New Prop - Hole Shot Optimization

[PBRman]

1) Optimize hole shot.
2) Current prop manufacturer (unknown), model (unknown), stainless .
3) Current prop diameter and pitch: unknown, bought boat used, there don't appear to be any markings, three blade.
4) Wide open throttle RPM and speed with an average load: 4500-4800, 30mph-ish
5) Engine/drive make, model, year, and HP: Merc 3.0 1993, 135hp
6) Boat make model, year, length and weight: Glasstream Cutlass 172, 1993, 17ft, not light.

So I've needed a new prop for awhile since the old one was missing little chunks and minimally bent, but yesterday kind of secured the deal. I had my girlfriend drive the boat onto the trailer, told her to trim it, she did, but didn't trailer trim it...:facepalm: So what prop should I get to optimize hole shot? We don't really have to worry about rocks (though I guess boat ramps do kind of count). From what I've read on here the pointers appear to be towards a 19 pitch. Good idea? The boat is heavy enough that I don't have a great high-end speed (low 30s), though some of that could've been the old prop, and the fact that the throttle is poorly tuned. We pretty much only use the boat for waterskiing so I don't need anything special for cruising, trawling etc...

Thanks!

 

[SparkieBoat]

Re: New Prop - Hole Shot Optimization

well you have a lot of guessing to be done, with out more specific info it is impossible to do anything but guess. the most important is to know current prop pitch, remove the prop and look for some numbers on the back of the hub. a more exact WOT RPM number would be helpful along with GPS speed at WOT. I think high 4k rpms is about the right range for that motor. do a little research and find out the recommended RPM range and prop for the upper end of that range. but my wild guess is that a 17 or 19 would be about right. If you could borrow a prop and do some test it would be helpful. your old prop having some chips/dents probably hurt performance some. you also may consider trim tabs if you want a better hole shot.

 

[PBRman]

Re: New Prop - Hole Shot Optimization

well you have a lot of guessing to be done, with out more specific info it is impossible to do anything but guess. the most important is to know current prop pitch, remove the prop and look for some numbers on the back of the hub. a more exact WOT RPM number would be helpful along with GPS speed at WOT. I think high 4k rpms is about the right range for that motor. do a little research and find out the recommended RPM range and prop for the upper end of that range. but my wild guess is that a 17 or 19 would be about right. If you could borrow a prop and do some test it would be helpful. your old prop having some chips/dents probably hurt performance some. you also may consider trim tabs if you want a better hole shot.

Thank you. I'll go home and remove it at lunch. It's not going to be possible to get the GPS or WOT RPM since I don't have a prop right now (or a gps).

Do trim tabs make a noticeable difference? They seem pricey for what they are.

 

[SparkieBoat]

Re: New Prop - Hole Shot Optimization

they are around $500-600, not much more than a new SS prop, but yes trim tabs do make a big difference. they should be installed on every boat over 17' from the factory. let me know the pitch of your old prop and what the RPM range of your motor is.

 

[90stingray]

Re: New Prop - Hole Shot Optimization

There are some $150 smart trim tabs... they don't have to be the $500 ones. Anyhow, if you want a better holeshot I would for sure look at a 4 blade prop. Prolly 17 pitch. These can be found new for around $100. Goodluck!