how can i keep the prop in the water

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Loggerhead Mike

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My props bad to blow out water or just spin when I turn or hammer down to hard without the motor trimmed all the way down. I'm usually turning around 5k, its a 50hp jonnyrude 89 modle. THe cat plate is about level with the bottom of the boat.


Do yall think this is a prop or height problem?
Apreciate any openions
 
You don't have spun hub on your prop by chance do you? Worth checking out before you start adjusting other stuff.
 
No that was the first I checked. It seems like the props to high or just gets in dirty water and can't get a grip if ya know what I mean
 
Loggerhead Mike said:
No that was the first I checked. It seems like the props to high or just gets in dirty water and can't get a grip if ya know what I mean
These would be my guesses as well.
How the hull before the prop,dents,dings etc.
I read somewhere,that if you were to run a thick bead of silicon/caulking(1/2"),sideways on the hull(stern),before the prop alot of smaller jon boats wouldn't plane.I guy did this as a trick to his buddies boat.Although this is neat,I don't think it's your issue.
Have you tried to lower your outboard a bit?
I run a tunnel hull so I can bring my outboard up alot.I run into the same problem as you if I go to high though.
For me even a 1/4" in lowering helps.
This outboard wasn't drilled through the hull though so it was an easy fix.
 
The motor is as low as it will go. I'm debating on getting a jack plate just wanted to see if anybody else has had the same problem.

Thanks for yalls opinions
 
It certainly sounds like it could be a height problem, but would re-measure your cav plate height. Eyeballing can be deceptive. Run a yard stick along the centerline of the bottom of the hull and extend out to cav plate. Put the motor in the trim position that makes the cav plate parrellel to the yard stick. Measure the above or below distance. Another set of hands will help.

Is your basstracker flat, mod-v, or v at the transom?

Is it happening just on sharp turns? and turning in both directions?

When you say hammer down, is this when you are already on plane or on launch only? Does it happen in calm/flat water?

What kind of speed are you going when you get the blow-out?

Is this 50hp at the boat max recommended hp or higher?


If it is a height problem, there are prop designs that can handle that better than stock, but they might not be available on smallish outboards. I believe, but would have to check, they have more rake, and do not provide as much lift as stock props.

Hull disturbance can cause this, as was already mentioned. Any weeds or crap on lower unit/prop will cause it. You hadn't mentioned anything about the hull or prop condition.
 
what kinda prop is it . stainless or aluminum . new, old, beat up props can cause all kind on problems stainless .you can cup the leading edge a little to make it hold onto the water if you cup that edge to much it will affect top end , there;s a fineline . aluminum . ya get what ya get . i have to tuck my 40 in to get a holeshot or it blows out .. then trim out as i'm running . i would also check the bottom just to see if someone didn't put a live well drain or a patch under there .
 
Thanks for the help fellers. It tends to blow the most turning either direction if I don't back off the throttle and on the holeshot if not trimmed.all the way down.

The hull and prop are good. I put the first scratch on the stock prop last wknd, not to bad for a 22 y-o motor
 

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Loggerhead Mike said:
Thanks for the help fellers. It tends to blow the most turning either direction if I don't back off the throttle

If the cav plate is above the bottom, that can be a common thing to happen on sharp turns.

and on the holeshot if not trimmed.all the way down.

I assume you don't have power trim. How does your boat sit in the water before takeoff, length level wise with people and gear when this occurs? Moving some weight toward the transom may help this.

The hull and prop are good. I put the first scratch on the stock prop last wknd, not to bad for a 22 y-o motor

Need to measure to see where you are really at. If you are already an inch below, further lowering can start to impact top speed. A jackplate should help, just make sure you have adjustment range to test at various heights. You don't want to go any lower than you have to.

PS: That is a mod-v
 
Unless I missed it somewher in the posts there is no mention of the location of the cavitation plate relative to the water when the boat is underway. On plane, the cavitation plate should be no more than a half inch above to a half inch below the water that is flowing around it. The relation of the cavitation plate to the bottom of the hull has little to do with the correct motor height set-up.

Get that sucker up on plane in flat water and stick your head back there to see where the cavitation plate is riding. If it is too high or too low it can cause the problems you are experiencing.

Too High = prop comes partially out of the water during a turn and cavitates

Too Low = areated water gets sucked into the prop and it cavitates.
 
Good deal budys!

Cat plate seemed to be about a half to an inch out of the water on flat plane. I'll find out for sure this weekend.

It does have elect. Trim and the way these rigs are set up you have no choice but to put all three batterys and the rest of the heavy stuff in the back

Any ideas on a good jack plate? The one I've been looking at have a 6inch setback and I believe 4 in of vertical adjustment for 400.

Really appreciate yalls time
 
Loggerhead Mike said:
Good deal budys!

Cat plate seemed to be about a half to an inch out of the water on flat plane. I'll find out for sure this weekend.

OK, that does sound like it is high enough to cause the problem. Still measure to compare.

It does have elect. Trim and the way these rigs are set up you have no choice but to put all three batterys and the rest of the heavy stuff in the back

So, I assume that means the waterline is half way up your transom. Having elec trim should make launching a non-issue. Trim all the way in for launch, once on plane trim out for speed. Trim in some before making sharp turns.

Any ideas on a good jack plate? The one I've been looking at have a 6inch setback and I believe 4 in of vertical adjustment for 400.

For that kind of money, with the additional weight, would think long and hard if I could live with the trim adjusting. Even so, given you have the power trim, a fixed jack plate would probably suffice. Just have to find the sweet spot.

Really appreciate yalls time

See my comments above.
 
I see what you are looking at flatboat...it looks like the keel strake has a rough edge or a chunk taken out of it.

If that is making "dirty water" that could be all of the problem.
 

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