Unconventional, High-Efficiency Propulsors

The development of ship propellers has generally been characterized by search for propellers with as high efficiency as possible and at the same time low noise and vibration levels and little or no cavitation. This search has lead to unconventional propulsors, like vane-wheel propulsors, contra-rotating propellers, propeller-and-stator-blade propulsors, and also to propellers with unconventional geometry, like propellers with end plates and tip-fin or Kappel propellers.

The paper starts with a short overview of the different unconventional, high-efficiency propulsors. The emphasis is laid on the background, development and current state of development of tip-fin propellers.