Recent research has shown that naval vessels relying on traditional rudder and propeller systems can increase their efficiency and manoeuvrability with the adoption of our Promas propeller and rudder system. Promas can deliver fuel savings of more than 5 per cent which can translate into increased range, boosting the capability of naval platforms.
Kongsberg Maritime’s Hydrodynamic Research Centre (HRC) in Kristinehamn, Sweden, tested and compared the Promas bulb-rudder system and the conventional off-centre rudder system used by navies on a typical naval aft ship dummy design. The dummy design consisted of an open shaft configuration with V-bracket and a high shaft inclination angle to produce a typical wake field for a naval twin screw vessel.
The testing conducted by the HRC compared propulsive efficiency, rudder forces, cavitation inception speed, cavitation, pressure pulses and noise levels between Promas and conventional navy propulsion for ship speeds up to 25 knots.
The rudder forces with Promas are also much higher. The system demonstrated less drag at small rudder angles and a higher lift at larger angles than a conventional navy system. This improves slow speed and harbour manoeuvring.
The measured pressure pulse (PP) levels were lower with the Promas set-up compared to the conventional system and noise levels were lower for the Promas system at frequencies below 1 kHz. At 25 knots, the cavitation patterns on the propeller blade were similar for both the conventional system and the Promas set-up.
For 15 years, the commercial shipping industry has used Promas to save fuel. But for naval vessels with a top speed between 20 and 25 knots, the results of HRC’s research point to significant increases in system efficiency that are within reach. Calculations done for naval vessels indicate that improvements in efficiency could go beyond the 6 per cent achieved in testing.
