New prop results on overnighter

[roughrider123]

Took the 90 overnighter out for trial run with new prop last weekend and it resulted in excellent results. I bought this rig 2 years ago and after researching this winter I picked up a solas 13 7/8 dia, 4 blade 15 pitch aluminum. It would only top out around 5300 with a 18 pitch Ss 3 blade. Well I got her up to 6200 with 2 people and full tank max speed 34 which came in at 8 percent slip. Hole shot was good and held plan at 4000 into a stiff wind. The engine even sounds better. What a waste of engine power the previous owner missed. Engine is 06 suzuki 140 4 stroke with 250 hours.

 

[SmokyMtnGrady]

I was skimmingt the threads and stumbled upon yours. I am not an expert on props or motors mind you, but reading your results two things pop out at me. I know the sweet spot for RPMS is around 6K and it seems, and I could be wrong here, that your motor is slightly over revving. Dont know if this is an issue over the long haul or not. I also noticed the speed of 34 mph. I had a 192 with a F150 and it would run 43 to 44. The Overnighter is a bit bigger in terms of weight and length, not much mind you, but 34 seems low even with a 140. The prop being aluminum might have a factor here since aluminum flexes and your boat is powered towards the low end meaning your motor "works a little harder" because it has more of a load to push and thus that aluminum prop is flexing. Flexing translates into a loss of power or wasted energy thus lower performance. I know budgets can be tight, but perhaps when you can, maybe you might want to consider a slightly larger 4 blade steel prop in diameter and keep the pitch. I put on a 4 blade prop last year and love it. My top end is only .5 to 1 mph less but my overall performance is improved including fuel economy.

 

[roughrider123]

Thanks for reply. Specs out at 6200 max rpms. I agree with flex, wanted a cheaper option to try first. Will probably go Ss at some point. Would like to hear other opinions on their props for the overnighter with a 150 hp option.