MAX-PROP | Automatic Feathering Propellers

Overview

Under sail, a Max-Prop will increase sailing speed between 10% to 15% in average wind conditions, compared to a fixed blade propeller, with an even larger difference being given when sailing in light air. The drag under sail varies widely between propellers, number of blades or angle of the shaft as well as the location of the propeller on the boat.

It is fair to say that a 2-blade Max-Prop propeller located on a horizontal shaft (sail-drive) will have the least drag, whilst a 5-blade Max-Prop on a high angle shaft will have the most drag. However, even a 5-blade Max-Prop on a high angle shaft will have substantially less drag and provide more power when motoring than a fixed 2-blade propeller.

In forward: the Max-Prop will offer 96% of the efficiency of a fixed blade propeller of the same diameter and pitch. The 4% loss in power can usually be eliminated by precisely matching the pitch of the Max-Prop to fit the boat engine combination.

In reverse: the Max-Prop provides 80% more power than a comparable fixed blade propeller. The Max-Prop utilises the same leading edge in forward as it does in reverse giving the propeller the same efficiency in both directions, whereas on a fixed blade propeller in reverse the trailing edge becomes the leading edge therefore reducing its power.

Max-Props are feathering propellers, so unlike folding propellers, Max-Props do not rely on centrifugal force to open. Instead, the Max-Prop relies on the torque from the shaft rotation acting on the differential type gear design in the body of the propeller. This in turn ensures an immediate opening in forward and, more importantly, in reverse – unlike folding propellers which have a lag time in reverse.