a little slow to plane, but rpm a little high at wot

[92rslt1]

1) Performance issue you are trying to correct.
Slow planing, but once it does the rpm will be a little high at wot.
2) Current prop manufacturer, model, aluminum or stainless as a minimum.
quicksilver 48-13704-23 non mirage
3) Current prop diameter and pitch (required).
23p 14 5/8 3 blade SS
4) Wide open throttle RPM and speed with an average load (very helpful)
trim full down 4800, trim in best plane position 5100 with good water condition. max speed 58mph.
5) Engine/drive make, model, year, and HP
454 Bravo 1 1988 330hp non mag motor max recommended rpm 4600-4800
6) Boat make model, year, length and weight
1988 Glastron gx 239 ultra 23ft weight is 3500 dry

Overall the performance it tolerable, I like the high top speeds, but would like it to plane a little better and would feel safer if the rpm didn't go over 4800. I was thinking of trying a 4 blade 24p, but I dont have experience in prop selection.

 

[Lyle29464]

Re: a little slow to plane, but rpm a little high at wot

Do you trim all the way down starting off then trim up till it rides well? Most larger props will slow down top RPM but at hole shot expense.

I would not worry about it being capable of 300 excess RPM But I would not run it at WOT

 

[92rslt1]

Re: a little slow to plane, but rpm a little high at wot

Do you trim all the way down starting off then trim up till it rides well? Most larger props will slow down top RPM but at hole shot expense.

I would not worry about it being capable of 300 excess RPM But I would not run it at WOT

Yea, I start out with trim full down, once it comes over the hump it takes off and quikly reaches max speed with a little trim raise, but its slugish out of the hole. I think I might have too much weight in the rear or something, that could be the issue.. I have that huge motor, 2 optima batterys and a subwoofer next to the motor.

If you add weight to the front does that sacrafice top speed? I might move the batterys and sub to the front. That would relocate about 200 lbs.

 

[Lyle29464]

Re: a little slow to plane, but rpm a little high at wot

weight fore ward will slow you down. Have you ever looked down into the carb to see when the back half opens? Maybe its late. Also check triming advance.

 

[92rslt1]

Re: a little slow to plane, but rpm a little high at wot

I have never messed with the motor, it runs amazing and I didnt think to check that. I can hear the tone of the engine start to change around 2500 with a load on it. The throttle response is instantaneous .

 

[jestor68]

Re: a little slow to plane, but rpm a little high at wot

For a better hole shot, I suggest you try a 4 blade prop.

You don't have to spend a lot to try one out, since the Solas aluminum 4 blades are just over $100.

 

[Scott Danforth]

Re: a little slow to plane, but rpm a little high at wot

make sure the engine is fully up to snuff. when was the last time the engine was tuned up?

 

[92rslt1]

Re: a little slow to plane, but rpm a little high at wot

Engine is babied. Each fall it gets freshened up before its winter nap. I only use mercruiser fluids and filters and tune up parts.

I will try a 4 blade. I was thinking about adding some trim tabs too

 

[92rslt1]

Re: a little slow to plane, but rpm a little high at wot

So I replaced the hub in the prop and took it out today and it runs great, planes almost instantly and runs great up top. Seems to get the best speed around 3/4 down on the trim gauge, but its really cranking the rpms, 5200 seems to be where it runs WOT. seeing as to how I like to run it fast and the motor isnt a mag motor. I might try a 4 blade 25p and see how it responds. I want to be able to run it for extended periods (10 minutes up the lake) at max speeds, without worry of blowing it up.

Is the general Idea that 4 blades are best for holeshots?
Im also going to add a clamp on hydrofoil to see what that does.