# Transom wood



## turkeyt (Apr 13, 2006)

Can anyone tell me what is the best plywood for transoms and who carries it for transom replacement? Looking for a supplier in Ohio Thanks guys


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## UFM82 (Apr 6, 2004)

I used 3/4" birch, 3 coats of satin polyurethane (sanded between coats) and a final coat of gloss poly. Made sure to seal the holes when I bolted it onto the transom. It looked great for the next 4 years and still looked great when I sold the boat. Ran me about $60 for the wood and poly. Worked great.


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## capt j-rod (Feb 14, 2008)

Plywood is a very generic term. Menards will sell marine plywood, but you are looking for the right glue with the fewest voids. Homestead hardwoods has some premium stuff at a premium price. What I do is buy menards and soak it with two heavy coats of CPES smith's sealer. I have done a lot of repairs to many boats and this stuff is the ticket. Soak it in and glue pieces together with 3m 5200. It ain't cheap, but it is the right way to do it.
http://www.smithandcompany.org/CPES/
http://www.rotdoctor.com/products/cpes.html


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## slimdaddy45 (Aug 27, 2007)

Menards has marine plywood 3/4'' is 70 and 1/2'' is 50 just bought some to replace my transom with I glued mine together with titebond II iglue and gonna seal with fiberglass mat with poly resin then glass it my boat with mat and 1708 fiberglass mine is fiberglass tho


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## slimdaddy45 (Aug 27, 2007)

You can also use just exterior plywood it has waterproof glue in it also but has alot of voids in it and knots marine doesnt have that


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## MassillonBuckeye (May 3, 2010)

slimdaddy45 said:


> Menards has marine plywood 3/4'' is 70 and 1/2'' is 50 just bought some to replace my transom with I glued mine together with titebond II iglue and gonna seal with fiberglass mat with poly resin then glass it my boat with mat and 1708 fiberglass mine is fiberglass tho


I used 2 pieces of 3/4" sandwiched. I bonded mine with tightbond II as well and nailed it together then stacked a bunch of wood on top while drying. Then coated everything in a couple coats of 2 part epoxy then painted. Pre-drill the holes slightly bigger so you can seal those as well. I couldn't do mine in fiberglass as it had to fit back into the aluminum skin and the tolerances were pretty tight. The wood I pulled out of there was only marine grade with a coat of paint. Nothing fancy. Lasted 30 years. Well more like 20 probably because it was pretty rotten lol. I'm guessing this is going to last at least another 20 hopefully more.

Really depends on your transom what all will go into it.


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## MassillonBuckeye (May 3, 2010)

slimdaddy45 said:


> You can also use just exterior plywood it has waterproof glue in it also but has alot of voids in it and knots marine doesnt have that


You have to be careful as some treated plywoods have copper which theoretically can react to dissimilar metals and cause corrosion. Heres a good write-up from another website(using the googler).

Re: Can pressure treated plywood be used for transom

I posted this a while ago, worth repeating. Does not address reactions though

From the web.... worth reading 

Marine Grade or Pressure Treated: The Facts

" Wood is good" unless it fails to serve the purpose for which it is intended To understand the differences between grades of plywood, and the meaning of the various designations, is to choose wisely and appropriately. The saying " Be fooled at your peril" applies to many things, but when considering the construction and end uses of various types of plywood, if you are fooled into using the wrong grade, the results can be unnecessarily expensive, or even disastrous. . 

Pressure-treated plywood, often called "Wolmanized" or P.T. plywood, is NOT " Marine grade" plywood, and those designations do not make the two products arbitrarily interchangeable. 
Pressure treated plywood is common plywood that has been subjected to pressure treatment with chemicals to prevent the wood from decaying, or rotting. To some degree, it also discourages insect damage because of the chemicals involved . Pressure treated plywood, however, is not suitable for marine use. The treatment of plywood with copper and arsenic compounds under pressure simply does not make the plywood waterproof, and worse, continuous exposure to water will leach the preservative chemicals from the pressure-treated wood. 
Again, pressure treated plywood is ordinary, interior-grade plywood that has been chemically-treated, and it is often made with softer woods to enable the penetration of the wood treating chemicals, with no special care effected to eliminate all gaps or voids.

