Marine Grade Plywood alternatives

[yorktown mike]

I recently bought plywood at big box store for a home project, not impressed. Not only were there voids that you don't see until you cut it, but there were bulges on some sheets , I should have checked more carefully before bringing home. My advivce is to not get the cheapest option, and check each sheet carefullly. What I have found with my recent 14 ft Monark boat purchase is the little things add up quickly, nothing is cheap, welcome to boating!

 

[muskyhunter1978]

I recently bought plywood at big box store for a home project, not impressed. Not only were there voids that you don't see until you cut it, but there were bulges on some sheets , I should have checked more carefully before bringing home. My advivce is to not get the cheapest option, and check each sheet carefullly. What I have found with my recent 14 ft Monark boat purchase is the little things add up quickly, nothing is cheap, welcome to boating!

100%. I'm certainly not trying to cheap out, but I thought almost 200 bucks for a sheet of marine is nuts. Especially given the fact that I'll have to seal it with epoxy either way. I will be getting wood from a lumber yard and not the big box places, regardless. I almost said the heck with it and pulled the trigger on a sheet of coosa, which I know would be the ultimate fix for this thing.

 

[muskyhunter1978]

I went through this last summer at 170 for a sheet of 1/2 marine grade. I worried and researched and looked into composites and really worked myself up about it. In the end, I wrote the check and I wish I would have just done that to begin with. That stuff is sexy! If it's a boat your keeping, just get the good stuff and gripe about availability and cost from the captain's seat. I invested a lot of time I could have invested working on the boat. You've probably got bigger things to worry about.

That said, if it was a boat I didn't have heirloom kind of feelings for, BCX and Old Timer's Formula application method (boiled linseed oil, spar oil based urethane varnish, mineral spirits applied quite liberally) would be plenty good. The wood you selected is Exposure 1, waterproof bond, but not something to leave out unfinished. Well... marine ply as far as I know doesn't really want to be out uncovered either. I ended up putting over half a gallon of OTF over marine ply, and don't feel like I need to worry about it for a long time. Keeping it dry will make any wood last much longer.

Once you get past the wood choice, now you can agonize over the wood finish! (ie, epoxy or OTF).

Oh, and here's one thought I never finished when I was going through BCX, Marine grade, Composite, Epoxy, Spar mixture... modify some aluminum car ramps from Harbor Freight. I really know how spend time in the rabbit hole. That's why I say just get the marine grade and move on. You may not have this problem, but if I don't reel mine in, nothing ever gets finished! lol. Good luck!

Honestly thats the thing. The more I dig into this boat, the more I'm thinking this is a ten year plan and I'll most likely be buying another boat after that. I love the layout of this boat and for the most part, its in very nice shape for its year. But the flaws I'm finding, particularly corrosion, leans me in the direction of fixing it up to a solid functional boat to use for ten years or so, and then moving on to my next boat. This is why i'm leaning toward BCX/ACX and epoxying the thing and being done with it.

 

[yorktown mike]

100%. I'm certainly not trying to cheap out, but I thought almost 200 bucks for a sheet of marine is nuts. Especially given the fact that I'll have to seal it with epoxy either way. I will be getting wood from a lumber yard and not the big box places, regardless. I almost said the heck with it and pulled the trigger on a sheet of coosa, which I know would be the ultimate fix for this thing.

You are correct , 200 bucks is ridiculous! Good luck!

 

[farmer4life]

I struggled with this on my own build but ended up buying something similar to that Lowes product and I’m very happy with it.

The key as others have mentioned is sealing it. You still need to seal marine grade anyway. I used old timers to seal and topcoat with porch paint for the floor, and used the same stuff for my transom but topcoat with several coats of spar varnish.

My boat is no heirloom but the flour and transom are both solid. If you seal the plywood well, you’ll likely be ok with whatever plywood you have.

 

[SAABologist]

There is a lot of discussion about this on the forum. I think we tend to over think this and probably spend too much money and too much worrying about the plywood.

Yes, for our boats the marine plywood is just not worth it, in my opinion.

If you get B/C EXTerior plywood, not pressure treated, it is good enough to last for years if you prevent water from sitting in the boat while it's stored. My understanding from this forum is the glue is the same as marine grade but there are voids in the layers.

I used B/C EXT and then soaked it with epoxy resin cut with acetone. That was a recommendation found on this forum. It is a great idea and worked great. But I would not do it again. Why? Because for much less money and much greater ease you can treat the plywood with the Old Timer's formula that uses linseed oil. That would have been fine and so much faster and easier.

The other reason I would not treat the plywood with epoxy is because I covered the deck with marine vinyl. Because I had created an epoxy finish, I needed to use gallons of the very expensive contact cement. If it had been plywood with linseed oil I could have used the regular glue and saved $100s just on glue and it would have been so much easier.

