PROMAS – integrated propeller/rudder

PROMAS offers increased propulsive efficiency and no loss in manoeuvrability by adapting the propeller and rudder to the hull as one propulsive unit for conventional single and twin-screw ships.

PROMAS comprises a twisted full-spade rudder with a Costa bulb that is smoothly connected to the propeller hub by a hubcap, and a propeller design adapted to the rudder.

A well-designed twist adapts the rudder to the rotation of the propeller slipstream and reduces the local angle of attack on the rudders leading edge.

This gives a more efficient rudder profile with lower drag and better recovery of rotational energy from the propeller slipstream.

PROMAS – benefit summary

• Increased propulsive efficiency by 4-6 per cent with improved manoeuvrability at high/low speeds
• Custom designed to suit single and twin-screw vessels
• Simple and robust
• Reduced pressure pulses and noise
• Almost as easy to install as a conventional propeller-rudder system

Conventional design and construction together with simple installation means the payback time for the PROMAS concept can be surprisingly short.

The best results are achieved on blunt single screw vessels with a block coefficient greater than 0.8 and a design speed in the 14 to 16-knot range. Here the efficiency gain can be as much as 6 to 9 per cent compared with conventional solutions.

Faster and slenderer single screw vessels such as car carriers can have an efficiency improvement of 2 to 5 per cent.

Vessel upgrading
We also offer a simplified version of PROMAS for vessel upgrading projects. In this case the vessel’s existing rudder is retained, but is fitted with a bulb, while the propeller is equipped with the special hubcap and new blades.

Candidate ships under investigation at present show that the propulsive efficiency should be improved by about 2 to 4 per cent, giving a payback time with current prices of less than two years and a worthwhile reduction in exhaust emissions.

Comparisson