Should I fabricate a jack plate for my boat?

[Casey Lynn]

Since you seem to be good at fabricating……
Four pieces of aluminum angle.
Vertical slots cut in two of them, bolts, washers and locnuts for the others. Use this to adjust the engine height of whatever engine you choose.
On the outside you will want to do plate aluminum to be used as a stiffener for the angle pieces then wood on the outside and whatever you like to seat the transom clamp cups against on the inside.

This one is made a little different. With the one described above the height adjustment will be on the sides.
Notice the difference between two different short shaft engines. The Speeditwin required the jack plate be all the way up.
The 3-cylinder 25 only likes to be about 1.5" above even with a modified prop.
NO two engines will be the same and every prop you change should require small changes as well.
Yes I know there is cutting board on the outside of this one and that is slippery. There is a bolt and nut between the transom clamps on the square tanker and I through bolt the 25hp.

[vintin]

The Hi Jacker on my 1958 Feather Craft Vagabond w/ 1957 35hp Johnson. That’s a one inch thick piece of mahogany that spans the gap in the aluminum angle and that the motor mounts to.

[Casey Lynn]

Yep, that is the easiest one to make. The height adjusters are gravy. Not needed but very nice to have.

[vintin]

Nice Jack Plates you’ve got there Pappy.

I’ve got about $170 plus wood in my Jack Plate set up. I’m sure you only got a fraction of that.

[Casey Lynn]

Not really. $165 already built.

http://www.bobsmachine.com/Mini-Manual- … 200500.htm

[vintin]

I though you’d fabbed them yourself.

Not that they look homemade………they look pro all of the way!

[dan-in-tn]

Gee, you guys amaze me. I am from bass boat country. I know all about professional jack plates. I thought Mr. Asa just wanted something temporary to try to see if it would make a difference before he drilled holes in his transom and all of that. My way was a VERY down dirty and CHEAP way to do what he wanted to see if it would make a big change on his old 15hp motor. Those old bull nose gearcases won’t take much raising without a lot of prop work. I was just using a couple of c-clamps and pads to clamp to the transom and raise the motor for a quick run. Am I talking to the same people who won’t pay for carburetor packing? !!!

Dan in TN

[vintin]

Hey Dan,

I’ve got my 57 35hp up almost 4 inches. The anti ventilation plate is almost exactly even with the bottom of the hull. I had it jacked up a bit of wood and one day after boating I lifted the motor to put the transom saver in place and the motor rotated on the transom! I was going to lose that motor and it was only up 1.5 inches. My hijacker is on a 1958 Feather Craft and it’s spaced such that a 1973 50hp short shaft Johnson, should I get it running, would be a easy swap.

Got a cheap source for those packing washers? I’m all ears. 😀

[mr-asa]

Fabricating something out of aluminum is a little more than I was thinking of, honestly.

I was just thinking of taking the rear wooden plate on my transom, transferring that pattern to another piece of wood with an added 2-3 inches, then adding a support immediately above the transom. Basically adding a new rear plate that could be bolted and unbolted fairly easily.

For reference here’s a picture of the back of my boat, along with my older sister and I on the Wakulla River

[Casey Lynn]

Asa – Anything you try will work, there’s no question about that.
The idea behind a jack plate is to optimize the performance of a particular boat/engine combination.
In our hobby we use the same boat for several different engines. Therein lies the problem. No one height will work for all engines.
OMC made all kinds of changes to mid-sections throughout their history. Almost none of their "15 inch" engines ever measured at 15". Anytime there was a mid-section change the overall transom to cavitation plate length probably changed as well.
Some gearcase designs are capable of running higher than others. See how high I had to run the square tanker?
Now…..add all of the other manufactures, past and present, into the mix and the differences in measurements on each "15 inch" engine will boggle your mind. No two are the same.
Back to my first comment. "Anything you try will work, there’s no question about that"
A true adjustable jack plate just makes it easier to optimize all of the different engines you are likely to run in your future engine projects.

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