The new propellers were originally fitted with "Grim Wheels", named after their inventor, Dr. Ing Otto Grim. These were free-spinning propeller blades fitted behind the main propellers, with long vanes protruding from the centre hub. The Grim Wheels were designed to recover lost propeller thrust and reduce fuel consumption by 2.5 to 3%. After the trial of these wheels, when the ship was drydocked, the majority of the vanes on each wheel were discovered to have broken off. The wheels were removed and the project abandoned.