Promas integrates the propeller and the rudder into a single system to optimise hydrodynamic efficiency. A special hubcap is fitted to the propeller which streamlines the flow onto a bulb that is added to the rudder, effectively reducing flow separation immediately after the propeller. The result is an increase in propeller thrust as previously wasted energy is recovered from the flow. The addition of the bulb on the rudder also streamlines the flow aft of the rudder, further reducing drag. A twisted rudder provides further improvements in efficiency and manoeuvrability. In general the efficiency gain is between 3-8% for single screw vessels and 2-6% for twin screw vessels. Virtually any vessel will benefit. The position of the rudder in the slipstream and the skeg design can deliver further improvements.
Reduced fuel consumption
Reduced environmental impact
Short payback period
Increased propulsive efficiency