Ik vermoed dat het roer vooral de functie had om af te breken als het geraakt werd. De bovenste helft bleef functioneren en het schip was niet meteen stuurloos.
The Contrguide - Rudder by St. Louis Ship Probably the most sophisticated rudder - ever designed, which operates just like a trim fin on aircraft - wings. Only in towboats, it cancels out the propellers - constant attempts to swing the boat in the same direction as its prop - Is Turning. With each 1/2 section having a slightly different - Pitch, these rudders steer slightly more-in "One Direction", depending upon which side of the hull - its designed to work. Meaning there's Port & Starboard version of Contrguide's, which are used on Single & Twin, as well as Triple screw boats and at one time - were also found on Quad Screws. These rudders completely cancel out the boats tendency to constantly want to turn, or torque, in the same direction as the propellers are turning - Going Ahead. Here, the lower point of these rudder, is actually offset from the upper portion, by a few degree's. The lower section, canceling out the propellers - torque, and allowing the vessel to steer more easily. On a twin screw - for example, "If One Engine Goes Down", the pilot can still continue to steer a straight coarse, without constant steering - corrections, on the remaining engine. So these rudders cancel out - prop/hull torque effects, and also save fuel and make it far easier for pilots = To Steer. Once you realize this is the realm where you fight cross winds and cross currents - in shallow waters, these rudders make a real difference and a lot of sense. Note .... Vessels equipped with Contrguide Rudders, don't have "Pintle Bearings" to hold or brace the lower part of the stern rudder on their kort nozzles. These rudders are designed to "Break-off", if damaged, leaving the upper portion still intact, so boats can continue with only reduced steering effects.