Promas is an integrated propeller rudder system that offers increased propulsive efficiency without any loss in manoeuvrability. The propeller and the rudder are considered as one propulsion unit and are designed together for optimum propulsive efficiency.
The rudder design is adapted to the particular propeller design and is optimised to regain losses from the propeller slipstream, whilst the propeller design utilises the presence of the rudder bulb and hubcap to recover losses behind the propeller hub.
Promas comprises of a twisted full-spade rudder with bulb that is smoothly connected to the propeller hub by a hubcap, and is adapted and optimised to the propeller design.
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 with lower drag and better recovery of rotational energy from the propeller slipstream.