# marine grade plywood



## txneal (Mar 15, 2010)

Several months ago, I had located a place online that was selling marine grade plywood by the square foot. I've searched again and now I can't seem to locate them again. I only need a small amount of plywood for my transom, so I don't want to order an entire sheet. Do any of you guys happen to know where I can order smaller pieces of marine grade plywood? Any assistance with this would be a huge help as I live a few hundred miles from any retail stores that might sell it. Thanks!


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## 1448Tom (Mar 17, 2010)

txneal, I just purchased a new Crestliner 1448 jon boat. I am going to deck-out the boat. The dealer recommended I treat my wood with MinWax, "Spar Urethane". You can purchase a quart at Home Depot for $14 and some change. I checked Lowe's first, they did not have MinWax Spar Urethane. For best results:


Apply a thin coat
Let dry for at least 6 hours
Lightly sand with 220 sand paper
Apply second coat

For the transom wood, I would apply at least 3 coats. Spar Urethane will not cause corrosion, or pitting like the treated plywood at lumber dealers. Yesterday, I treated all of the wood for my frame. I am getting ready to sand it and apply second coat. Today, I'm also applying MinWax, Spar Urethane to my plywood.


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## Rat (Mar 17, 2010)

The only place I know of that sells plywood by the square foot is buckwoodcraft.com and I think they have a minimum order, but I can't remember. 

Here it is:
buckwoodcraft.com
It isn't marine grade, it is a veneer, do not use it in your transom. Use good exterior grade ply or a real marine grade ply. Using a unknown grade of veneer is asking for trouble. Your transom needs to be strong, don't try and skimp on the wood, buy good wood. And it doesn't matter what plywood you use it all needs to be treated for protection; either Thompson's-like water seal, Spar Urethane or Epoxy.


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## lckstckn2smknbrls (Mar 17, 2010)

I used a good exterior plywood.


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## dyeguy1212 (Mar 17, 2010)

lckstckn2smknbrls said:


> I used a good exterior plywood.



So did everyone else on the site :lol: OP, I don't know if you have your heart set on marine grade plywood, but you can save a lot of dough by buying exterior grade, nontreated wood and watersealing it yourself.


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## ppettit (Mar 17, 2010)

Hello All,
I just signed up to your forum today. I've been reading the post for awhile, and enjoy watching all these boats get fixed up. 

So you guys would recommend Spar Urethane on Marine Grade plywood as well? This won't leach into the carpet or cause any problems against foam? I'm replacing a bass tracker floor and redoing the carpet.


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## dyeguy1212 (Mar 17, 2010)

This is the first time I've seen Spar Urethane pop up on these boards before, so I'm not sure many people will be able to chime in.


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## Rat (Mar 18, 2010)

ppettit said:


> Hello All,
> I just signed up to your forum today. I've been reading the post for awhile, and enjoy watching all these boats get fixed up.
> 
> So you guys would recommend Spar Urethane on Marine Grade plywood as well? This won't leach into the carpet or cause any problems against foam? I'm replacing a bass tracker floor and redoing the carpet.



Spar Varnish has been around for a long time and works pretty well. Some Spar Varnishes, but not all, have UV inhibitors; many will need to be sanded and reapplied, or re-coated, every few years. Using a paint over spar varnish has best results as almost all outdoor paints have good UV inhibitors. This way you can use a less expensive "porch paint" but still have good weather proofing and elasticity with the spar varnish. Carpet will also block UV degradation of the Spar varnish. 

Spar Varnish is a very good choice for protecting wood that you want to leave brite finish on, IOW see the wood grain/pattern. 

Spar varnish, or any other weatherproofing product, should not leech into the carpet once applied; just let it cure the right amount of time. It will also not react with the foam, again, just let everything cure before placing the different products into contact with each other. 

I don't know if I would necessarily recommend it for your application, but it will work. Like all things concerning boats; weatherproofing is a compromise and, largely, a personal decision based on the final look you want on the hull and how much you are budgeting. 

