reverse Jack Plate?

roughshot

Petty Officer 2nd Class
Joined
Jul 14, 2010
Messages
164
I have a 22' starcraft hull with a mariner 150 mounted.
The shaft is a standard shaft of 20" and the cavitation plate is +/- 5" above the keel.
This is a great position when the boat is on plane and running at WOT.
The boat takes off nice as the prop is well in the water with the way the boat sits at rest but half way thru throttling up the prop tends to wash out unless I feather it up and there is no wave on the water.
Is there a jack plate out there that will allow me to lower my motor for take off then allow me to raise it when on plane?
 

rampage11

Cadet
Joined
May 10, 2011
Messages
22
Re: reverse Jack Plate?

any hydraulic jack plate will do that.. plan on spending around a grand for one
 

roughshot

Petty Officer 2nd Class
Joined
Jul 14, 2010
Messages
164
Re: reverse Jack Plate?

any hydraulic jack plate will do that.. plan on spending around a grand for one

Thanks for the quick reply.
What about a manual jack plate or a static plate just to lower the motor all together and leave it maybe 1" or 2" above the keel?

I guess I was under the impression that jack plates started from your standard height and worked up, not down?
 

rampage11

Cadet
Joined
May 10, 2011
Messages
22
Re: reverse Jack Plate?

if u want to move up and down while running a hydraulic plate is a must.. manual is for fine tuning not doing a bunch of moving up and down.. my plate starts with cavitation plate even with bottom of boat then goes up
 

Philster

Captain
Joined
Sep 15, 2009
Messages
3,342
Re: reverse Jack Plate?

A jackplate's lowest starting point will be the lowest height you can get right now. Jackplates don't get you depth; they get you height.
 

tincanman

Petty Officer 1st Class
Joined
Apr 12, 2012
Messages
230
Re: reverse Jack Plate?

so, from what you are saying, you are running a 20" shaft motor on a boat with a 25" transom? If so, a jackplate is not meant to fix that application. You need a xl shaft outboard for that transom. Then if you wish, you can add a hydrolic jackplate if you wan't to be able to control the height of your motor on the fly. Im suprised that you don't get blowout when the water is rough aswell as when you take off.
 

jigngrub

Fleet Admiral
Joined
Mar 19, 2011
Messages
8,155
Re: reverse Jack Plate?

any hydraulic jack plate will do that.. plan on spending around a grand for one

Right!

if u want to move up and down while running a hydraulic plate is a must.. manual is for fine tuning not doing a bunch of moving up and down.. my plate starts with cavitation plate even with bottom of boat then goes up

Right!

A jackplate's lowest starting point will be the lowest height you can get right now. Jackplates don't get you depth; they get you height.

Wrong.

so, from what you are saying, you are running a 20" shaft motor on a boat with a 25" transom? If so, a jackplate is not meant to fix that application. You need a xl shaft outboard for that transom. Then if you wish, you can add a hydrolic jackplate if you wan't to be able to control the height of your motor on the fly. Im suprised that you don't get blowout when the water is rough aswell as when you take off.

Wrong.
 

NSBCraig

Lieutenant Commander
Joined
Aug 21, 2007
Messages
1,907
Re: reverse Jack Plate?

Philster is right, jack plates are made to lift (jack) the motor not lower it.

and...

Tincanman is too, your problem is you have the wrong motor on your boat.


You can fix it one of five ways- you can find a different lower end that is the right size for your boat, you can get the right sized motor, you can try to fabricate a a set back bracket that will work and not bind everything up when you tilt , you can get a jackplate and install it into new holes lower on the transom which may let you tilt if you lift it first or you could cut your transom down.

Personally I'd start with trying to get the right sized lower end for your boat.

I'm not sure what the point of the above post was except to point out how the poster doesn't know about the subject, while offering zero help or advice. A jackplate's mounting holes when lowered is at the exact same height as the mounting holes on your transom, it's not possible for it to work the other way.
 

roughshot

Petty Officer 2nd Class
Joined
Jul 14, 2010
Messages
164
Re: reverse Jack Plate?

Right!



Right!



Wrong.



Wrong.

THanks JIGNGRUB for clearing that up.

I do get some blowout when the water is rough, like it was this morning on lake michigan, but when its that rough, I don't need to go more than 12 mph anyways.
Picked up a smaller pitch prop this morning from my mechanic to test tomorrow morning to see if it helps with some of the problem. But still going to keep an eye out for a jack plate to get me down 5" during take off and raise it up when on plane.
Any recommendations on brand or style?
 

roughshot

Petty Officer 2nd Class
Joined
Jul 14, 2010
Messages
164
Re: reverse Jack Plate?

Philster is right, jack plates are made to lift (jack) the motor not lower it.

and...

Tincanman is too, your problem is you have the wrong motor on your boat.


You can fix it one of five ways- you can find a different lower end that is the right size for your boat, you can get the right sized motor, you can try to fabricate a a set back bracket that will work and not bind everything up when you tilt , you can get a jackplate and install it into new holes lower on the transom which may let you tilt if you lift it first or you could cut your transom down.

Personally I'd start with trying to get the right sized lower end for your boat.

I'm not sure what the point of the above post was except to point out how the poster doesn't know about the subject, while offering zero help or advice. A jackplate's mounting holes when lowered is at the exact same height as the mounting holes on your transom, it's not possible for it to work the other way.

Thanks.
Ya, the motor was a buddy deal and afforded me a newer motor than what I had, went from a '79 to a '97.
The motor performs great at take off and after on plane, its just that in between spot in the throttle up that I need to get rid of.
 

jigngrub

Fleet Admiral
Joined
Mar 19, 2011
Messages
8,155
Re: reverse Jack Plate?

Whether your jack plate goes up or down depends on where you mount it on the transom.

If you mount your plate on the transom so that the motor is where it is now on the transom in the full up position you'll be able to let it down for take off and then gradually lift it for optimum performance.

Jack plates work well on most remote steer boats... but ain't too sporty on a tiller with too short of a shaft, but they'll work ok on a long shaft tiller with a short transom.
 

NSBCraig

Lieutenant Commander
Joined
Aug 21, 2007
Messages
1,907
Re: reverse Jack Plate?

So your going to spend around $1,000 and drill new holes into your transom 5" lower than the stock setup?
 

roughshot

Petty Officer 2nd Class
Joined
Jul 14, 2010
Messages
164
Re: reverse Jack Plate?

So your going to spend around $1,000 and drill new holes into your transom 5" lower than the stock setup?
Actually I was able to eliminate the issue when I went down a couple prop sized. First tested a 17p no problem but lost a little speed and would rev a little too high. So I went up to a 19p SS prop and found my sweet spot. Great holeshot, great low RPM cruising with 4500 rpm I am cruising at 30 - 32 mph depending on water conditions and a WOT of 5700 and a top speed of 40+ mph.
 

Mr. Demeanor

iboats.com Partner
Joined
Mar 6, 2006
Messages
55
Re: reverse Jack Plate?

What prop are you running? If its not blowing out too bad, a prop with a lot of bite might make it work just fine. Something like a Mercury Revolution 4. They actually run quite well even partially surfaced.
 

NSBCraig

Lieutenant Commander
Joined
Aug 21, 2007
Messages
1,907
Re: reverse Jack Plate?

Cool, good to hear it all got worked out.
 
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