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AUTO ROTATION WHEN SAILING: To ensure the propeller feathers correctly once sailing: First throttle down to an engine idle for say 20 seconds, then place the gearbox in neutral, then stop the engine. The shaft will then slow down as the blades align themselves with the water flow and slowly come to a stop. The shaft will then remain stationary or near stationary without further attention. This may take 2 - 3 minutes. If the units are rotating slowly - you can either keep them in this condition - they are still feathered as even the smallest angle of incidence can cause rotation with uneven streamlines off the Saildrive leg, keel, shaft or bracket. You can keep the gearbox in neutral when sailing (which will allow any movement of the shaft), or ... engage reverse only once the shaft has stopped rotating by luffing up or engaging reverse only prior to bearing away when sailing. Do not engage reverse while the shaft is rotating as this will engage Reverse ie Ahead Engaging reverse while the shaft is rotating will usually not work as the rotating momentum of the unit will in effect wind up the spring and in effect engage reverse - the very objective we are trying to avoid. The prop once stopped will then remain feathered. In gear - it will still be feathered but the blades will have a very low angle of attack with very minimal increases in drag. The Kiwiprop approach of individually feathered blades will always have less drag than a geared feathering unit where the blades are geared together and will always present an increased projected area with consequent drag increases in real world operating conditions. So - if you place the unit in gear - do so before it starts to rotate. All the text books say there is a lot of induced drag from a rotating prop. In addition this will reduce wear from the individual blade oscillations induced by the shaft angle as the unit rotates. The best example one can use is a helicopter gliding down without power in auto rotate mode. For maximum lift - you want the blades rotating as fast as possible. This equates to maximum drag on a rotating prop. It's all about the rotating energy left in the wake. So contrary to initial thoughts a locked prop will usually have less drag than a rotating prop. The above all assumes the following which would need to be checked if the unit fails to feather:
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