17' Seapro holeshot help

[Robbie F]

Ken,
I'm currently turning a 13.25 X 17 aluminum yamaha prop on my 2004 yamaha 90 2S. Its mounted on the highest hole and I can trim it out to get 38 mph @ 5400 rpm wot,

My issue is that the boat will not get out of the hole and plan off with either rear live well running much less both.

[ken2]

When you try to get on plane with the livewell full, does the motor rev up easily, it just can't get the boat up?

Or is the motor bogging down and struggling to gain RPM ?

[Robbie F]

Ken,
It bogs until I shift some weight forward. I've gone as far as drilling 3/8 ventilation holes which helped get the rpms up, but still not enough to plane off. Although I can reach 5400 rpm trimmed all out, my normal runaround trim gets me 5100 rpm @ 34 mph WOT.

[ken2]

You said it was mounted in the highest hole.

Do you mean the bolt is in the top hole. or the motor is in the highest position?

If the bolt is in the top hole, I'd raise that motor on the transom.

look at this thread and video for height. he tries a couple different heights in the video.
http://www.bandofboaters.com/forum/t...gs-to-look-for

[SeaDawg3]

OP can you post a picture of your engine height/transom mounting?

[Robbie F]

I raised the motor up all the way at the transom. When that didn't fix the problem, I ventilated the prop (revs up to @4000).that helped a little with just me in the boat and one live well going, but add another person or the second well going and it won't plane off. The issue with this boat is that the seat and live wells are at the motor.

[SeaDawg3]

I looked at the performance reports on like model boats and even found one like ours here: http://yamahaoutboards.com/owner-res...letins/archive

just to get an idea of the rpm`s, VS speed for the 90HP 2 stroke Yamaha with the different weights and specs. I found there was one like boat that had the 13 1/2 x 15K Yamaha prop and the specs compared to mine were very similar when I changed from the 17k to the 15K.

I had felt the 90 was lazy for our application with typical load. >>> http://www.bandofboaters.com/forum/t...maha-90-stroke

I`m sure I shouldn`t have an issue when the live well is filled and more gear on board. Your top end numbers looked impressive with the 17K prop and you were trimmed way out, just like ours which is not the way I wanted to run when necc. In the performance testes I read alot where the engine was mounted in the number 2 hole position, just as ours. You`ll probably want to lower your engine when you pick a prop and start the testing again. In our case I see no immediate need to raise the engine with hopes to gain just slightly better mileage. When I get around to it, I`ll probably test a good 16" prop when I decide to go Stainless. But for now the 15K did what I needed for the waters we are in...

good luck and report back what you did/do...

[Robbie F]

Thanks for the info SeaDawg. A 16 pitch would put me in the regular trimmed rpm range but holeshot would still be an issue I believe. Don't want to go down to a 15 for holeshot and give up that much cruising speed. Stiletto makes a four blade, vented 16 pitch that may also be a good match.

[ken2]

if 34 MPH and 5100 RPM is your "normal" trim wide open. I think you could drop down to a 15.
A 15 pitch Powertech NRS3 would hook up strong, and give good holeshot, and you'd still be capable of 34 MPH.
You might actually be able to run a little faster then that, but you might over rev a little bit when you really trim it out.