Questions for those of you who have rebuilt your transoms...

[jbrinch88]

I'm getting to the end of the structural part of my transom rebuild on my 24 offshore ( open transom ). Original transom core was 2 pieces of 3/4" ply and an additional 1/2" piece of ply and about 1/4" glass inside and out.

I rebuilt the transom using 3 pieces of 3/4" merante marine ply, west systems epoxy, and 3 layers both inside and out of 1708. Is this enough layers of glass? Using a straight edge it appears I'm close to the original outside skin. I'm told the overall amount of glass isn't as important as most of the strength comes from how it's tied back into the floors, stringers, and hull sides.

I removed both rear stringers and replaced with doubled up 3/4 merante with 2 layers of 1708 and also tabbed them into the floor, forward bulkhead, and transom using 2 layers of 0/90* biaxial cloth ( heavier than 1708 but I forget what it's called). Also tabbed the transom into the hull sides, floor, and stringers using the same fabric. All structural parts are tied into one another at multiple points with my tabbing and transom skin.

I'm thinking I'm finished structurally overall and ready for fairing however this is my first transom I've done and planning on mounting a new 250 or 300 Yamaha onto it in the spring. Rather be safe than sorry.

Thanks

Jason

 

[jbrinch88]

Here are some pictures ( 2nd pic is before i laid the last few layers down wrapping the outside/inside)

 

[jbrinch88]

Some additional pictures :

 

[Jonah]

Nice work. I might need something like this soon, but what you've done is way above my skill level. I'm replying mainly so that I can 'watch' the thread and see what others say in reply.

 

[DennisG01]

I'd say you have plenty of glass! Looking good, there. I like that you drilled holes in the ply before glassing the transom skin - as you know, you would ended up with major air pockets without doing that.

Have you though about tieing the transom into the stringers in a more structural way? If you have the room, it's cheap and easy to do it now and it certainly can't hurt. Click the images to make them bigger.

 

[jbrinch88]

Dennis, the holes in the outer skin were screw holes I drilled to fasten the first layer of plywood to the outer skin. I wanted to use clamps but since I raised the height and closed in the sides, I had no clamps large enough to hold the core to the skin. I removed the screws once the thickened epoxy cured.

I fastened the additional layers of plywood the same way but from the inside. I chose to leave the screws in since they were countersunk and just filled them. I also staggered the joints of each layer of core. Wasn't able to fit the whole core in one piece under the gunnel.

The new stringers are pretty stout. Won't let me post certain pics they're too large. They're double the thickness of the original ones and also amount higher up on the transom. They're also completely covered in glass unlike the original ones ...

I'm pretty confident in the overall structural I just won't know until I know...you know?

Compared to what was originally there which was a joke. I was able to knock out the old stringers with just a few hard hits with a hammer.

 

[SkunkBoat]

1708 is good for tabbing because it tucks and stays and its good for finish because it is smooth. It doesn't have a lot of "beef" and doesn't hold a lot of resin.
I'd go with some 24 oz woven roving across the whole inside and connecting the stringers. fyi, It soaks up a lot of resin
If you use it on the outside you'll never hide the bumps.

Job looks good.
Will there be a motor well added back? That connection back to the cap(deck) will add strength holding the top of the transom forward.


I'm happy to see you didn't just cut off the outside skin and try to paste a piece of plywood to it and cover it.

 

[jbrinch88]

1708 is good for tabbing because it tucks and stays and its good for finish because it is smooth. It doesn't have a lot of "beef" and doesn't hold a lot of resin.
I'd go with some 24 oz woven roving across the whole inside and connecting the stringers. fyi, It soaks up a lot of resin
If you use it on the outside you'll never hide the bumps.

Job looks good.
Will there be a motor well added back? That connection back to the cap(deck) will add strength holding the top of the transom forward.


I'm happy to see you didn't just cut off the outside skin and try to paste a piece of plywood to it and cover it.

I used the heavier fabric to tab the stringers and transom in. I forget what it's called but its 0/90 stitched with CSM stitched to the back of it. I used the 1708 mostly just to encapsulate and layer all the new wood.

I'm planning on piecing the old floor/well back in.

 

[suzukidave]

it looks good. the only question i have is are you going to glass the side walls of the splashwell back in?

 

[UCPA111]

I used 1708 on my transom rebuild. I think you're in great shape with what you've done. I put a bracket on mine (got rid of cut through transom and made it full height) and mounted a 300 Verado. No flex or bounce or cracks. You should be good to go. I used 2 pieces of coosa board epoxied together. Tabbed it all in. Added some connections to the main deck and structure of the inside of the boat. I've observed a number of videos with 1708 being used. It's strong. I fish Lake Erie and it is rough and snotty at times...so I know I've tested the strength.

Here is one of my videos (you can find them all on my Youtube page).

 

[jbrinch88]

it looks good. the only question i have is are you going to glass the side walls of the splashwell back in?

I'm planning on glassing everything back in the way it was.

 

[jbrinch88]

I used 1708 on my transom rebuild. I think you're in great shape with what you've done. I put a bracket on mine (got rid of cut through transom and made it full height) and mounted a 300 Verado. No flex or bounce or cracks. You should be good to go. I used 2 pieces of coosa board epoxied together. Tabbed it all in. Added some connections to the main deck and structure of the inside of the boat. I've observed a number of videos with 1708 being used. It's strong. I fish Lake Erie and it is rough and snotty at times...so I know I've tested the strength.

Here is one of my videos (you can find them all on my Youtube page).

I've watched your videos many times and its giving me more confidence seeing how you have added a bracket and a heavier outboard than what I'm planning and you had no problems.