Help me get my outboard right height please!

little.boat

Seaman
Joined
Mar 25, 2013
Messages
73
Ok I have a new to me boat. Today is the first day I got to run the boat. Please read all as I will first tell my problem and then give my current measurements.

When end I would take off and get up on plane the boat would bounce up and down, not chine walking but more like trying to ride a bull. It did this whether the motor was trimmed up or down. Worst when trimmed up. It does this whether there is one person or 2 in the boat. However if 2 of us were in the boat and one of us sat in the drivers seat, of course and the other sat up near the bow the boat would get up and run without the bouncing. Now I could add weight to the bow and fix this bit I know that is just covering up the real problem so I'm looking at how the motor is set up.

the boat is a 1983 Bullet 19VEE with a 1984 200hp mercury V6 on it. The hull is a stepped hull and all measurements are taken from the bottom of the bottom step, lowest point of the boat. The boat is level on the trailer and motor was trimmed until the cavitation plate was level. The boat also has a 5" jack plate.

bottom of the boat is 16 1/4" off garage floor so this is our base point.
The cavitation plate is 24" off the garage floor.
The center of the prop shaft is 15 3/4" off the garage floor.

that makes my cavitation plate 7 3/4" above the bottom of the boat.
that makes my prop 1/2" below the bottom of the boat.

I'm thinking my motor is set to high and needs to be lowered. However I don't know enough about these fast bass boats to start messing with it without some opinions, my biggest motor before was a 90hp. Do you guys think my motor is set to high and are my symptoms the result of a motor being set to high.
 

blackhawk180

Petty Officer 1st Class
Joined
Jun 14, 2012
Messages
367
Re: Help me get my outboard right height please!

PICS are almost mandatory here.... and would help us help you!
 

MH Hawker

Vice Admiral
Joined
Jul 13, 2011
Messages
5,516
Re: Help me get my outboard right height please!

Normally the cav plate is level with the bottom of the boat.
 

JB

Honorary Moderator Emeritus
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Mar 25, 2001
Messages
45,907
Re: Help me get my outboard right height please!

Move it down until it stops porpoising.
 

H20Rat

Vice Admiral
Joined
Mar 8, 2009
Messages
5,204
Re: Help me get my outboard right height please!

Don't go moving it until you confirm it is too high! Especially with a jack plate, the further you move the lower unit from the end of the hull, the higher it can go.
 

dan02gt

Chief Petty Officer
Joined
Aug 30, 2012
Messages
463
Re: Help me get my outboard right height please!

Huh? You think being back 5" makes a huge difference?

Typically 1/4" rise in the water column for every 1" of setback. So it can make a big difference.

little.boat

A Bullet is a ultra performance hull and has to be treated as such. Things that work on bowriders, center consoles, and other bass boats will not work on a Bullet. Putting anti-cavitation plate even with pad will be way to low for this hull. Based on where guys run modern Bullets 1/2" below the pad is not that far off, but if you want to try it lower drop it no lower than 3.5" below the pad, test, adjust, and test some more.

I would also really recommend asking the question here:

Bullet Boats

Due to the age of the hull one other thing to check would how level the running surface of the hull is. The last 5-6' should be level with no hook or rocker.
 

H20Rat

Vice Admiral
Joined
Mar 8, 2009
Messages
5,204
Re: Help me get my outboard right height please!

Huh? You think being back 5" makes a huge difference?


Depends on the speed of the boat, but if you are traveling at 20 mph, it can make a huge difference!
 

little.boat

Seaman
Joined
Mar 25, 2013
Messages
73
Re: Help me get my outboard right height please!

Depends on the speed of the boat, but if you are traveling at 20 mph, it can make a huge difference!

I'm looking to travel 70+ mph. I also posted this on bass boat central and like someone else said I can't put the cavitation plate that low if I do it will kill my speed creating too much drag in the water. I'm going to drop the prop 3.5" below and then start moving the jackplate up 1/2" until I max out my rpm's and top speed.
 

little.boat

Seaman
Joined
Mar 25, 2013
Messages
73
Re: Help me get my outboard right height please!

