A little help please

[olddog29]

I'm nearly complete in putting an abused 2001 Glastron SX 170 with a what I believe is a (1998 115 Evenrude (13-spline) w/20" foot) back to as right as I can get it. The motor has a very beat up 14 X 17 three bladed aluminum prop which at WOT reaches only about 5200 and 36 indicated. There is not really a hole shot, which I would like to pull up ski / waveboarders. The boat would not plane till about 20 indicated until I recently added an SE 300, which helped immensely. I've got compression ranging from 115 to 110, everything is firing, and when planed, will all but kill any tuber I pull. That said, I've got two questions:
1. Would anyone recommend a replacement prop as it is time?
2. Will pulling tubers, skiers, or waveboarders at less than WOT cause damage to the engine?

Thank you!

 

[SkiDad]

17p seems right for your setup - if your prop is pretty beat up you will be surprised how much better a new one pulls - doesn't take much blade damage to loose thrust. Do get a new prop...i would think you would be happy with a 13.25x17 - that will get your rpm up a little and help hole shot - maybe the 3rd prop here: http://boatpropellers.iboats.com/Ev...17.00&chart=18&engine_id=87&cart_id=017975453

make sure you get the correct thrust washer, etc - call iboats and they will hook you up based on the numbers on your current prop - you might have the 4th prop, i dunno

as long as your engine can hit 5000-5500 at WOT it doesn't matter what rpm you run it at for tubing and cruising.

 

[Starcraft5834]

Def get a new prop...pulling skiers and boards is hard on any engine...prop it right and your ok...

 

[olddog29]

In regards to the primary mission of this boat, that would be pulling skiers, waveboard, and tubes, would going up to a four blade be beneficial? I'd assume that this would create more bite but cost some top end, which would be fine. However, I'm concerned after reading some post here that this might also hamper WOT and I fully understand what happens when one assumes. Thank you all for your responses!

 

[SkiDad]

if you are pulling skiers with 2 skis on - a 17p would still be great. If you have a heavy slalom skier than you might consider a 15p 4 blade.

 

[olddog29]

According to the Iboat info you were kind enough to include, a 15p 4 blade solas is available. My question is other than putting it on and trying it out, is there a calculation that will give me a rough idea of the effect I might see in dropping 2 degrees of pitch, which as I understand should increase WOT by about 400 and dropping 1 inch in diameter, which as I understand will again increase WOT, but adding a 4th blade, which should decrease WOT - will result with a base of 5200 take from a 14 X 17 3 bladed prop that has absolutely no edge to cut through the water? Nothing like asking for the impossible.
Thank you mitzysman!

 

[Starcraft5834]

assuming your currently in the recommended WOT rpm range with your 3 blade,, if you get a 4 blade, drop down (1) in pitch and your good... if your going to haul folks mostly, a 4 blade is best choice there for sure

 

[olddog29]

Well alrightythen, I'm going to give a Solas Rubic 13X15 a go. Fingers crossed!
Thanks again!