Marine plywood for transom

[crw1957]

Can you suggest any sources for 1 1/4" marine grade plywood? I need a piece for a transom.

 

[leisjohn]

Re: Marine plywood for transom

I used 2 pieces of 3/4 AB exterior with 1708 in between them, it made turned out great. What size boat are you working on.

 

[Sparkler]

Re: Marine plywood for transom

I used 2 pieces of 3/4 AB glued and screwed. Finished it with a good marine grade varnish and it turned out very nice. It was a fun project.

 

[Mark42]

Re: Marine plywood for transom

For a transom I would use pressure treated. Why go to all that work and expense and then have it ruined by a leak?

Take note that marine grade plywood is a high quality ply with fewer/smaller voids and more and thinner plies than regular CDX. But it has NO anti-rot treatment. For that, go with pressure treated. In fact, the APA suggests pressure treated ply in boat building. It would be my personal preference to use PT ply for the transom, stringers and decking. Others here dissagree, but the APA has done testing of resin on wet PT ply and it holds very well.

Read about why the APA says:

For BEST performance of plywood in boat manufacturing, APA recommends the use of treated plywood ...

Read all about it here: http://www.glen-l.com/wood-plywood/b...g-plywood.html​

Now if you want both Marine Grade and Pressure treated, Greenwood Products has been making marine pt ply for 20+ yrs. It is used in many production boats and there are zero bonding issues. Google a little on boat mfgs and see it in use...called XL.

 

[rucaradio]

Re: Marine plywood for transom

I just picked up a 4x8 sheet of 3/4" pressure treated for my transom.. $32.00 each at Lowes. It's odd how the pressure treating has a tendency to twist the wood. I found the straightest sheet, and hopefully it will even out after its laminated and installed.

 

[Mark42]

Re: Marine plywood for transom

I just picked up a 4x8 sheet of 3/4" pressure treated for my transom.. $32.00 each at Lowes. It's odd how the pressure treating has a tendency to twist the wood. I found the straightest sheet, and hopefully it will even out after its laminated and installed.

Even non-treated ply is warped. I picked up a piece of CDX last month from the lumber yard and the best they had were all "racked" like a potato chip. It's the nature of plywood.

If you have the space, nail or screw it to the bare wall joists in a garage or shed to dry for a week. When you glue up two pieces, be sure they are curved opposite and screw together until the resin or glue is set.

 

[halas]

Re: Marine plywood for transom

Treated is the way to go. I only used the regular because the lack of time to allow drying out the stuff.

 

[lakelover]

Re: Marine plywood for transom

I will be replacing a transom soon myself. Logically, I would automatically think pressure treated for a transom, but what about the issue of the chemicals corroding aluminum? Is is OK to use with aluminum? I've seen opinions both ways, but does anyone know of any research to back them up?

 

[Mark42]

Re: Marine plywood for transom

I think the latest cca treated ply is safe for aluminum. But you should check the tag stapled to each piece, some list "safe for aluminum". Call or look up the manufacturer on the web and find out what they say.

 

[Yacht Dr.]

Re: Marine plywood for transom

1957.. is there a reason you need 1 1/4" ?

If so then I would go with 5/8" marine grade with 1.5 oz mat/resin glue-bond.

YD.

 

[Bob_VT]

Re: Marine plywood for transom

I think the latest cca treated ply is safe for aluminum. But you should check the tag stapled to each piece, some list "safe for aluminum". Call or look up the manufacturer on the web and find out what they say.

Hmmmm they only sell ACQ around here which will react with aluminum and most fasteners

CCA was good but it could poison you

 

[Mark42]

Re: Marine plywood for transom

.....CCA was good but it could poison you

Hence the warning "Not to be taken internally" prominently displayed on each sheet of plywood.

I remember the rating used to be .40 cca, then it dropped to .25 cca, now I don't know what the rating is or how much it is.

 

[Bob_VT]

Re: Marine plywood for transom

Yup ..... saw a guy try to swallow a whole sheet once.... he was drunk!!

I don't get the choice is my point...... cca not available here.

 

[Mark42]

Re: Marine plywood for transom

Yup ..... saw a guy try to swallow a whole sheet once.... he was drunk!!

I don't get the choice is my point...... cca not available here.

It may not be available here either. I just haven't looked close at a label in a couple of years. But what ever it is, its probably not the good stuff!!! the .40 cca that I built my deck out of in 1995 is solid as can be today, and probably will be 10 years from now.

 

[NSBCraig]

Re: Marine plywood for transom

Marine ply can be pressure treated and the APA DOES NOT RECOMMEND you use regular PT.

Mark I just reported you again to TD stop lying to people!

 

[tashasdaddy]

Re: Marine plywood for transom

i still stand my ground that Pressure treated has no place in a boat. aluminum, or fiberglass.

 

[NSBCraig]

Re: Marine plywood for transom

For BEST performance of plywood in boat manufacturing, APA recommends the use of treated plywood according to the following specification.

Treated in accordance with AWPA Standard C9 with < CCA, ACQ, ACZA or ACA> to 0.40 pcf retention. Kiln dry after treating (KDAT) to 18% or less.


NOT Home Depot PT

It helps if you read the next sentence.

 

[Mark42]

Re: Marine plywood for transom

For BEST performance of plywood in boat manufacturing, APA recommends the use of treated plywood according to the following specification.

Treated in accordance with AWPA Standard C9 with < CCA, ACQ, ACZA or ACA> to 0.40 pcf retention. Kiln dry after treating (KDAT) to 18% or less.


NOT Home Depot PT

It helps if you read the next sentence.

Yep, that why I give them the link. So they can read the whole thing for themselves.

And what you can buy at a lumber yard IS " < CCA, ACQ, ACZA or ACA> to 0.40 pcf retention". It doesn't have to be kiln dried. There is nothing special about a kiln that letting it dry in your garage won't accomplish.

And exactly what part of my post is a lie? Maybe you can identify it for everyone here.

You sure turned out to be a weird kid.

Geeze, get a grip.

 

[Mark42]

Re: Marine plywood for transom

i still stand my ground that Pressure treated has no place in a boat. aluminum, or fiberglass.

You can stand your ground all day long. It doesn't make you correct. And the APA doesn't agree with you. How do you justify standing your ground when you know that the professionals who define the industry standards say that your position is wrong? I would really like for you to explain that, rather than just throw out an off hand statement about standing your ground.

 

[jonesg]

Re: Marine plywood for transom

zzzzzzzz