Jack Plates

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Joseph Elliott
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Jack Plates

#1 Post by Joseph Elliott » Sun Jul 19, 2015 10:26 am

I am having a hard time finding a used motor that will work for the pontoon I am building and thought that if I can't find a motor with a long enough leg perhaps I can lower a smaller motor. 26" toons and height from the top of the transom to the bottom of the toons is approx 27". Would a jack plate work to lower a motor with a 21" shaft low enough? I really don't want to spend $15,000 on a new 90hp ......
Alberta, Canada
Home made 16' pontoon, 1980 60HP Johnson- work in progress

Seon
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Re: Jack Plates

#2 Post by Seon » Sun Jul 19, 2015 11:38 am

Joseph Elliott wrote:... Would a jack plate work to lower a motor with a 21" shaft low enough?
Problem will be that your power head will be awfully close to the water line. Best to search for a "salvage" motor with a 25" lower unit, swap it then use a jack plate because you're still two inches shy.
1989 28' Tracker Party Hut
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Bamaman
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Re: Jack Plates

#3 Post by Bamaman » Sun Jul 19, 2015 11:53 am

Just because your toons are 27" doesn't mean that the manufacturer didn't allow adjustment in the engine pod height so it'd be correct to use a 25" motor.

We seldom see jack plates on pontoon boats because hanging engines back also places pressure on the transoms. Pontoon transoms are relatively weak anyway. For example, Bennington doesn't want jack plates on their boats--structural reasons.

Go for the 25" motor found on must pontoons. Chances are it'll be just fine. If not, cut down the transom slightly.
'12 Bennington 24' SSLX Yamaha 150

Joseph Elliott
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Re: Jack Plates

#4 Post by Joseph Elliott » Sun Jul 19, 2015 12:03 pm

It's finding a 25" motor that is the problem :) They are very scarce up here, I have been searching for almost a year now and not a single used one has come up.
Alberta, Canada
Home made 16' pontoon, 1980 60HP Johnson- work in progress

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lakerunner
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Re: Jack Plates

#5 Post by lakerunner » Sun Jul 19, 2015 4:44 pm

If we only knew where up here is.

This is why you need your location and boat/motor brand and hp. in signature line
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Joseph Elliott
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Re: Jack Plates

#6 Post by Joseph Elliott » Sun Jul 19, 2015 6:41 pm

Signature fixed :)

The boat is one I am building myself from the ground up. 26" toons, 16 feet long. I was unable to find a floor plan that I liked when I was shopping for a boat so I decided I would build my own.
Alberta, Canada
Home made 16' pontoon, 1980 60HP Johnson- work in progress

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lakerunner
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Re: Jack Plates

#7 Post by lakerunner » Sun Jul 19, 2015 8:44 pm

My tracker has 26" tubes and standard long shaft works. You might have to buy new if used is unaviable
Loyd & Betty Meeks
Livin the lake life
2004 Tracker 22 Regency/2010 90 E-Tec. Pulled by 2017 F 250,
McAlester, Oklahoma
Moving toon back to Tenkiller


Looking forward to the day BLM no longer exist in this world because they don't

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ToonGuy
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Re: Jack Plates

#8 Post by ToonGuy » Mon Jul 20, 2015 10:06 am

Could you post a picture of the rear of your set up?
Just one boat...after another, after another :-)

Joseph Elliott
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Re: Jack Plates

#9 Post by Joseph Elliott » Wed Jul 22, 2015 3:52 pm

As requested here is a pic of the back :)
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Alberta, Canada
Home made 16' pontoon, 1980 60HP Johnson- work in progress

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ToonGuy
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Re: Jack Plates

#10 Post by ToonGuy » Thu Jul 23, 2015 5:15 am

I'm guessing you'll be fine with a 20" shaft. Most newer 2-log toon run a 25" tube, and while they do have some drop to the back of the transom they also have more riser on the tube then you do. Given the information in this post, I'm betting a 20" shaft 90HP on your boat will work fine (assuming your layout doesn't bias the weight to front too bad).

Check out the picture below. This toon has 25" tubes, a slight drop in the transom, but taller risers then your boat does. I had to drill another set of holes so we could get the motor UP HIGH ENOUGH to get the prop running clean.

