Installing Hill Marine Signature over-hub cleaver propeller

I'm continuing the never ending quest for finding the optimal propeller for my Selva Madeira 40 outboard. I'm mainly interested to get the maximum top speed.

I have been reading lots of propeller theory and finally wanted to install a real cleaver propeller and see how it behaves.

I ordered 10 1/2" x 18" Signature cleaver for Yamaha 40-60 hp from eBay, this propeller has over-hub exhaust which means that exhaust gases go to propellers blades instead of going through the hub. In theory this kind of design should provide less drag and help with the top speed. On the other hand the hole-shot can suffer, I was willing to take that risk.

Signature 10 1/2" x 18" cleaver

Installation was very easy as I have previously installed Signature semi-cleaver propeller, I used the same XHS hub kit with slightly modified Yamaha thrust washer.

The weather was very windy so I didn't want to go for a real test drive, I only made a small test in the harbor. If I compare this propeller to Signature semi-cleaver 11 1/4 x 18 the difference is huge based on my limited tests at trolling speed. The semi-cleaver behaves more like normal round ear propeller whereas the cleaver seems to have very poor hole-shot, I raised the motor RPMs over 2500 and the boat was going only 5 knots. I think this mainly due to over hub exhaust, I'm a little afraid will the boat even plane 😅