Real World Tests of Turning Point Hustler vs. Stock Prop on 75 HP Evinrude

[sutor623]

Okay fellas I am back again

I did a little reading of my records about WOT runs with my stock prop. I realized that when I got 6000RPM's out of the motor I didn't have the intake manifold (plastic box) installed on the carb air intakes. Once I installed them, it brought my RPMs down to 5850.

So the actual stock prop WOT figure is 5850 and 32MPH (GPS), which figures in at 6% prop slip. Not sure if this is reasonable or my tiny tach was reading off.

Did some runs this weekend with a heavy load and a light load. Trimmed the motor out as much as possible without porpoising.
Normal load trimmed to the max was running 32.4 MPH at 4900 RPMs.
Light load trimmed out was running 5000 RPMs, but my GPS battery was dead. Either way, difference between light and normal load is only about 100RPM's.

So using the 17p cupped prop (18p) in the calculator I get 6% slip yet again. Should I figure 9% slip and suggest that my tach is reading off?

 

[Rancherlee]

Something it wrong with your setup somewhere, a 75hp shouldn't have any problem swinging a 17 pitch on your boat. I used to have a 87' Lund pike 16' with a heavy johnson 70hp 4 stroke on the back with the same 2.42 gear ratio and it had NO problem running 37-38 mph swinging an 18 pitch stainless and it over revved with a 17p hustler running 35mph. Even with 4 big guys and a full live well it would run 34-35mph. It was not a performance hull by any means, just a old style 16' "row boat" aluminum hull with heavy 3/4 ply full floor, casting platform, 3 batteries, and a livewell. I'd check for water logged foam, I know this boat had it before I rebuilt it!

 

[sutor623]

Nah, there's no big issues here. Worst case scenario is my tach is reading off. The shop that set this motor up before I bought it put a 15p stock on it and it ran right at that 5800rpm sweet spot. The issue was that instead of getting a new stock prop (because I knew it worked well) I tried to step into more of a performance prop. I fully restored this boat, and the motor is in pristine condition. What were your RPMs when you were running 38MPH? Were you running GPS speed? Either way, thanks for the input. I guess the 4 and 2 strokes run very differently.

 

[anzomcik]

I did not fully read every post so I may have missed this.

Turning point has a prop exchange program, as long as you have your box and the prop that has no wear for $25 you can exchange it for another pitch. It is through the turning point company. I would say it would be in your best interest to look in to that. Check it out on the "support" tab on their website