# Transom rebuild or jack plate??



## Bass n flats (Nov 4, 2012)

I have acquired a new 25hp tiller steer and took it out yesterday for a test run. The motor runs great but the cavatation plate sits about 2 inches higher then the bottom of the transom. My question is should I cut down the transom in the middle or should I build a jack plate type bracket to drop the cavitation plate down to the correct level? I am unsure if cutting down the middle will lessen the strength of the transom, but will a jack plate offer too much set back and lower to the point where the tiller handle will not reach over the transom?


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## Bugpac (Nov 4, 2012)

Is it caveating when you turn, and are you maintaining water pressure from the pee hole? I would buy the th marine mini jacker if i needed it moved, cant hardly build one for a 100 bux.


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## Bass n flats (Nov 4, 2012)

Yes and yes as I give it more throttle it starts to sputter on the tell tail and then a huge rooster tail. My wife was watching it and it would do that every time. I just don't know how a low set jack plate will affect the steering with the tiller arm it seems like it would rub on the top of the transom


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## Bugpac (Nov 5, 2012)

I cant imagine it needs to go down much, and the further the setback the higher you can be, cutting the transom kills the boat imo, unless its a pos i wouldn't do it.


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## lckstckn2smknbrls (Nov 5, 2012)

The rise to setback formula I know of is .25" rise for every inch of setback. So if your 2" too high you will need around 8"of setback. If you can lower the motor .5" all you should need is 6" of setback.


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## Bass n flats (Nov 5, 2012)

I'm leaning away from cutting the transom down the 2+inches I need and just going with a jack plate type set up. I know its a lot of trial and error. If i'm reading lckstck's post right the 1/2" of drop and 6" of setback should place it in enough "clean" water to prevent the problem?


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## Bugpac (Nov 5, 2012)

I don't think you need to go down 2" myself. I would get the th marine jp and mount it .5" lower, i think its a 3" set back. Use lower holes when you mount so you can drop another .5 . Th marine mini jacker.


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## Bass n flats (Nov 5, 2012)

I've looked at those and i'm kinda leaning towards them but I'm also thinking about going the more adjustable route with making one out of aluminum angle, just for the fact of a couple times a year I run shallow on the flats/around oyster bars and would like to be able to raise it while putting through these areas, just a thought though. That would give me 3-5" of set back and I should get up to 2" of drop if needed.


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## lckstckn2smknbrls (Nov 6, 2012)

I have the mini-jacker. There is not enough setback to allow the motor clamps to fit in between the outside of the transom and the mini-jacker if your trying to use it to lower the motor.


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## Bass n flats (Nov 6, 2012)

Good tip something I wouldn't have looked at before I purchased.


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## nick4203 (Nov 7, 2012)

just fab up a jack plate looks like you could easily go down at least a inch with out rubbing that would bring the setback to 4 inches right? thats not out of the question seems like it would be fine 

mabe get rid of the tiller and get a steering wheel set up but i think the jack plate is a better option


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## Bass n flats (Nov 7, 2012)

I'm gonna keep it a tiller because I do fish a lot of electric only and its nice just to take it off. I'm working now on getting the materials together to make the jack plate. 3-4" of set back with up to 2"+ inches of drop


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## Bass n flats (Nov 9, 2012)

While digging through my scrap aluminum pile I found some 3x3 1/8" thick angle. Do you think the 1/8th inch will be thick enough or should I go with the 1/4"???


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## lckstckn2smknbrls (Nov 9, 2012)

I'd go 1/4" min.


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## Bugpac (Nov 9, 2012)

3/16 is common and would be ideal if built right.


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## richg99 (Nov 9, 2012)

My mechanic here in TX, who I've used and trusted for 15 + years, says every two inches of setback will yield one inch of rise. He is a certified Evinrude tech and the smartest engine guy I ever met.

So, using his methodology, you only need four inches setback to gain the two inches. Rich


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## Bass n flats (Nov 22, 2012)

In preparation for the jack plate I reinforced the transom just a little bit and also cleaned it up. I'll be ordering the 4x4x1/4 tomorrow and should be able to start next week.

Before 






After





I removed the old cap and replaced with thicker angle as well as some new corner bracing on the splash well. This should stop the little bit of wobble on the top of the transom? I thought I had enough hardware to complete today but I will have to venture out tomorrow to get 4 more SS bolts to complete.


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## Bass n flats (Nov 29, 2012)

in doing my research on jack plate construction I see that everyone is laminating 2 pieces of plywood for the motor board on the jackplates. What problems may I run into with using a 2x8 or 2x10 in its place?


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## lckstckn2smknbrls (Nov 29, 2012)

Bass n flats said:


> in doing my research on jack plate construction I see that everyone is laminating 2 pieces of plywood for the motor board on the jackplates. What problems may I run into with using a 2x8 or 2x10 in its place?


Dimensional lumber cracks easier then plywood.


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## Scout27 (Dec 1, 2012)

I agree witht the 1/8" not being heavy enough. I think 1/4" would be a minimum, especially if you're going to make it adjustable.

I had a CMC trim/tilt jackplate on my last 1648 and I believe it was 3/8". Their webiste would verify that if you want to check. I had a 25 Yamaha on it.


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## jigngrub (Dec 1, 2012)

Tiller motors never really work right on console boats, and will be uncomfortable to operate for an extended period.


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## Bass n flats (Dec 1, 2012)

I was able to work on the jack plate today. I get about 1" of drop and 2"+ of rise. Once I get the motor board finished tomorrow and get the whole thing mounted I will be able to water test next weekend.


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## Bass n flats (Dec 2, 2012)

I got the JP mounted today and gained just over 6" of setback. Waiting on the motor board to dry and then heading to the lake Saturday to test.


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## kfa4303 (Dec 2, 2012)

Looks great! I made a similar fixed transom riser for my old '66 20 hp Johnson and it's helped quite a bit. I can run shallower, get on plane more quickly and it puts the motor at a more comfortable operating height too. Good luck on the sea trial!


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## Bass n flats (Dec 9, 2012)

I got to run the boat with the jack plate adjustments yesterday. With just me and regular gear I peaked out at 24.8 but could cruise at WOT at 24. With 2 people it ran very smoothly at 21 and with 3 18 mph. 

I have the JP level with the transom and the tilt is on the first hole down. During a turn I am still getting a little bit of cavitation I'm not loosing near as much power as before. 

I am also getting a v shaped rooster tail that is being caused by water hitting the front of the exhaust housing just above the lower unit. Any recommendations on how to correct this? 

We ran out of gas yesterday so I had to stop trying combinations to find the best one. If anyone has any thoughts let me know.


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