# To Jackplate or not to Jackplate, Classic.



## Jeremy_James (Feb 27, 2013)

I have a 2008 Classic with a poling platform and a Suzuki 15hp 4 stroke (97lbs) tiller. No batteries. No electronics. 6gal tank up front under front removable casting deck. I try to keep it as light as possible for that I pole the skinniest waters I can find. That being said, my motor without a Jackplate takes a significant amount of water to run/hole shot @ approx 12" +/-.

I know the pros of a Jackplate, but the cons are worrying me. That's why I am turning to you guys for some experience and advice. 

I am afraid that if I put a Jackplate in the back and setback my motor 4-5" further back that my Gheenoe will be too ass-end heavy and squat while poling thus, being a bigger disadvantage than an advantage. However, maybe I am over thinking the Jackplate and it would 100% be worth it. The bobs mini is 12lbs. 

All of your input and help will be greatly appreciated! I can't make this decision on my own ;D


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## paint it black (Nov 3, 2007)

I sold my Classic to a friend. he put a home made jack plate on it and loved it. Still poles super shallow. He has a 18HP Nissan on it.


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## anytide (Jul 30, 2009)

if it will holeshot from 12" of water- leave it alone... maybe raise it a little and add a custom prop.
---if your operating in 12" your already propping the bottom....


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## DuckNut (Apr 3, 2009)

Measure from the cavitation plate to the bottom of the skeg...that is about how shallow you can run no matter how many gadgets you bolt on.

But if you are running full speed in less than 12" then you are tearing up the bottom with prop wash.


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## Jeremy_James (Feb 27, 2013)

I have never broke out a ruler and measured my exact running depth. I am estimating the depth. The measurement from my cavitation plate to the bottom of my skeg is dead on 11". 

Even with that being said, if the motor is set back 5" can't the motor come up at least 2"?


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## anytide (Jul 30, 2009)

wheres the cav. plate in relation to hull bottom? 1" below the hull in common rule, but with the right prop and fin you can sneak it up a little....
--the further back you set the motor the more you can raise it -sometimes....
--sounds like it works great the way you have it.


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## Jeremy_James (Feb 27, 2013)

The vibe that I am getting is, it ain't worth getting a jackplate..


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## fultonswimmer (Apr 14, 2010)

I think, but no expert, that you would gain a whole 2-3" of running skinny ability with a jp. Poling or paddling sounds like you already have a good system.


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## Brett (Jul 16, 2008)

Even with 36 inches of setback, you only gain 1 inch of difference in actual running depth.
I've done the math to prove it myself more than once. Only way to do better is to install
a cleaver prop, power jackplate, a nosecone with low water pickup and to
also install power trim tabs. Nay say all ya' want, but it's a fact, not fiction guys.
Then y'er gonna need beaucoup horsepower to make it work :-[

previous post, see the diagrams and math at the bottom of the page

http://www.microskiff.com/cgi-bin/yabb2/YaBB.pl?num=1355701068/5


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## Jeremy_James (Feb 27, 2013)

> Even with 36 inches of setback, you only gain 1 inch of difference in actual running depth.
> I've done the math to prove it myself more than once. Only way to do better is to install
> a cleaver prop, power jackplate, a nosecone with low water pickup and to
> also install power trim tabs. Nay say all ya' want, but it's a fact, not fiction guys.
> ...



Brett,
Interesting read. Thank you. So with my set up, am I basically stuck with what I've got, without the ability to make any improvements to run skinnier? My Suzuki has a high water pick up, which is located underneath the cav plate, another disadvantage.


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## Marshfly (Nov 4, 2012)

> Even with 36 inches of setback, you only gain 1 inch of difference in actual running depth.
> I've done the math to prove it myself more than once. Only way to do better is to install
> a cleaver prop, power jackplate, a nosecone with low water pickup and to
> also install power trim tabs. Nay say all ya' want, but it's a fact, not fiction guys.
> ...


Your diagrams leave out a very important fact. That water coming off of the transom will want to return to level as it leaves the transom. As you get further from the transom, the water level is higher and higher until it reaches the static water level of the body of water you're running in. I can run my Caimen with no tunnel and a Microjacker at full height and keep 18-20psi of water pressure at all speeds. Just now, I went to look at the position of the nosecone in relation to the hull bottom with the engine jacked up all the way. It's about 3" below the bottom. So, almost half of my prop is above the bottom of the boat. Next time I run, I need to get a pick of the position of the cav plate above the water and the motor height in relation to the transom.


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## Capnredfish (Feb 1, 2012)

Just want to add to this. It is not only how much lower unit, prop or nose cane is below the hull bottom. I doubt any of these skiffs ride with the hull out of the water. So if you can find a way to measure that you would know the running depth. As far as prop wash I bet it is more than a foot , probably close to 3 ft but does little harm at that depth.


