I just completed the upgrade of the prop on my F-40 to a 3 blade Featherstream.
I had to replace the cutlass bearing so I decided to upgrade the prop while i was at it. There was some discussion a while back on whether a kiwiprop would fit so I figure I would share in case it helps.
I checked several models and it was hard to find a prop that would fit in the operture. Ended up a with a three blade Featherstream. The increase in performance both sailing and motoring is VERY impressive .
cheers,