G1S plywood, (good-one-side) is plywood with one side graded "Select" to show no defects or gaps and is an aesthetic consideration. 

Exterior grade plywood is made with water-resistant glue, but the exterior shell is the only layer that is made void-free. There may be gaps, voids and the resulting points of weakness in the interior layers. When you cut a sheet of exterior grade plywood, you may expose a gap on the cut surface. 

Marine grade plywood, on the other hand, is a different creature. Marine grade plywood is assembled gap and void-free in all layers, and laminated together with special, water-proof glue that holds the various layers together. When immersed, water has absolutely no effect on the glue or the strength of the lamination of marine grade plywood. Marine grade plywood will not commonly delaminate, bubble, buckle, or warp. Upon cutting marine grade plywood, no voids will be discovered on the cut edges. It is also usually constructed of harder woods such as Douglas Fir, or Western Larch. 
Marine grade is a superior grade of plywood, and a substantially better product. 

Do choose carefully when selecting plywood for marine use. Although it is more expensive, marine-grade plywood, when finished appropriately, will outlast pressure-treated plywood by far. The ordinary glues used in plywood , pressure-treated or not, will eventually fail for structural reasons. 

When the transom on your boat fails in the middle of the lake, the wisdom of having saved fifty dollars by buying cheaper pressure-treated plywood instead of marine grade will come to question rather quickly. In this application, and other critical structural applications, let us suggest that "the RIGHT wood IS good", and marine grade is best.


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## capt j-rod (Feb 14, 2008)

Titebond 3 is supposed to perform even better. I use penetrating epoxy to avoid greenhousing the wood. That meaning you tried for water tight, it got water in, and now it can't get out. Good tips on the pressure treated ply above. Read about the CPES in the links... It is expensive, but I swear by it! I use it everywhere including on my camper, my porch posts, transoms, cedar strip boats, Lymans, outdoor wood furniture. My cutting board for walleye is a scrap that I treated. It leans against the shed year round and looks amazing.


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## Popspastime (Apr 1, 2014)

recycled plastic 3/4" sheets 4x8 or 2x8 pieces available. I would never ever replace with more rot-wood ply. Work it like wood and glass it in.. done.


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## MassillonBuckeye (May 3, 2010)

Popspastime said:


> recycled plastic 3/4" sheets 4x8 or 2x8 pieces available. I would never ever replace with more rot-wood ply. Work it like wood and glass it in.. done.


Interesting. I'm curious as to where one might get sheets of solid plastic that big? Cost? Weight? I like the recycled idea.


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## bridgeman (Aug 26, 2010)

How long do you want it to last??? I chose 2 plies of meranti sealed with 3 coats of an epoxy resin. Most likely will outlast me. If your using the boat on a small lake and have a 9.9 hung on it about any plywood will do. If you 20 miles out on Erie and there some storm clouds heading your way you'll be glad you splurged and spent the extra 60.00 for a strong grade of plywood. Its amazing how much stronger this stuff is when compared to cdx, I bought from these guys a couple of years ago..

Homestead hardwoods just outside of Sandusky OH
http://www.marine-plywood.us/mahogany_meranti.htm


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## I Fish (Sep 24, 2008)

Good info, MassillonBuckeye. That article should be a sticky at the top. It seems this gets hashed out a few times a year. I used to have a piece of 3/4" marine grade plywood that I put under my trailer jack. I used for probably 10 years and it showed no signs of rot or delamination. I'd probably still be using it but I lost it.

I always recommend this, but, almost nobody ever does it. If you are looking to keep the boat long term, check out Coosa Board Blue Water 26. It's a composite, it's expensive, but, you don't have to seal it, just cut to fit and drop in, and it's got a warranty of 50 years. I cut my transom out of one sheet, and glued them together with 3M 5200. Now, if my transom ever gets wet, I don't care, and I have no worries of rot.