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## Brett (Jul 16, 2008)

> That water coming off of the transom will want to return to level as it leaves the transom.


True...but lidar scanning of the wake surface actually shows that the wake surface continues to drop
before starting to rise back up again. That point of rise isn't until well past the rear of the prop blades.
at typical planing speeds. I didn't believe it either, but the hydrodynamics are what they are
and the lidar scans prove it. That's the reason mud motors like the beavertail put the blade back
where the wake comes back together at the point of the vee.

Previous post from when I was trying to make sense of wake dynamics:

http://www.microskiff.com/cgi-bin/yabb2/YaBB.pl?num=1338040322/0


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## AfterHours2 (Aug 2, 2010)

If you want something to just raise the motor a few inches then either build a riser or shim the motor. The only jackplate I would own to this day would be either hydraulic or electric. To myself, a manual style is just plain useless..


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## cutrunner (Jun 8, 2010)

> If you want something to just raise the motor a few inches then either build a riser or shim the motor. The only jackplate I would own to this day would be either hydraulic or electric. To myself, a manual style is just plain useless..


This plus everything Brett said.
Small skiffs don't throw water up after it leaves the transom like a full size flats or bay boat does.
I've installed hundreds of jackplates on flats and bay boats and when I out one on my skiff I went by the same 6in setback =2 inch raise.
Wouldn't even get on plane with a nice cupped stainless prop... I couldn't believe it..

If its that big of a deal you could have a full sizel tunnel put in it for the cost of a decent power jackplate.
Most every skiff that has a tunnel installed after the fact usually has some kind of fault but in a gheenoee with a 9.9 or 15 your not a speed demon and I really don't see making anything worse. (Not that there's anything wrong with your setup).
The big faults seen in "after the fact tunnels" are in larger more higher performance boats than gheenoees


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## Vertigo (Jun 3, 2012)

> Measure from the cavitation plate to the bottom of the skeg...that is about how shallow you can run no matter how many gadgets you bolt on.


I don't think this statement is necessarily true. A hull, running on plane creates a wave that it rides on. Depending on the hull shape and boat speed, that wave may actually lift the boat above the static water surface a few inches. This phenomena explains how some tunnel hulls can actually plane over water depths that are less than the amount of prop and skeg that protrude below the bottom of the boat.


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## Brett (Jul 16, 2008)

> A hull, running on plane creates a wave that it rides on.


Is this the "shallow water effect" caused by the fact that water doesn't compress?
The water becomes trapped between the hull and the bottom creating greater lift
than the same hull running in deeper water?  :-? I've been reading again....


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## Vertigo (Jun 3, 2012)

I think the "shallow water effect" amplifies the wave under a planing hull, possibly raising the boat even higher above the static water level. OTOH, I wouldn't gamble on getting those few extra inches of clearance unless I was very sure of my boat and the ability to stay on plane. A wrong decision could result in a long drag through the mud or else a long wait for high tide.


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## Creek Runner (Sep 1, 2011)

> > A hull, running on plane creates a wave that it rides on.
> 
> 
> Is this the "shallow water effect" caused by the fact that water doesn't compress?
> ...


 [smiley=1-computergeek.gif]

[smiley=popcorn2.gif]


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## flyfshrmn82 (Oct 12, 2007)

If you want to get the transom up, then you need to get the bow down. I think a "seat extention" of some sort would help with this. Get one of your 200+lb buddies to sit in a chair that extends about 3' off the front of the boat.


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## jking (Aug 11, 2011)

Is the water pickup still under the cav plate only on an '08? My DF15 is older ('97) and only picks up water from there. If so the effect on the water pickup of lifting the motor should be considered.

You get up on a poling platform, say a Gheenoe factory one, you're weight is already way back there, don't know if putting a jack plate is going have much negative effect on depth moving weight to stern 4" since you have that much weight rearward already when poling.

I have the same boat and motor, considered it for running some longer shallow areas like the Chassohowitska on a negative tide trying to get back to the ramp, something like that, but not sure it's worth it for what you're asking. Maybe idle in slow on a big flat to get further in but that's all I can see.

Running you can move forward and will get some extra depth with it. But on install have to adjust so you don't get blowout on the turns, maybe ad an anti cav plate, etc. It's a cost/benefit question.