Worst case if you get it in the water and it cavitates too much, you could always cut 2" or so out of the top of the transom and weld a cap on the top. That should give you plenty of adjustment, but I would try it as it first.
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Just one boat...after another, after another :-)

Joseph Elliott
Posts: 37
Joined: Fri Aug 29, 2014 5:47 pm
Location: Alberta, Canada

Re: Jack Plates

#11 Post by Joseph Elliott » Thu Jul 23, 2015 9:15 am

Thanks ToonGuy, I was under the impression that I had to measure the leg length like a mono hull - top of the transom to the bottom of the toons - to get the correct leg length. I will definitely try it with a smaller leg and see if it works.
Alberta, Canada
Home made 16' pontoon, 1980 60HP Johnson- work in progress

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ToonGuy
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Re: Jack Plates

#12 Post by ToonGuy » Thu Jul 23, 2015 10:24 am

Definitely not...this issue comes up often and it can be quite confusing. Let me explain:

First, let's use the term "Cavitation Plate". This is really the important factor. In a perfect world we want our cavitation plate to be at the top surface of the water or slightly under while under full throttle.

On a full center tube tri-toon, you can set up just like a mono hull, because the cavitation plate will always ride in generally the same flow of water while under full throttle. There are very little variables, just like a mono hull.

On a 2-log pontoon, there are just too many variables. In this instance the motor transom should never actually be in the water, so the height of the cavitation plate in relation to the flow of water is always variable. Example: look at a 2-log boat and a full tri-toon moored in a wet slip. If 2 adults walk from the bow to the stern of both toons, the cavitation plate on the 2-log boat will drop in the water substantially, but the water itself does not change. On the tri-toon, although the cavitation plate will also drop deeper in the water, it's relation to the bottom of the transom can never change. Because the flow of water has to go under or around said transom, this is the reason we set up tri-toons similar to mono hulls.

So to summarize...the cavitation plate on a tri-toon will always ride in generally the same conditions just as a mono hull. But on a 2-log toon it's infinitely changing. Simply moving 1 adult from the front to the back will change where the cavitation plate rides in relation to the waters surface and can completely alter the way the boat rides and handles.
Just one boat...after another, after another :-)

Joseph Elliott
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Location: Alberta, Canada

Re: Jack Plates

#13 Post by Joseph Elliott » Thu Jul 23, 2015 11:34 am

Ok, so a 25" shaft would be probably be too long then?
Alberta, Canada
Home made 16' pontoon, 1980 60HP Johnson- work in progress

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ToonGuy
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Re: Jack Plates

#14 Post by ToonGuy » Thu Jul 23, 2015 1:26 pm

Most likely. Like I said...your toon is unique so there is nothing set in stone. But as long as you are not light in the stern I'm betting you will be fine with a 20". Even if it would need tweaking it wouldn't be over the expense of locating a 25" shaft motor.

I once had a 24' toon with 25" tubes and a 40HP Johnson with a 20" shaft. With that light motor and my lay out the boat was somewhat light in the stern.Everyone always wanted to sit up front, and on a rough day it would cavitate sometimes. Usually moving one person to the back would completely eliminate the issue. When I swapped a 90HP on it never happened again.
Just one boat...after another, after another :-)

Joseph Elliott
Posts: 37
Joined: Fri Aug 29, 2014 5:47 pm
Location: Alberta, Canada

Re: Jack Plates

#15 Post by Joseph Elliott » Tue Jul 28, 2015 2:42 pm

Thanks again ToonGuy, I have another question for you. Where does a person find parts for older consoles? I purchased the console in the attached picture from Great Lakes Skipper knowing that it would come as is. I didn't think it would be difficult to find the correct panels if I contacted Harris Kayot; I was wrong, Harris was unable to help me lol. Is there a company out there that sells replacement panels for boat consoles? The piece I have no idea what goes there is the large odd shaped hole to the left of the steering column. I am also trying to figure out what went on top in front of the cup holders (beside the sink in picture 2).
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Alberta, Canada
Home made 16' pontoon, 1980 60HP Johnson- work in progress

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