Well its been about a year and thought I would update this old thread with some new stuff. Since last time, I've been working with a guy in MO on some props. Have also tried some Hill Marine 4x4 and others. Some of the stuff I was making matters worst. I was trimming up and getting no more speed just more rpm's. This is where I was messing up. For a brief replay, the boat is heavy and before I rebuilt the transom it was about 3 to 500 pounds heavier from water soaked hull.
Thinking that I could just start with the trim I'm use to was also a wrong way to think. I needed to start with a new baseline. So we started by finding where the drive was flat and level with the bottom of the hull. Then we started running different props.
So here are the numbers
These were all done on one day, water calm, no wind, 1/2 tank fuel
4x4 24 pitch, WOT 4900 rpm, 41 mph = 26.37% slip
3x3 22 pitch cupped, WOT 5200 rpm, 45.2 mph = 16.55% slip
3x3 24 pitch, WOT 5000 rpm, 43.8 mph = 22.91% slip
This set done another day
3x3 22 pitch modified, 5200 rpm, 45 mph = 16.92% slip
The last set of props was run at 1/4 tank fuel and almost 3/4 tank fuel, also water tank (20 gallon) full and empty, and there was little change in the speed/rpm/slip numbers. What we learned is that this is a heavy boat and hard to push. Even if I trim up (bump trim), wait a few seconds, bump up again, wait a few seconds to see if speed increases (and it does not). The cupped prop is the way to go, so even though we have a higher slip number, the cupped props keep the props connected.
Plan forward: calling Hill to see if I can exchange the 24's for 22's and see if I can get them cupped. Looking into see if we can find some 3x3 from Merc with a bit larger diameter prop. Also looking into different rakes and cupping to see what can change.
Looks like