Radon Transom Replacement

Questions about boat repairs with our resins and fiberglass: hull patches, transoms and stringers, foam, rot etc.
bigtalljv
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Radon Transom Replacement

Post by bigtalljv »

Well it's not a huge surprise after I started to dig into this that it needs a new transom. The work done on this boat has been really shoddy. I pulled the outdrive transom unit and there was a puddle of standing water down there where they left a lip. The wood was all swollen and it didn't take much to do this. Pulled the big chunks off with my hands. Not the end of the world, I've never replaced a transom, guess I'll be able to cross that off the bucket list.

Transom replacement shouldn't be the end of the world. I'll have to review the tutorial, I've read plenty of threads, just never paid that much attention because it was relevant (then).

One concern is I'm not sure how thick the exterior skin is. Seems a little thin. Hopefully not an issue.

I'm not sure about the stringers. There might have been some exposure but they also look to be wood and not plywood. If they are original from the 70's I would guess that is probably a fact. They notched the stringers to get the new bravo exhaust Y-pipe in there. Can I trim the stringers a little lower in that area? Unfortunately it's the 8" right at the junction to the transom. Can I supplement with width? Double up or something? it's only a little bit the need to be trimmed.

That doesn't look like marine grade plywood I pulled out. There is a thick fiberglass layer between the plywood, did they lay new cheap plywood over the original interior skin?

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Fuzz
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Re: Radon Transom Replacement

Post by Fuzz »

Sorry about the transom but now is the time to fix it. There is both good news and bad. The good is there is nothing to complicated about what you need to do. The bad is it is nothing but pure old manual labour.
I do not think that little notch in the stringers is a big deal that close to the transom. You will need to cut the stringers back about a foot or so and that will let you get a good look at the stringers.
You spoke earlier about maybe going to a bracket at some point in the future. A transom built for an I/O does not need to be as tough as one for a bracket does as the thrust is placed a little different. I think I would go ahead and build the transom strong enough to hold a bracket just in case you go that way in the future. You said Radon is putting brackets on their boats now so I would give them a call and see what they say it needs.

bigtalljv
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Re: Radon Transom Replacement

Post by bigtalljv »

We think alike, I was going to build and outboard capable transom. I would imagine that 2x3/4” should be plenty, that’s almost 2” when done, but I’ll try to give them a call.

I just went out and started digging and solved some of my confusion about the outside skin. It’s 1/2” thick of solid fiberglass. I mistook it for more plywood. I ordered a sawzall, figured it was time to own one.

Fuzz
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Re: Radon Transom Replacement

Post by Fuzz »

With that much outside skin you sure do not need to add to it. That is a big time and cost savings. As for tools hammer, pry bars, big hammer circular saw all came in handy. The one tool that was a must have is a multi-tool. I know some folks do not love them but I would not do this kind of work with out one. If you do buy one get a heavy duty one. I am real happy with my Sonic Crafters, yes I have a couple of them.

bigtalljv
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Re: Radon Transom Replacement

Post by bigtalljv »

Yep, I’m multi tool guy. Just spent a few hours digging in the boat with it. I have a Fein, great tool.

It looks like originally they had a layer of plywood and then an inside layer of fiberglass. Although didn’t some people sandwich a layer of fiberglass between two layers of plywood? It’s 1/2” outside skin, plywood, thick layer of fiberglass, plywood, thin fiberglass. That what I saw.

I’m tempted to go with what was there, 2x3/4” plywood. They would certainly cover anything I ever wanted to hang on there.

Next bad news is the next bulkhead on the others side of the engine compartment has a big part of it that wet and rotten. I’ll just keep working my way forward.....

Jason

Fuzz
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Re: Radon Transom Replacement

Post by Fuzz »

With a half inch of outside skin you have a fine start. If you are going to install the plywood with epoxy I would skip the glass in the middle. It is the outside skins that are carrying the loads. The glass in the middle is doing almost nothing.
Sounds like you are going to need to bite the bullet and get serious about cutting stuff out. It will come apart pretty quick if you forget the subtle stuff :wink:

Fuzz
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Re: Radon Transom Replacement

Post by Fuzz »

I have talked about these before but when you get to the grinding part give these a try. https://www.toolocity.com/ZEC-grinding-wheels.aspx
They make them for a 4.5 inch grinder or a 7 inch one. You need to be covered up in PPE and ready to make a ton of dust but they move glass faster than anything I have ever used. But be warned this is a WMD so use it carefully.

bigtalljv
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Re: Radon Transom Replacement

Post by bigtalljv »

Yep, familiar with flap wheels. I used them in welding and on my zodiac refurb. Like my neighbor says about his big tractor and flail mower, an instrument of destruction. Either destroying things around it or itself.

So bill if materials. I’ve been catching up on reading transom replacement threads. So I think I’ll need:

Plywood
12oz biaxial cloth (enough for 5 layers)
12oz 6” biaxial tape (100 yards)
6 gallons of epoxy (more projects to come)
All the other accessories, probably need more wood flour, rollers, and the like.

What would my tabbing schedule be? I’m good with removing and replacing the plywood and glassing the large surfaces, the tabbing is new to me.

bigtalljv
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Re: Radon Transom Replacement

Post by bigtalljv »

For the 1000th time. If I used foam in the transom instead of plywood could I do one layer of 1.5” of the Glass Reinforced Polyurethane transom foam?

Its 50% more cost but it might be worth it to me. Unfortunately the best reason is to tell people it wasn’t replaced with plywood.

fallguy1000
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Re: Radon Transom Replacement

Post by fallguy1000 »

bigtalljv wrote: Sat Jun 01, 2019 1:18 pm For the 1000th time. If I used foam in the transom instead of plywood could I do one layer of 1.5” of the Glass Reinforced Polyurethane transom foam?

Its 50% more cost but it might be worth it to me. Unfortunately the best reason is to tell people it wasn’t replaced with plywood.
Not sure why not.

Not sure why you open with that line either.

It'd help if you link to the product.

Also, does the engine hang off the transom like the Bayliners or sit on engine bed?
My boat build is here -------->

viewtopic.php?f=12&t=62495

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