Good Epoxy will never allow water intrusion, put you need to be careful of penetrations (Screws, staples etc), it needs to be painted or pigmented for UV inhibition, it is more expensive but durable and has a nice finish.

Poly and Vinyl-ester resins are cheaper but allow water intrusion but otherwise are similar to Epoxy resin, best over composites not wood.

Thompson's-like water proofing is cheap and works well, but doesn't last as long as epoxy resin and you still need to be careful with penetrations and eventually it will need to be reapplied. How long? Maybe 10 years if taken care of I guess. 

Outdoor paint, porch paint, will protect wood to a good degree; it is cheap, easily applied and easily found. It's not very durable and will need to be touched up, repaired or reapplied yearly. Many homebuilt row boats only have this as a protectant. 

Topside coatings, like paint, steelflex or durabak, are designed to go over the sealant coating and are not very good as a stand alone sealant on wood; but are very good over metal and composites. They are durable, expensive and have a nice finish.


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## Jim (Mar 18, 2010)

Skip the marine grade plywood and use regular plywood. It could cause corrosion issues down the line.


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## Rat (Mar 18, 2010)

Jim said:


> Skip the marine grade plywood and use regular plywood. It could cause corrosion issues down the line.



Marine Grade ply causes corrosion? 

I think Jim is thinking treated ply. Marine ply, 1088 and 6566 grade, are not chemically treated and will not cause corrosion in an Alu. hull. They are simply a high grade hardwood ply, with no voids, more laminations per sheet and a glue that is water rated.


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## txneal (Mar 18, 2010)

Thanks for all of your input. Yes, I pretty much have my heart set on using marine grade plywood. It is quite expensive, but the high price is for a reason....it is made of hardwood, has no voids, and the glue is rated to hold up under water. The transom that is currently on my boat is reinforced with marine grade plywood and has held up excellently for almost 40 years. However, after this much time, it is worn enough that I would like to replace it. I have inquired about purchasing some locally, but my only nearby lumber yard says it is a special order and will cost me about $175 to get a sheet delivered to their store. Like I said, I only need a small piece, so I will continue searching. It was less than a year ago that I saw a place online that was offering it for sale by the square foot, but now I can't relocate that website. I'll keep searching and will keep an eye on this thread in case anybody else may know of a source.


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## russ010 (Mar 18, 2010)

I just did a quick search, but I don't know if any of these are the sites you were referring to

1. https://www.buckwoodcraft.com/king_starboard_order_page_square_foot.htm

2. https://marine-plywood.us/douglas fir.htm

3. https://www.nauticallumber.com/inde...Path=2&zenid=102626de5a86aee55d2ee1017bff5936


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## ppettit (Mar 19, 2010)

Thanks for the info. I have a bunch of random sealers i need to use up , polyurethane and spar varnish mostly. If i had it to do over again for this particular project i don't think i would have spent the money on marine grade. The foam in the bottom probably needs replacing ..but that will be a good project for next winter. Right now i just want to get the carpet done, build a new console, and go fishing.


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## russ010 (Mar 19, 2010)

Rat said:


> Jim said:
> 
> 
> > Skip the marine grade plywood and use regular plywood. It could cause corrosion issues down the line.
> ...



Actually, Jim is right... some marine grade plywood IS treated with chemicals.. this is what a lot of the big wood boat builders use - no tin in their boats

https://marine-plywood.us/douglas fir.htm#BC_Pressure


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## Rat (Mar 19, 2010)

Okay, that's TREATED Marine Ply. I had no idea and have never seen it...

And I see it is still listed as CCA treated as well not ACQ and CBA treated, they must have a lot of old stock to get rid of or they haven't updated their site. I don't know why you would need treated lumber on a boat; are there swimming termites? Seems to me treating it just makes it heavier and more expensive.


