I did some looking and the range of possible lakes is 6-8000 feet, but around 7 is the most common. I’ll report back as soon as I have some hard rpm data.
Ya RPMS are everything. Its a great starting point. The other thing you can really play with is jackplates and getting away with getting RPM by bringing the outboard up and using a higher pitch prop. Go too high though and you get too much slip, go too low and you arent getting the RPMS and bite and then you are at the same spot you are now. If you go to high, you will notice handling issues like porpoising and you will know its not right. Also, the rule that was always taught to me with outboards was the rooster tail should be the height of the cowling. If over, motor is too high and if lower, motor needs to come up. Not ALWAYS the truth for every case, but thats a good rule of thumb to get started with JP's. Brining the motor up with the JP was when I found my performance to be the absolute best all the way around. Highest top end with pretty damn good hole shot all the way around. I really just need to repower to a 200 hp on my bass boat or lose a few soft plastics because I run with half of bass pro in that damn thing, but this 150 opti just wont go boom on me and it just keeps purring down the lake. I cant wait to go 4 stroke as well.
If wanting to play with JP, I would highly recommend the hydrodynamics JP. BEYOND easy to adjust and rock solid. I like the cog system that it uses and how you can adjust 1/4" at a time per tooth of each cog wheel. They are reasonably priced, not the most expensive and not the cheapest but imo one of the coolest systems out for a JP.
Not sure about yammies props, but like with my tempest plus prop I use on my bass boat, I can also play with vent holes. What this does is when the prop first spins, when i give it throttle, it creates air bubbles around the shaft of the prop. This actually creates slip, because of air going around the prop, which in turn gives me more rpm initially, but as the boat gains MPH, the bubbles become less and less around the prop and the prop starts to grab more and more, but at a dead stop, there is that initial higher RPM that helps with hole shot. This is also likely the only reason I can still get my boat up on plane at the 7k lakes with my 19p because some calculators say I should be as low as 15p at that elevation with my boat set up. When I played with opening up vent holes, I saw about 100-150 more rpm with every hole I opened up. Some say you lose top end speed with vent holes open, but I just didnt see that at all. I saw top end speed lost with lower pitch props, so all vent holes got opened up on my prop.
On a mudmotor, there isnt near as much as this. I dont have good luck with a 3 blade, but the 2 blade "big blade prop" is the absolute best performer. The bigger Mudbuddy does fine on hole shot and it has the rpms at the sweet spot to get up to 30 mph with a load. The hammer prop literally makes my boat feel like it jumps out of water when I hit the throttle but the max speed is only 22-24 mph and thats because where I get the RPM, its just slipping and im throwing a 20 foot rooster tail and when i trim down to the sweet spot, im not getting the rpm, like due to elevation. I keep hearing REALLY good things about the Roost marine props for mudmotors and want to give one a shot. Apparently they have figured out a prop that has even less slip, in turn this allows for shallower angles for getting the boat on plane and get going quicker out of even shallower situations.
One last thing Tod, at elevation, you will realize EFI is your absolute best friend. Our first mudmotors were carbed and a PIA! We would have to change jets on the carbs to get performance needed based on which areas we were hunting and the elevation. EFI changed all of that. Start it up and roll and the computer system controls the injectors based on performance of the motor.
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