Mini-jacker ???

I am looking at getting a mini-jacker from BPS and was wondering if anyone has one of these ?
I have a long shaft motor on a short shaft boat and seen these for a quick/easy fix.

If you do , what is the height of the mounting flange(where the bolts go through) that mounts to the transom ?

Also , did it NOTICEABLY help with the perfomance of planing out etc. ?

Thanks ahead for any replies

I have one on a long short shaft motor on a 15" transom. The river I'm on can get very shallow.
There are series of dimples on each side it that you drill out to get the proper fit.

In your case, with the mismatch of shaft length vs transom height the performance difference should be very noticeable. Try and mount it to where the cavitation plate is about even with the bottom of the boat measured when the plate is parallel to the bottom not trimmed in or out. That would put the jack plate higher than the transom as a starting point am guessing. I have one on a 13' Gheenoe and just installed a Bob's Machine Mini Adjustable plate on another Gheenoe.

I've made several jack plates using 3x3 aluminum angle, spaced wide enough for the engine, and high enough, so that the anti-cavitation plate above the prop is lined up with the bottom of the hull.

Mount the angle to the hull and put in the transom boards you need. I used 3 pieces of 3/4 plywood to get the 2 1/4 inch thickness of a transom. Not all transoms are that thick, but 2 1/4 is about all the thickness you'll need. I glued them together over night, and mounted the transom board the next day.

Mount the motor and measure up from the motor plate to the bottom of the hull and that will tell you how high to mount the angle sticking up above the transom.

The last one I did was for a 25 Merc because they measure 18", not the 15" or 20" that most other motors measure. The mini jack plate shown above is only a 3" rise I believe. If you need 5" it's cheaper and you get what you need if you can make your own.

Thanks for the replies , I ordered it already and it should be here this week sometime. when i bought the boat , they used a 2" x 2" piece of wood to raise it up. was thinking about mounting top of jacker mount flange even with top of transom and re-using 2 by 2 again in case i might want to move it up or down in the future. but i could just move jacker too i guess.

I just bought the boat from a friend and took it out for about 5 mins to make sure everything worked. He told me everything worked fine but the motor needed to be raised up. i probably wont notice a difference.

this is my first boat ever and i think i got a good deal SO FAR.

Instead of thinking why not measure? You have two replies that indicate you will probably be above the transom to start with. Of course theres that old saying about never having time to do it right but always have time to do it twice! Without me measuring, am betting once again that your top of the mount flange will need to be (a minimum of 2-3") above the transom. There are dimples in the plate that can be used as drill guides for raising the plate. Use them! Your thinking would be closer if you had a 15" engine to start with, you don't. Most cavitation plates are at least an inch below the bottom of the boat plus your engine is 5" too long to start with so there's a minimum of 6" just to start with to bring your engine close to where it needs to run.

I put the motor back on , put a level on bottom of boat (for a straight edge) and measured the difference. cavitation plate is 5 inches from bottom of boat.

I probably will still want to put a piece of wood ( 2 x 2 ) on top of plate right ? to keep motor and plate from rubbing together ?

3 inch rise from mini jacker + 2 inch rise from 2 x 2 = 5 inches

should do it. right ?

BOLT that engine to that jack plate when you get it mounted.

Mount that jack plate as high as you can to get as close to the 5" that you need for the best performance. It looks like your jack plate will set the engine back about 3", meaning you could go another 1/2" higher.

Looking at that jack plate, I can see mounting a transom board to it to get the height you need. Anchoring the top of the board to the jack plate, with two bolts wider than the engine mount, and using the lower holes in the engine mount to anchor the bottom portion of the board, using two more bolts through the engine mounts, jack plate and board. This would eliminate your need to shim it 2" higher, and give you a more stable surface for your engine.

Thumb screws would be biting into wood, and bolted at the bottom.

Watcha think, Pappy?

There is nothing wrong with mounting the flange of the plate higher than the transom to start with. It is made to do that. That plate comes with wood on the inside of the plate to mount the engine with. I say mount the plate at the right height to begin with. There is plenty of support for the plate and engine if he has the wood on the inside of the transom for (4) plate holes through the transom. Would like to see the cavitation plate around 1" above the bottom if possible. Again that measurement is made with the plate parallel to the bottom and not angled down or up. Engine will only need its clamp screws and the two optional mount screws to be secure. You do not want to place a 2 x 2 above the plate to keep the engine from rubbing. That is a non issue and will place additional stress on the clamp screw geometry of the engine brackets. Small engines have been mounted right on the tops of transoms for the last 102 production years with no issues.

Can you use this plate for the reverse situation? I have a 17" shaft on a 20" transom. I need to lower my motor.

Howard said:

Can you use this plate for the reverse situation? I have a 17" shaft on a 20" transom. I need to lower my motor.

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I dont advise it. Itll work, but its aggravating. you cant tilt your motor up all the way

Perhaps you two guys (Howard from GA and the OP from WI) could swap your motors..... Rich

The reason you see a 1" wood shim in my pictures is that I was experimenting with different motor heights. I have remounted the mini jack plate higher.

OK , Thanks for the replies , I was probably making more out of it than i needed to but just wanted input from people with more experiance than i have.

Thanks again

Here's my two cents:

I had the same issue of a longshaft motor on a 15" transom boat. I looked into the jackplates but none of them looked that great. So, i decided to design one specific for my application. Here are the results:

The riser is 6" taller than the transom and sandwiches the transom both inside and outside of the boat. I used (4) 3/8" bolts to mount it to the boat and the motor clamps to the riser.

I dont advise it. Itll work, but its aggravating. you cant tilt your motor up all the way

Click to expand...

Ah, didn't of that. Im down to that or cutting the transom. Maybe tradeing.....

looks nice clark , would you trust a 30 hp motor on that ?

Howard said:

I dont advise it. Itll work, but its aggravating. you cant tilt your motor up all the way

Click to expand...

Ah, didn't of that. Im down to that or cutting the transom. Maybe tradeing.....

Click to expand...

I cut mine down, and it worked out great. Here is the link:

https://www.tinboats.net/forum/viewtopic.php?f=21&t=12719

I cut mine down, and it worked out great. Here is the link:

Click to expand...

Thanks, I can not use the mini jacker. It does not allow enough room for the turn handles unless I want to I fur it out myself. My only concern with cutting the transom is weakening it. Yours looks great btw. Looks professional.

With regard to cutting down the transom...many of the Carolina Skiffs wind up with their transoms cut out to accommodate a shorter shaft motor. Of course, that is pretty thick fiberglass. I don't doubt that it can be done on any sturdy boat, though.

However, it might be a lot easier to just sell the short shaft motor (especially since it runs so well) and then just buy the right length motor to fit your boat. Rich