In the end, the deck will last longer than I ever want to have this boat. And it would probably last the same if I had not done the full-blown epoxy treatment.

 

[muskyhunter1978]

Thanks again everyone. Really appreciate the insights and chat on these topics. I was able to find good qualtiy BCX locally here for 60 a sheet. I'll be able to build my transom core with one sheet. I am going to coat with penetrating epoxy as I already ordered it. Hopefully I will have enough left over from the kit, to drill and then fill each through bolt with the epoxy as well to ensure complete sealing.

This boat is 20 years old, she's been well taken care of for the most part, but one oversight (leaky bolts for a ladder) totally trashed the transom area. If I can build this old girl up and get another 10 years out of her, I'll be happy.

 

[SAABologist]

Thanks again everyone. Really appreciate the insights and chat on these topics. I was able to find good qualtiy BCX locally here for 60 a sheet. I'll be able to build my transom core with one sheet. I am going to coat with penetrating epoxy as I already ordered it. Hopefully I will have enough left over from the kit, to drill and then fill each through bolt with the epoxy as well to ensure complete sealing.

This boat is 20 years old, she's been well taken care of for the most part, but one oversight (leaky bolts for a ladder) totally trashed the transom area. If I can build this old girl up and get another 10 years out of her, I'll be happy.

Good decision! As you are only doing the transom, it does make sense to me to make it bullet-proof with the epoxy.

 

[ripdmup]

If I can build this old girl up and get another 10 years out of her, I'll be happy.

 

[muskyhunter1978]

Good decision! As you are only doing the transom, it does make sense to me to make it bullet-proof with the epoxy.

Yes... because I ain't doing this bullcrap again... lmao.

 

[LDUBS]

Thanks again everyone. Really appreciate the insights and chat on these topics. I was able to find good qualtiy BCX locally here for 60 a sheet. I'll be able to build my transom core with one sheet. I am going to coat with penetrating epoxy as I already ordered it. Hopefully I will have enough left over from the kit, to drill and then fill each through bolt with the epoxy as well to ensure complete sealing.

This boat is 20 years old, she's been well taken care of for the most part, but one oversight (leaky bolts for a ladder) totally trashed the transom area. If I can build this old girl up and get another 10 years out of her, I'll be happy.

If you are talking about filling oversized drilled holes with epoxy then re-drilling them (a best practice), a "penetrating epoxy" might not work for that. If you are talking about sealing the exposed plies after drilling through, then you are good.

 

[FuzzyGrub]

Thanks again everyone. Really appreciate the insights and chat on these topics. I was able to find good qualtiy BCX locally here for 60 a sheet. I'll be able to build my transom core with one sheet. I am going to coat with penetrating epoxy as I already ordered it. Hopefully I will have enough left over from the kit, to drill and then fill each through bolt with the epoxy as well to ensure complete sealing.

This boat is 20 years old, she's been well taken care of for the most part, but one oversight (leaky bolts for a ladder) totally trashed the transom area. If I can build this old girl up and get another 10 years out of her, I'll be happy.

In ten years, the transom will still be solid as a rock.

 

[muskyhunter1978]

If you are talking about filling oversized drilled holes with epoxy then re-drilling them (a best practice), a "penetrating epoxy" might not work for that. If you are talking about sealing the exposed plies after drilling through, then you are good.

good point. I guess I'll just drill and figure out the best way to thoroughly coat inside of the holes.

 

[muskyhunter1978]

In ten years, the transom will still be solid as a rock.

Thats the hope. And in ten years, if I still like the boat and everything else is still solid, I can keep rolling with her until I get wealthy enough to afford a nice new rig.

 

[Billyfish]

Some places you can get exterior or marine fir plywood at fair prices. That is my choice went budgeting. In Florida it’s expensive, we grow pine!

 

[Earl D]

I'm putting decking in my aluminum V-hull and instead of using wood, due to weight, I am using aluminum angle iron and PVC panels which come in 24" x 48" at 1/2" and 3/4" thick.

 

[thill]

Some places you can get exterior or marine fir plywood at fair prices. That is my choice when budgeting. In Florida it’s expensive, we grow pine!

SYP (Southern Yellow Pine) from FL is very strong and weather-resistant stuff.

Fir plywood is very good for soaking up waterproofing agents. That's why many quality marine plywoods are made from fir.

Regardless of type, I personally like soaking ply in Thompson's Wood Preserver, and have used it for many years with great success, but to each their own. As long as you use SOMETHING, it should last for a good number of years. \

I've yet to have any rot in a deck or transom I've done, even many years later.