If you go with Marine grade ply, check out Home Depot. The last I checked they had the best price and availability. A 4x8 sheet of 3/4" 7 ply was $45.


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## Popspastime (Apr 1, 2014)

I Fish said:


> Good info, MassillonBuckeye. That article should be a sticky at the top. It seems this gets hashed out a few times a year. I used to have a piece of 3/4" marine grade plywood that I put under my trailer jack. I used for probably 10 years and it showed no signs of rot or delamination. I'd probably still be using it but I lost it.
> 
> I always recommend this, but, almost nobody ever does it. If you are looking to keep the boat long term, check out Coosa Board Blue Water 26. It's a composite, it's expensive, but, you don't have to seal it, just cut to fit and drop in, and it's got a warranty of 50 years. I cut my transom out of one sheet, and glued them together with 3M 5200. Now, if my transom ever gets wet, I don't care, and I have no worries of rot.
> 
> If you go with Marine grade ply, check out Home Depot. The last I checked they had the best price and availability. A 4x8 sheet of 3/4" 7 ply was $45.


Exactly..! Fix once and forever done. Last I priced the composite I think is was around $200 a 4x8 sheet but... faster, cleaner, rot-proof without all the sealing and painting.


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## trekker (Feb 18, 2013)

Marine ply with 2 coats of epoxy. Done right it will last for a very long time.


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## sherman51 (Apr 12, 2011)

if you only want to do it once and plan on keeping the boat for many many yrs the extra expense of the composite would be well worth it. if you want it to last 20+ yrs marine grade plywood sealed good will a good sealer should work just great. I have an old 86 cobia that's still solid after 30 yrs on the water with the original transom. so doing it right with marine plywood will last as long as most people will keep a boat.
sherman


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## turkeyt (Apr 13, 2006)

Thanks for all of the good replies


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## I Fish (Sep 24, 2008)

sherman51 said:


> if you only want to do it once and plan on keeping the boat for many many yrs the extra expense of the composite would be well worth it. if you want it to last 20+ yrs marine grade plywood sealed good will a good sealer should work just great. I have an old 86 cobia that's still solid after 30 yrs on the water with the original transom. so doing it right with marine plywood will last as long as most people will keep a boat.
> sherman


That's true. The thing is, all it takes is a screw hole to leak, get the water in there, and you've got another rotten transom, regardless of how well it was done to begin with. You've got none of those worries with composite.


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## nijajordan (Feb 5, 2013)

I'm about to do my transom, I'm going with marine grade plywood. Dose it need stained or painted. What type of resin is good to use. Can the resin be painted over.


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## bridgeman (Aug 26, 2010)

West Marine epoxy resin. 3 coats and you'll be good to go. Not terribly expensive


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## ssv1761982 (Jun 2, 2004)

What kind of boat? Fiberglass boat where it is all glassed in or aluminum boat with exposed wood?


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## nijajordan (Feb 5, 2013)

Aluminum with exposed wood. I like to pain too.


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## nijajordan (Feb 5, 2013)

It's a 16 ft Grumman GSF. I most likely will only hang a 9.9 on it but possibly go up to 15 hp someday.


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## capt j-rod (Feb 14, 2008)

Penetrating epoxy goes into the wood. Fiberglass resin laminates the wood. I would apply three coats of penetrating epoxy and then paint it what ever color you choose.


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## surffishn (Jan 20, 2010)

Seacast is the only way to go. No more problems with rotten wood.


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## nijajordan (Feb 5, 2013)

What's a good penetrating epoxy to use. I think seacast will be too pricey.


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## capt j-rod (Feb 14, 2008)

CPES is what I use. It's not cheap either but you get what you pay for. It's one of those jobs that you never want to do again


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## ssv1761982 (Jun 2, 2004)

I would just go with good outdoor plywood and put a couple coats of whatever you like on it. Look how long the original lasted. You aren't going to be stressing it so I wouldn't overthink it.


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