Smith's CPES over exterior plywood instead of marine plywood.

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wildvortex

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I have read all about how exterior grade plywood will work in a redecking application but I am thinking about going a step further and applying a coat of CPES over the entire piece prior to laying my glass. Has anyone done this? Is it recommeneded?
 
jigngrub

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Re: Smith's CPES over exterior plywood instead of marine plywood.

A lot of people coat their decking with epoxy before installing it, and a lot of members recommend it.
 
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wildvortex

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Re: Smith's CPES over exterior plywood instead of marine plywood.

Was planning on doing this as well as adding glass and resin
 
jigngrub

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Re: Smith's CPES over exterior plywood instead of marine plywood.

They also do that around here too.
 
BobSim

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Re: Smith's CPES over exterior plywood instead of marine plywood.

The Smith's is great stuff but I would hesitate before using it to treat new deck plywood. First let me say you will need a respirator and organic filters for it. Seriously, the fumes are bad. The first time I used the product I was dizzy, had headaches and an awful taste in my mouth for a couple of days. That was an outdoor application and I didn't think I needed the respirator. The CPES is not compatible with all epoxies and resins - if it doesn't stick to whatever you're using for the deck cloth/mat it would be bad. I would suggest thinning whatever brand of epoxy you use and encapsulating the material. Acetone and denatured alcohol are common but I would contact your supplier to verify. If you really want to get the most penetration for your buck then put the material in the sun, let it get as warm as possible and move it into the shade for the coating. The material will cool and draw the epoxy in.

CPES is a great product I am not slighting it in the least, but for this application I would do my homework. The folks at Smith's are very helpful, shoot them an email and ask what they think and if their product is compatible with yours. Hope that helps.
 
Ciera2450

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Re: Smith's CPES over exterior plywood instead of marine plywood.

If your sealing everything in glass and resin, you shouldn't have a need for the CPES.
Seal everything up good and you won't have problems. Something to be said for OVERKILL.

Just My .02
 
Grandad

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Re: Smith's CPES over exterior plywood instead of marine plywood.

The title of this thread implies that you're considering treating exterior plywood as a substitute for marine plywood. As I understand it, marine plywood will rot the same as exterior plywood. The reason for using it is that it has no voids in the layers making the sandwich stronger. So if you're constructing a transom or other structural parts, use marine ply, but you can save a few bucks using exterior grade for other things, if it's strong enough for your needs. Both need to be sealed or protected. - Grandad
 
Woodonglass

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Re: Smith's CPES over exterior plywood instead of marine plywood.

If you are re-decking your boat and are considering using Ext. grade ply wood, and you want to use epoxy I HIGHLY recommend you DO NOT use CPES. It is BASICALLY CRAP!!!! Our Local expert on Epoxy, Ondarvr, who has 40 yrs experience in the mfg and application of Epoxy in the boating industry will tell you so and has argued this point "ad infinitum" here on the Forum. Chemically Thinned Epoxy (That's what CPES is) weakens the produce and renders it pretty much useless. Now the MFG's of the product will try and tell you different but Ondarvr has the facts to back it up. The other point I'd like to make is the use of epoxy is NOT required for decking your boat. Regular Laminating Polyester Resin and Chopped Strand Mat will yield a great deck. It IS a little more of a hassle to have to lay the mat into the resin than to just paint the epoxy resin on but Epoxy is almost double the cost so you PAY for that convenience. It's your boat and your decision. Just wanted you to have all the facts. Here's a drawing of how to do a deck using Poly resin and Mat.

(Click the Pic to Enlarge)

Decks.jpg
 
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wildvortex

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Re: Smith's CPES over exterior plywood instead of marine plywood.

Thank you everyone, I have already sent a message to jamestown distributors and have yet to get a reply. I already have 2 quarts of CPES So I may use that on the verticals and just glass the decking. I simply do not want to have to go through this process again with this boat. Fortunatly the transom Is solid so I am just looking at redecking. Then again you never know what you are in for until you just get into it!
 
jigngrub

jigngrub

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Re: Smith's CPES over exterior plywood instead of marine plywood.

wildvortex said:
Thank you everyone, I have already sent a message to jamestown distributors and have yet to get a reply. I already have 2 quarts of CPES So I may use that on the verticals and just glass the decking. I simply do not want to have to go through this process again with this boat. Fortunatly the transom Is solid so I am just looking at redecking. Then again you never know what you are in for until you just get into it!
Click to expand...

If you don't want to have to deck your boat again I suggest the CCa treated plywood.

http://www.pontoonstuff.com/pontoon-boat/144-marine-plywood.asp


If the rotten decking that you pulled out of your boat was glassed in, that should tell you something.
 
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74bayliner

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Re: Smith's CPES over exterior plywood instead of marine plywood.

Wood on glass, I dont mean to hijack the thread. I just was wondering. by your model of how to fiberglass the deck...
Is my model correct? will that 1 roll of fiberglass 3' x 180' be enough?
or do i need more rolls.. just for the decking alone. its 1.5oz CSM.
CSM.JPG

EDIT: and my sketches are very rough... so please dont pay attention to detail. just the numbers. i wanna be sure before i purchase the mat

its $1.75 per linear yard for 38" (3' roughly) if i pick it up
its $2.50 per linear yard for 38" (3' roughly) with shipping

Also thats a pretty good deal i think considering its $141 on uscomposities.. and that is without shippin :)
 
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wildvortex

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Re: Smith's CPES over exterior plywood instead of marine plywood.

74, you will probably be cutting it close. one thing that I know from experiance is that when you think you will be just redecking chances are you will be in for a full restore. see what I ran into http://forums.iboats.com/showthread.php?t=510588. I would say start with a roll and if more is needed then order or pick up more. that is what i did.
 
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74bayliner

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Re: Smith's CPES over exterior plywood instead of marine plywood.

I will probably be cutting close but if i need to I can than buy more CSM instead of 60 yards , i could by 20 for 40 bucks or what not. But i see your post. very nice boat i am going to post a question onto that post if you can take a look at it.
 
Woodonglass

Woodonglass

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Re: Smith's CPES over exterior plywood instead of marine plywood.

Did you get my PM??
 
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74bayliner

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Re: Smith's CPES over exterior plywood instead of marine plywood.

Yes, woodonglass i did get your PM, i sent you one back... I think. I have never PM'd anyone in my life .Thank you so much, your very helpful :)
 
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