Which plywood to use for muffler mounting pad

boatrboy

Well-Known Member
Oct 3, 2006
1,839
Orange, CT
Boat Info
2006 340 Sundancer
Engines
Twin 8.1 Horizons with V-Drives
My port muffler mounting pad is soft in some spots from a water leak I am fixing. I was going to replace it and started looking at marine plywood but read that acx will do?

it’s a small piece 3/4” thick and 17” x 22”. I planned on using white bilge paint on it as that appears how it’s coated.

Starboard seems overkill and is soooo expensive in my opinion.

So what is a good plywood for this repair?

Mark
 
For that you could probably get away with regular plywood. But coat it twice in epoxy. Let the edges soak it up. Seal any mounting holes.
 
I was going to use Pettit bilge paint - not sure that is epoxy?
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I can tell you that the original one is not glass sealed and just looks like it’s painted plywood. It’s the same as all of my strainer mounts too which is why I assumed just plywood would suffice. Did you notice if yours are glassed?
No idea. But your first line says a lot: "My port muffler mounting pad is soft in some spots from a water leak I am fixing." Had it been sealed, it wouldn't have gotten soft. You could probably just use some painted plywood and be done with it. It will probably last as long as you own the boat.

But on my last boat, 1980 Chris Craft, every piece of wood I replaced was coated in epoxy resin -- better than original.
 
No idea. But your first line says a lot: "My port muffler mounting pad is soft in some spots from a water leak I am fixing." Had it been sealed, it wouldn't have gotten soft. You could probably just use some painted plywood and be done with it. It will probably last as long as you own the boat.

But on my last boat, 1980 Chris Craft, every piece of wood I replaced was coated in epoxy resin -- better than original.
I see where you are coming from - thanks
 
Your 270 seemed to be pristine, Just sayin.
Thanks for the compliment - this new to me boat is not up to my standards hence wanting to replace the that base. I was going to buy bilge paint and start trying to clean things up, or at least what I can get to without pulling the engine like I did on my 270. I thought painting the correct type plywood would be acceptable to me but you guys have me re-thinking :). Pricing out starboard now. I will have it routed out in the shop where I work with radius’s on what ever I decide on our cnc router.
 
I replace my battery shelf(s) with 3/4 ply with marine plywood. Painted with Total Boat gray bilge paint. That was 10yrs ago and now I am going to paint the bilge again. The shelves are still in perfect condition.
 
Starboard is horrible to bridge and mount things onto. It will start to deflect in no time at all. Plus, it is prone to mold and staining. You are better off with a marine grade plywood (CDX has external glue so that would work) as long as you seal it. The big difference between marine Ply and CDX is the voids and amount of ply's. The voids in CDX will make it hard to seal up. If you have fixed the source of water that created the problem then Plywood is where I'd land.
Everything in the Lazzarette on my boat is mounted on plywood decking; there has to be at least four sheets of the stuff back there all sealed with a gelcoat or something like that. I don't have any issues other than the quality of the finish.
 
If you do go with a CDX, do yourself a favor. I use CDX in construction a lot. The lowest cost ( I deal in many units of the stuff a month) and best I have found is from Home Depot. Not the stuff from the US (Yeah I know) but the stuff from Canada. It will say on the sheet and also has the blue/green edges. They don't use a regular glue but a UV cured glue and a higher pressure in the process. I have had a few scraps here at the house for projects and it sits outside. In Oregon. Where our state flower is moss. Our driveways are always a better green than the lawns. We can't tan, we rust. Not a single issue with it coming apart. But it has to be the stuff from Canada. And I have to say, I can't stand doing business with HD. They have ripped me off on orders of tens of thousands of dollars over the last couple of years.
 

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