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## Marshfly (Nov 4, 2012)

You guys are way over thinking this. In my eyes, a jackplate isn't used to "setback" the motor. It's used to raise the motor to take advantage of the enhanced grip characteristics of a heavy cup prop. With my prop/jackplate combo, I can't get max rpm without having the JP almost all of the way up. The prop simply has too much grip to allow it with the horsepower that I have. That increased grip combined with the props ability to not blow out while having the upper surface of the blades above the surface of the water is what allows me to raise the motor giving me less draft. The jackplate allows me to raise the motor substantially higher than I would if it were simply bolted to the transom. 

Setback doesn't even come into play.

And that's the facts, Jack.


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## DuckNut (Apr 3, 2009)

> > Measure from the cavitation plate to the bottom of the skeg...that is about how shallow you can run no matter how many gadgets you bolt on.
> 
> 
> I don't think this statement is necessarily true.  A hull, running on plane creates a wave that it rides on.  Depending on the hull shape and boat speed, that wave may actually lift the boat above the static water surface a few inches.  This phenomena explains how some tunnel hulls can actually plane over water depths that are less than the amount of prop and skeg that protrude below the bottom of the boat.


You may be right Vertigo...my statement was not meant to be all encompassing...however most boats ride deeper while under power than they are at rest. Very few boats have a hull that creates enough lift to rise them without tremendous horsepower.

If I am not mistaking, the owner of the Grass Slipper found this out.

However, if you read my post and look at it in the most simple context if the cavitation plate is at the bottom of the boat and the plate is at the waterline at rest, then the hull is just touching the water.

At speed the displacement of the hull creates a pocket which, when looking back makes it appear that the cavitation plate is at the surface, when in fact it is below static surface.


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## el9surf (Dec 23, 2008)

Last time I posted on this I got three pages woth of people ranting about how I'm going to tear up the flats. This without knowing I'm one of the most environmentally concious anglers around. Funny how you have two pages worth of decent feedback. Glad you are getting positive feedback. Post this next week and you might get torn apart by the internet mob


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## anytide (Jul 30, 2009)

> Last time I posted on this I got three pages woth of people ranting about how I'm going to tear up the flats. This without knowing I'm one of the most environmentally concious anglers around. Funny how you have two pages worth of decent feedback. Glad you are getting positive feedback. Post this next week and you might get torn apart by the internet mob



.............wait for it.


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## Marshfly (Nov 4, 2012)

> > Last time I posted on this I got three pages woth of people ranting about how I'm going to tear up the flats. This without knowing I'm one of the most environmentally concious anglers around. Funny how you have two pages worth of decent feedback. Glad you are getting positive feedback. Post this next week and you might get torn apart by the internet mob
> 
> 
> 
> .............wait for it.


I'm waiting for the day that I get that lecture, fishing in the land of winters cold enough to kill off every bit of grass yearly and nothing but soft mud bottoms. :


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## goon squad (Jun 5, 2013)

Here's a plate I built for my Noe. It was manually adjustable with only 1/2" set back. It worked great, weighed very little and with 1/2" set back there was no extra weight on transom. I have a new 15'4" Highsider  that I am currently designing a plate that is pretty much the same only this one will have a lenco actuator mounted on the inside of the transom to give me 4 1/4" of lift. I have found out from the fist one is that once you find the correct height for your set up you should set it and forget it, but it will be nice to be able to raise the motor vertically in a off plane situation. I'm sure everyone that has used shallow water drive on small outboards knows what happens when you hit the throttle.The stern goes down and the water goes up.


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## Marshfly (Nov 4, 2012)

Very trick piece Skeeter.
Careful or you'll have 20 private messages from people wanting to order one.


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## Brett (Jul 16, 2008)

Is that an optical illusion, or is that outboard tucked so far in, that the lift provided
by the jackplate has been negated by the down angle of the lower unit? :-?


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## goon squad (Jun 5, 2013)

> Is that an optical illusion, or is that outboard tucked so far in, that the lift provided
> by the jackplate has been negated by the down angle of the lower unit?  :-?


I figured Brett would pick up on that, Yes it was tucked way in at the time of pic. after adding batt and cooler up front I was able to trim it correctly.  If I still had the boat I would take some better pics. Now I have to start over with another one. btw that Noe would run 23 mph with 8hp Suzuki.


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## Jeremy_James (Feb 27, 2013)

Basically I am more confused after making this thread due to all of the completely opposite and different answers. 


I don't mind investing the $300 in a Jackplate and trim tabs for my Classic if it makes a significant difference. There has to be someone that has tested a manual JP and stationary tabs with PURE results. Anyone anyone? lol


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## JRP (Sep 24, 2012)

Just go with the Bobs manual jack plate ,forget tabs and put more weight forward thats all you need.I love this set up on my LT.It makes it so much easier to prop the boat out properly,also to change engines.When I know ill be running in thick floating weeds I mark on the jack plate where the engine was and move it down some and do to the bottom configuration dont pick up the amount of weeds around my lower unit which makes these smaller engines go into the default overheating mode as much which is a real PIA.