Typically 1/4" rise in the water column for every 1" of setback. So it can make a big difference.

little.boat

A Bullet is a ultra performance hull and has to be treated as such. Things that work on bowriders, center consoles, and other bass boats will not work on a Bullet. Putting anti-cavitation plate even with pad will be way to low for this hull. Based on where guys run modern Bullets 1/2" below the pad is not that far off, but if you want to try it lower drop it no lower than 3.5" below the pad, test, adjust, and test some more.

Some do run them that high some even run them as high a 1.5" above the pad however most of those setup appear to have 10-12" jackplates and those sporty or coned l/u.
 

V153

Lieutenant Commander
Joined
Apr 16, 2011
Messages
1,764
Re: Help me get my outboard right height please!

Sounds to me like yer just a tad too high. Go down a lil'n see what happens. What kinda prop'r ya runnin?
 

dan02gt

Chief Petty Officer
Joined
Aug 30, 2012
Messages
463
Re: Help me get my outboard right height please!

Typically 1/4" rise in the water column for every 1" of setback. So it can make a big difference.

little.boat

A Bullet is a ultra performance hull and has to be treated as such. Things that work on bowriders, center consoles, and other bass boats will not work on a Bullet. Putting anti-cavitation plate even with pad will be way to low for this hull. Based on where guys run modern Bullets 1/2" below the pad is not that far off, but if you want to try it lower drop it no lower than 3.5" below the pad, test, adjust, and test some more.

Some do run them that high some even run them as high a 1.5" above the pad however most of those setup appear to have 10-12" jackplates and those sporty or coned l/u.

Yep you're not going to be able to run 1.5" above the pad with 5" of setback and the stock lower unit. What prop are you running?

You should definitely be able to get 70 out of that setup
 

little.boat

Seaman
Joined
Mar 25, 2013
Messages
73
Re: Help me get my outboard right height please!

25pitch 4blade not sure of the brand it isn't stamped.
 

little.boat

Seaman
Joined
Mar 25, 2013
Messages
73
Re: Help me get my outboard right height please!

Another question I have is after looking at it today that if I lower my moth or that far the exhaust holes will either be in the water or right at the waterline. If this is the case I am worried that after a fast run when I start slowing down water will rush into the exhaust holes and up into the powerhead. Is this a actual concern or am I being paranoid?
 

dan02gt

Chief Petty Officer
Joined
Aug 30, 2012
Messages
463
Re: Help me get my outboard right height please!

Another question I have is after looking at it today that if I lower my moth or that far the exhaust holes will either be in the water or right at the waterline. If this is the case I am worried that after a fast run when I start slowing down water will rush into the exhaust holes and up into the powerhead. Is this a actual concern or am I being paranoid?

The exhaust relief port shouldn't have a problem with backwash coming off plane, but if it is submerged all the time that will be a issue. The boat would run rough idling and have no hole shot.
 

little.boat

Seaman
Joined
Mar 25, 2013
Messages
73
Re: Help me get my outboard right height please!

The exhaust relief port shouldn't have a problem with backwash coming off plane, but if it is submerged all the time that will be a issue. The boat would run rough idling and have no hole shot.

Do they make something I could install to I guess reroute the exhaust or something? What would be the fix for this if it is the case? I'm not for certain that it will be but I remember thanking the exhaust was close to the water but I don't remember how much room I had. Unfortunately it's like 13 deg today and don't look to get warm for a few weeks so if there is something I can add to the motor I would probably go on and do it just for piece of mind but if not I guess I'll just have to drop it and wait and see.
 

dan02gt

Chief Petty Officer
Joined
Aug 30, 2012
Messages
463
Re: Help me get my outboard right height please!

I'm not aware of a kit or anything to change where the port exits the motor, but on my Optimax 150 the port was just a high temp molded rubber hose so it may be possible to extend it higher up on cowling. It would be a good project for sure. The other thing people do is stick volley balls or basket balls in their jack plates to give the stern more flotation.
 

little.boat

Seaman
Joined
Mar 25, 2013
Messages
73
Re: Help me get my outboard right height please!

I'm not aware of a kit or anything to change where the port exits the motor, but on my Optimax 150 the port was just a high temp molded rubber hose so it may be possible to extend it higher up on cowling. It would be a good project for sure. The other thing people do is stick volley balls or basket balls in their jack plates to give the stern more flotation.

Might have to try that.
 
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