPAS has about 12% greater direct pressure than normal rudder. Additionally, the graph on the right compares the rudder resistance of RUPAS and normal rudder at a rudder angle of 0°. From this graph, we can see that RUPAS has slightly less rudder resistance.

Comparison of direct pressure between normal rudder and RUPAS

Comparison of rudder resistance between normal rudder and RUPAS