# Jack plate on a Jon boat???



## ray2 (Apr 13, 2005)

Is there any benefit putting a hydralic jackplate on a aluminum flat bottom boat or any boat for that matter that does not have some sort of tunnel? Is it a waste of time and money? Or, is there something to gain from this?

FE2


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## TooShallow (May 21, 2004)

If your motor is set back far enough from the transom then a lift may help you run a little shallower and increase performance at planing speed. The key is to have the motor back far enough so you can raise it higher than it would be if it was mounted directly on the transom. There won't be any hole shot benefit without a tunnel.


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## Capt. Lowtide (Jun 30, 2004)

Raising an engine on a jack plate will definitely increase your shallow running capability as well as the top end speed due to less drag. The general rule of thumb with a setback mounted on a flat transom non-tunnel boat is to raise the engine 1 inch for every 2 inches of setback. If your boat has sponsons, you may be able to raise the engine even more since some sponson installations funnel water more efficiently toward the prop. 
When raising the engine an anti-cavitation plate and/or additional cupping in the prop may be needed for optimum performance. 

Personally I would believe that a properly adjusted manual jackplate with or without prop work/anti-cav plate can work as good if not better than a hydraulic jackplate. 
By experimenting and setting a manual jackplate for optimum performance you will be less likely to overheat the engine while on plane or burn your prop from additional cavitation. The only draw back that I can think of could be some loss of power while the engine is used in reverse since the prop would be closer to the surface possibly generating more cavitation.
Good luck on tweaking out your boat- Curtiss


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## Stuart (May 21, 2004)

Like Curtiss said, reverse is not good with my manual plate. Much worse than our Flats Cat was with the hyd plate. Otherwise I'm happy with my manual setup. Plus you can get a really decent manual plate for under $300. I will say, that I thought that adjusting my manual plate would be as easy as turning the one bolt in the middle. Wrong, I would have to loosen three bolts on each side and then turn the center bolt. So, my plate stays in one place all the time, amen.


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## ray2 (Apr 13, 2005)

What does hole shot have to do with a tunnel, whether it be a pocket tunnel or full tunnel? Any boat can have a good hole shot if the right prop is used, right? I've had 4 tunnel hulls and what I've come to know is that the tunnel gathers water and allows you to raise your motor higher while running, thus running a little shallower than a fixed motor on a transom. I've also had a couple of flat bottom boats, but the motors were always directly attached to the transoms. I've got a new flat bottom now and a buddy is saying that I ought to think about putting a jack plate on it. I'm trying to figure out if it is worth paying $600-$900 for a jack plate just to gain one or two inches for shallower running. All the flat bottoms that I have had I've mounted the motors myself, with the cavitation plate on the lower unit flush with the bottom of the boat. If I mount a CMC jack plate I can only see maybe gaining an inch at the most maybe 2 of raising the motor while running. Is this thought right or because of the flat bottom I will not gain anything? I understand what Capt Lowtide is saying and that makes sense because I've witnessed the water kick up after it passes past the bottom of the boat. Just wondering if there are any flatbottom boat owners out there that have put a jack plate on their rig and if they think that it is worth it or not. Thanks

FE2


TooShallow said:


> If your motor is set back far enough from the transom then a lift may help you run a little shallower and increase performance at planing speed. The key is to have the motor back far enough so you can raise it higher than it would be if it was mounted directly on the transom. There won't be any hole shot benefit without a tunnel.


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## Capt. Lowtide (Jun 30, 2004)

Capt. Lowtide said:


> Personally I would believe that a properly adjusted manual jackplate with or without prop work/anti-cav plate can work as good if not better than a hydraulic jackplate.


Not sure about the hole shot comment myself.

On the last aluminum boat I purchased several years ago, I had the dealer rig it with a CMC 6" manual jackplate. Immeditately I toyed with the threaded adjustment rod to get it as high as possible without blowing out and settled at 3 inches. A few trips later I added an aluminum Whale-Tail anti-cav plate and was able to raise it an additional 3/4 inch. For about $200 I increased my top end, fuel economy and shallow running capability.


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## TooShallow (May 21, 2004)

Agree. Meant to say _shallow water_ hole shot. Raising the motor on a non-tunnel hull won't improve shallow water hole shot. Then again, it may help a little if you get the motor back far enough. IMO, putting a jack plate on a non-tunnel hull is not a good investment. I think you would be better off investing in fixed trim tabs and a cavitation plate. The trim control should be all you need if you get the motor at the right height.


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## ray2 (Apr 13, 2005)

Opposing views, good, thanks for the info guys. I'll keep checking this thread for more input.


FE2


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## TimOub007 (Jun 10, 2005)

You could get a CMC PT-35, which is a power tilt-n-trim unit with a built in jackplate. Cost is about $400 +/- and will help you in more ways than one.

Here is the site:
http://www.cook-mfg.com/jackplate.html and click on PT-35 on the left hand column if that doesn't take you straight to it.

Just remember that by moving the 100-150 pound motor back 5-6 inches off the transom changes the leverage that weight has on the boat. This will increase your draft at rest by 1/2 inch or more. If you can handle that trade off (which most can) then a jackplate can only help.

Tim


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## Melon (Jun 1, 2004)

My jackplate help out a bunch on my Jon.


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## ray2 (Apr 13, 2005)

If I'm not mistaken that PT-35 is only a tilt and trim unit? I don't believe it is also a jackplate? Melon I was just looking at your pic,,,,,,,,,,does your flat bottom have a tunnel? I can't tell. And how much set back is that?

FE2



TimOub007 said:


> You could get a CMC PT-35, which is a power tilt-n-trim unit with a built in jackplate.


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## Melon (Jun 1, 2004)

Nope! No tunnel. Wished it did sometimes. Was gonna add some float boxes but decided not too. When running choppy stuff it would just limit me even more than I am now. I'm limited on just how shallow I can run. The boat is not a true flatbottom. I believe the pitch is 12 degrees in the V.


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## CentexPW (Jun 22, 2004)

One observation I may interject is. Watch the flex in the transum. This doesnt happen to all be has happened to some. A heavy motor on a setback or jackplate puts some stress on the transum which causes stress cracks in the aluminum. This can be the beginning of some trouble. I would say use a transum saver / motor brace while trailering. Lots of bouncing around going on. But most of all just keep an eye on things.


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## TimOub007 (Jun 10, 2005)

fisheye2 said:


> If I'm not mistaken that PT-35 is only a tilt and trim unit? I don't believe it is also a jackplate?


No it is a jackplate too, just not in the conventional sense. It has a built in 2 inches of lift to it. This is calculated from the 5 1/2 inches of set back it provides to be an optimal running height.

In addition to that, I added some extra mounting holes in mine so that I could fine tune the height just like on a jackplate.

So yes, it is a jackplate as well as a t-n-t unit.
I might be selling mine if you're interested. It is less than a year old, and hasn't been used much. I decided to go a different way on my tunnel hull.

Tim


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## ray2 (Apr 13, 2005)

I stand corrected............... for some reason after looking and reading the CMC, I had in my mind that it was a manual setting or hydralic rig. But I see what your saying now. You raise or lower the whole plate on your transom to adjust. Thanks.


FE2


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