Theory of operation
While sailing, the blades of the feathering propeller weather
vane to reduce drag. Under power forward the center of water pressure on the blades is aft of the point of rotation (the spindles)
causing the blades to rotate to the forward stop pin. An adjustable set screw in the blades controls the exact pitch. In reverse,
the drive torque causes the reverse cam to rotate the blades to the reverse position so the prop acts like a fixed prop in
reverse.
Because the propeller is designed to optimize motoring performance as will as feather, there is considerable twist
and lift built into the blades. While sailing, this can cause the outer hub/blade assembly to rotate around the reversing
cam, forcing the blades into the reverse position. To prevent this, there is a drag screw which prevents this rotation. That
same twist and lift from the blades will cause the prop and shaft to rotate slowly while under sail, even when feathered,
if the engine is left in neutral. To prevent this (if desired) put the engine in gear or use a shaft lock.
To insure proper feathering, power in forward immediately prior to shutting the engine
down. If you shut down after being in reverse, the blades will stay in the reverse drive position and will not feather. Idling
in neutral will not change the blade position.