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## txneal (Mar 20, 2010)

Thanks for the links, Russ. I had already seen two of them, but I'm still not finding any option to order anything other than a full sheet. I really have no use for a full sheet, so I'm trying to find a place where I can order something like a 2'x2' piece. I had located such a source once, but I'm unable to find it now. I live in a desert and have to drive a fairly long distance just to get my boat into the water. Therefore, there are no nearby location to purchase any marine plywood. I can't even find spar varnish within 200 miles of here! I can continue to use my boat with the transom as it is, but would like to get this replaced asap, so I'll keep looking. I do have a friend who is going to be doing some major reconstruction of his sailboat soon, so maybe he'll have an extra piece I can use.


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## huntinfool (Mar 20, 2010)

I do fiberglass repairs for a living and I have done so many transoms I can't even remember how many. 

If your not concerned with the price then you can use marine ply. 

I do not. 

I would use a treated ply and I would wrap two 1.5oz. mats over the ply and install that. You will not get water intrusion. Epoxy is twice the price of polyester resin. If you know what your doing, or just take your time you can have a transom that will last a lifetime. However anywhere you put a screw in the transom is going to be a place that water can enter the wood. 

Everyone has a different way to do the same thing, this is just my method and it works great for me. 

Now if you really want a transom that will last a lifetime, then pour a solid glass transom. I do those on all fiberglass boats and some aluminum boats.


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## LarryA (Mar 20, 2010)

I used marine grade on my boat transom and had to buy a full sheet so I could double it to get the required thickness.
I found a local lumber place that would sell retail and that was the only one within a reasonable distance.


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## aaronthetaxidermist (Mar 20, 2010)

I talked with the local home improvement/lumber yard chain ( Menards)....they could order in 3/4" marine grade for $60.00 a sheet, no min. quantities. 

I think I am going to go with standard 3/4 in. though...I will probably be replacing it every couple of years anyway( my boat gets a lot of abuse between fishing , trapping, dogs, and duck hunting ).


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## 1448Tom (Mar 21, 2010)

ppettit said:


> Hello All,
> I just signed up to your forum today. I've been reading the post for awhile, and enjoy watching all these boats get fixed up.
> 
> So you guys would recommend Spar Urethane on Marine Grade plywood as well? This won't leach into the carpet or cause any problems against foam? I'm replacing a bass tracker floor and redoing the carpet.



I treated all of my frame lumber, and my regular plywood with Spar Urethane, apply according to directions. I applied two coats to each piece, or section of lumber, lightly sanding with 220 sandpaper after the first coat. Spar urethane is what the boat dealer recommend I use. He said it's used on the wooden support pole of sailboats.* Noun: spar...A stout rounded pole of wood or metal used to support rigging.* It does have UV inhibitors. According to the label, MINWAX Spar Urethane has exceptional protection from Sunlight, Rain & Moisture, and Temperature Changes.

I used it because it was dealer recommended. Before laying your carpet, lightly sand the up-side of the floor with 220 sandpaper so the adhesive will adhere to the wood, and the carpet will adhere to the adhesive. I assume once applied by label directions, it shouldn't leach into your carpet once it dries as instructed.

Good luck

-1448Tom


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## Rat (Mar 21, 2010)

huntinfool said:


> I would use a treated ply and I would wrap ...


Why treated huntinfool?


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## Mike Redmond (Mar 21, 2010)

Been building fishing boats as a hobby for the last 15 years,have yet to see treated marine ply,,,I beleive it would interfere with the epoxy you generally use to make joints, and seal up the wood with a first coat of epoxy wich is pretty much the standard right now,,,all on depending how long you want that wooden boat to last


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## huntinfool (Mar 21, 2010)

Rat said:


> huntinfool said:
> 
> 
> > I would use a treated ply and I would wrap ...
> ...


In the event that you don't get the glass sealed around the wood good enough it will last much longer than regular ply. I have some wooden transom's out there that are going on 15-20 years. But now we only do glass transom's. Money wise they are about the same, but glass transom's are much easier.


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