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## Brett (Jul 16, 2008)

my motor without a Jackplate takes a significant amount of water to run/hole shot @ approx 12" +/-.

Even with a jackplate it'll need about 12 inches to get on plane, even spinning her up on top.


I am afraid that if I put a Jackplate in the back and setback my motor 4-5" further back that my Gheenoe will be too ass-end heavy a

Adding a jackplate will be like adding  about 15 lbs to the transom.
Lose some of the uneccessary crud you carry and shift some load forward
to eliminate and balance the weight.

Your real worry will be replacing the prop with one capable of biting in aerated water
and making sure the water pump maintains pressure when lifting the engine up..
The location of the water intake determines how high you can lift the engine.

Another thread: http://www.microskiff.com/cgi-bin/yabb2/YaBB.pl?num=1235777190


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## goon squad (Jun 5, 2013)

Vertigo, From my experience with a 15'4"highsider is that I wouldn't have one with out a jack plate, If you only gain 3" that is 3" more than you had before. if you ever run in oysters it could save your skeg and or prop,or save some sea grass in the flats, and you will have less drag meaning more speed. My suggestion is to buy or make one with the least amount of set back and as light as possible. The one I had was around 6-8 lbs. 

Install your plate.

Load your boat as normal

Trim motor to correct angle  (Brett has links for how to do this)

Raise motor a little at a time test drive as you would normally drive, as in, hole shots, cornering ect. after each adjustment. Take it as high as you can while maintaining good water pressure and with out the prop blowing out.

If you are happy with the results stop there. If you want to go higher you will need to invest in a prop with more bite, if you already have a ss prop you should be able to have some cup put into it and re-pitched (if needed) depending on your rpm's at wot. (If you can, borrow a prop to try, you don't want to rework a good prop and find out you can't go any higher because of a water pressure issue.)

That is my suggestion, it worked for me.

There's not much more embarrassing than bumping bottom in a Gheenoe!      Good luck.


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## goon squad (Jun 5, 2013)

Sorry I meant, Viper, my bad.


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## backwaterbandits (Dec 15, 2006)

I ordered a Bob's manual plate on my LT 25 when 
  new. I had a brand new 25 2stk Yamaha with a 
  stock alum prop and I could not get any bite at all
  with the JP all the way down. I installed a Bob's Tru
  Tracker and a Power Tech 4 blade prop w/ heavy 
  cupping and raised the JP all the way up...Runs
  great and has been that way ever since...


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## anytide (Jul 30, 2009)

just go fishn and leave it be.........


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## Dan8383 (Nov 22, 2018)

Marshfly said:


> You guys are way over thinking this. In my eyes, a jackplate isn't used to "setback" the motor. It's used to raise the motor to take advantage of the enhanced grip characteristics of a heavy cup prop. With my prop/jackplate combo, I can't get max rpm without having the JP almost all of the way up. The prop simply has too much grip to allow it with the horsepower that I have. That increased grip combined with the props ability to not blow out while having the upper surface of the blades above the surface of the water is what allows me to raise the motor giving me less draft. The jackplate allows me to raise the motor substantially higher than I would if it were simply bolted to the transom.
> 
> Setback doesn't even come into play.
> 
> And that's the facts, Jack.


What is your average inch draft on plane?


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## Smackdaddy53 (Dec 31, 2012)

Dan8383 said:


> What is your average inch draft on plane?


A lot can change in 5 years


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## Dan8383 (Nov 22, 2018)

Smackdaddy53 said:


> A lot can change in 5 years


Lol true but I just had to ask and hoping you would remember since I might get one


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## permitchaser (Aug 26, 2013)

I love my JP and think they should be on every skiff but not on a Classic G


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## No Bait / Lures Only (Apr 10, 2011)

Jeremy_James said:


> Basically I am more confused after making this thread due to all of the completely opposite and different answers.
> I have fixed trim tabs n manual jack plate
> 
> I don't mind investing the $300 in a Jackplate and trim tabs for my Classic if it makes a significant difference. There has to be someone that has tested a manual JP and stationary tabs with PURE results. Anyone anyone? lol


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## No Bait / Lures Only (Apr 10, 2011)

Jeremy_James said:


> I have never broke out a ruler and measured my exact running depth. I am estimating the depth. The measurement from my cavitation plate to the bottom of my skeg is dead on 11".
> 
> Even with that being said, if the motor is set back 5" can't the motor come up at least 2"?


Each boat is different, like r n d, adjust n run, over again. Etc. Until motor ventilated n lower till it stops.
All my boats have jack plates n it helped.


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