Finally got a chance to get my project in the water this weekend. Tried some 18x28 merc 3 blades that my friend let me borrow. Planing was pretty tough, pretty much 4k rpm and took a while to hook up and lay over.

The boat feels like it needs more stern lift. I was able to turn the 28's to 5500rpm on flat water. I'd like to try some 4 blades and be around 5300 on flat water. Props are turning in. Would say a 17.5x28 be what i want in a 4 blade?

Also, what is the difference between a old rolla 4 blade and a old merc 4 blade in the 19 spline props?

17.5x29 would be the prop I would be looking to try next.

I believe the Rollas had a higher rake angle.

Brett

Cool Rear plates in action

Brett, in regards to rake, what exactly does more rake do? Bow lift?

Tried some 17x28 Four blade mercs and could not get the boat on plane at all. Water was pretty calm. Tried every possible trick to get it to lay over and they would not hook up at all. Which seems weird considering the 18x28 3 blades would get the boat on plane???? Ended up having to put the 3 blades back on to go boating this weekend.

Rake is the angle in which the blades are attached to the hub. More rake will create more bow lift since the water can't escape the blades as easily. Rake can also create drag and slow you down. Depending on the hull and other variables, rake can help or hurt. We can offerer you advice in this regard.

Brett