Prop help needed!!

[60MPHjonboat]

I have a 1448 semi v riveted aluminum boat with a 48 special on it, 2 cylinder, 2 stroke. 6 inch jackplate. Power tilt and trim. Engine has 150 lbs compression on both cylinders. The boat loaded with fuel, battery, anchor and all weighs 800 lbs. The problem is that I am turning 6100 rpms with (2) 200lb adults in the boat at 39 MPH on GPS. I am currently running a 11 3/4 x 17 aluminum prop. I have tried several of my buddies props from 15's to 19's and all over rev. I went to my local prop shop and they told me that my best bet would be to ask around because they have never propped a setup like mine. The largest SS prop he could order me for my motor was a 17P. Said he could pitch it an inch and double cup it making it an 18 1/2 but he didn't think that would bring my rpms down where they needed to be. I am looking for maximum top speed out of the boat. I am aware that I can't have the best of both worlds. I have found custom props online for my motor such as cleavers and choppers in 19 and 20 inch pitch but I don't know the advantages and disadvantages of all the different style props that are offered. Any advice is appreciated.

 

[Faztbullet]

You dont want a chopper or cleaver as that gearcase wont handle them as the gears will fail. If you can find a shop or boater thatr has a Solas Amita 3 in a 12x17 that should drop your RPM by 300-400rpm. These blades are wider and hold more water thus reducing RPM.

 

[Sea Rider]

What's the min-max wot rpm range factory stated for than engine to know how much wot rpm engine needs to drop to rev safely around max wot rpm range.

Happy Boating

 

[60MPHjonboat]

Min/Max 4500-5500 RPM @WOT