Raising transom to 25"

[awthacker]

I made the decision this week to repower instead of screwing around with the 1984 Evinrude. After it was gone, my plan was rebuild the transom and raise it to 25" before the repower. Problem is that the transom is in great shape. How can I raise the height of the transom without unneccessarily destroying what is there? Or should I use some kind of bracket to elevate the engine?

[Bruce]

Jack plate would work wonders in this situation.

[Blu_Lunch]

Jack plate would work wonders in this situation.

That is exactly what we did.

[awthacker]

I was also considering the benefit of keeping more water out. My boat will almost exclusively be an offshore fish/dive boat, and I like the idea of raising it.

Trying to determine if there is a way to fill the notch without cutting out the existing wood. I was kinda thinking if I take a chainsaw and cut a three-quarter inch wide groove two or three inches deep accross and up both sides of the notch; then I could resin in a piece of 5/8 ply cut to the final shape. Then add 1/2 inch ply on the front and back. Then glass over it all.

Maybe this picture I edited will help explain. Does this sound like it would have the structural integrity I need?

[tsubaki]

Even doing that I'd have a plate on both sides of the transom just to be sure.
Fixed jack plate or any other jack plate would be a lot easier. You could dam off the remaining 5" with a number of things just using the existing top bolt holes.
Not necessarily this manufacturer but you get the idea.
http://www.marineengine.com/products/accessory.php?in=3428884
I'm not sure if a simple setback bracket will have the range of lift needed.
http://www.bobsmachine.com/Products/setback_brackets.cfm

[tsubaki]

When I thought I had burned up the first motor I had on the boat (which was a 20"), I found a much newer 25" for a reasonable price. Raised the transom I had poured and packed with fiberglass earlier. Did the same for the added 5".
Come to find out the old motor had only minor detonation on one cylinder.
While making a plate for the pour, I just did a little more work and made it permanent.
http://i175.photobucket.com/albums/w159/tsubaki3/johnson008.jpg
http://i175.photobucket.com/albums/w159/tsubaki3/johnson009.jpg
http://i175.photobucket.com/albums/w159/tsubaki3/johnson.jpg

[awthacker]

I like that bracket. But, I think I'm gonna leave it at 20" for now. I have a shop building a carburated 2 stroke for me and they can build it at 20", so I'm just gonna glass this over and paint it with Perfection.

[parishht]

Just my own personal situation and wondering what to do.
I already know that I have to re-build my transom and I did burn up my 20" shaft motor.
I need to replace both and I am seeing more 25's than 20's (motors) so my transom looks a lot like awthacker's.
I was wondering if I would be better off just rebuilding the transom to accept a 25" shaft?

[tsubaki]

Reason for me doing what I did.
At least for around here, usable 20" motors in the 150hp class are a real booger to find.

[Blu_Lunch]

I used a jack plate and dammed it off with 1/4 starboard and sealed with 5100, it is not structural but it keeps the water out.