Martec Folding Prop
based on my experience years ago, you should call Martec and provide them the shaft diameter, the motor horsepower and transmission ratio, the clearance from the end of the shaft to the rudder and from the end of the shaft vertically to the underside of the hull. They can give you one or more options on the diameter and pitch; the larger diameter possibly providing better centrifugal force for 'opening' the prop.
