Best kind of plywood?

Beeched

Petty Officer 2nd Class
Joined
Jun 22, 2002
Messages
110
Getting ready to rebuild the floor in my boat. The flooring that I took out is 1/2" and was very deteriorated. I am planning on putting in 3/4" for the strength. The difference in weight shouldn't create any problems. The main question is weather to get regular plywood or get pressure treated. Regular would have to be waterproofed in some way. Pressure treated contains chromiun-copper-arsenic. Will have my two dogs with me part of the time. When PT ply gets wet does it seep any of the chemicals? Is there any chance that any of the chemicals will interact with the aluminum and create any problems? At any rate I would like to have the best looking wood grain that I can get.
 
D

DJ

Guest
Re: Best kind of plywood?

Beeched,<br /><br />I am assuming you boat is fiberglass? I would not use pressure treated. Epoxy won't bond to it.<br /><br />If your boat is aluminum, I would use regular plywood and seal it with epoxy. I like West Systems epoxy for these types of projects.
 

Beeched

Petty Officer 2nd Class
Joined
Jun 22, 2002
Messages
110
Re: Best kind of plywood?

The boat is aluminum. "59" Crestliner 15'.
 

crab bait

Captain
Joined
Feb 5, 2002
Messages
3,831
Re: Best kind of plywood?

that PT plywood is some nasty stuff..<br />splinters, warps,shrinks, buckels...<br /><br />get ab doug fir exterior ply.. <br /><br />some what hard to find tho but worth it..<br />'big box home centers ' don't carry it..<br /><br />go to a good lumber yard.. they can get it with in a week.. then THIN epoxy the heck out off it .. 2 coats both sides & edges real good.. counter sink srcew heads & epoxy putty seal the heads..<br /><br />only thing that hurts epoxy is UV..<br /><br />must paint or marine varish to protect..
 

plywoody

Senior Chief Petty Officer
Joined
Aug 11, 2002
Messages
685
Re: Best kind of plywood?

If the plywood is going to be exposed, get marine grade Douglas fir plywood. It is as close to a solid piece of wood as you can get, as all defects, including in the inner plies, are removed, and it has a joined coreline so there are no gaps where water can collect. It is expensive, of course, but so is ABX plywood, and it is made for the application you are using it for (as opposed to ABX, which is primarily a face graded product suitable for cabinets and such)<br />Most major metropolitan areas have someone who carries marine grade-but you typically won't find it at your local lumber store--you will have to find a source.<br />I can get into all of the technical reasons why it is worth the extra cost if you wish--it is what I do for a living!
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,465
Re: Best kind of plywood?

Save your Money...... CDX, good 1 side is More than Plenty Good for what your doing.... I'd go with 1/2"... 5/8s" tops.... 3/4" is too heavy,+ is serious Overkill..... either paint it, or epoxy it, Then paint it.... you Need the paint to Stop the UV light.....
 
Joined
Jan 4, 2003
Messages
28
Re: Best kind of plywood?

Ut Oh!! I used PT on the transom, It is taking the glue very well. Hope it holds the 115 mercury! :rolleyes:
 

Chicken Ship

Cadet
Joined
Oct 30, 2002
Messages
8
Re: Best kind of plywood?

Well I'll be replacing my floor in my 17' Aluminum Sea Nymph. I am planning on using Marine grade sheets of 1/2". My question is what needs to be done to it before installing as a floor? I mean do I need to seal it or anything like that?
 

CTD

Petty Officer 1st Class
Joined
Nov 13, 2002
Messages
234
Re: Best kind of plywood?

I was under the impression that a good grade 1/2 inch AC plywood was a 5 ply and a marine grade was a 7 ply which would be stronger and flex less. 1/2 inch cdx is a three ply and flexes a lot.
 

mellowyellow

Vice Admiral
Joined
Jun 8, 2002
Messages
5,327
Re: Best kind of plywood?

has anyone tried to epoxy a few pieces of luan?<br />curious...<br />M.Y.
 

plywoody

Senior Chief Petty Officer
Joined
Aug 11, 2002
Messages
685
Re: Best kind of plywood?

Not all 1/2" CDX is 3 ply. The western 1/2" is typically either 4 or 5 ply. It depends on how long you want it to last. 1/2" CDX (or better yet, CCX will last pretty well if it is covered with say carpeting, and protected from sitting in water for extended periods of time. The better plywood you use, typically the longer it will last. Use a c grade innerply product, however (ie CCX as opposed to CDX) as the size of defects allowed are acceptable only in short term wetting applications, and will delaminate under any sort of extended periods of exposure to water. A c-grade inner ply is truly an "exterior" product, as opposed to a CDX which is an interior product which uses exterior glue.<br /><br />I would be very careful using Luan. There are a multitude of different species of wood that go under the generic name of Luan, and some have oils in them that will not adhere to fiberglass or epoxy. Some will, but without being a chemist, it is impossible to tell which is what.
 

PurpleDragon

Petty Officer 2nd Class
Joined
Nov 11, 2001
Messages
124
Re: Best kind of plywood?

Hey there BryanRedfish,<br /><br />I checked out their website, and contacted them to see about a supplier of their products for boatbuilding... Unfortunately no dealers in Texas. Do they have a dealer in your area? What part of La. .are you in?<br /><br />Thank,s<br />Rex
 

Hawkeye1

Petty Officer 2nd Class
Joined
Jan 15, 2002
Messages
142
Re: Best kind of plywood?

mellowyellow, I used 2 layers of ex luan from home depot for my floor. I was able to overlap the seams to make a realy solid floor with just 2 layers. I covered to whole thing with 1 layer of 17/08 biaxle. Epoxy stuck to this luan like stink on Sh!t. Pictures at this link below.<br /><br /> http://photos.yahoo.com/bc/formula2...os.yahoo.com/bc/formula2332000/lst?&.dir=/str inger-floor%2bproject%26.src=ph%26.view=t
 

Beeched

Petty Officer 2nd Class
Joined
Jun 22, 2002
Messages
110
Re: Best kind of plywood?

I checked out the Greenwood XL. Looks like a good product, however the following was in the first line of their specs. "Preservative: Chromated Copper Arsenate - Oxide formulation or equal."<br /><br />I don't think that I want the chemicals where they might seep and my dogs get exposed to them. At this point I am leaning towards 3/4" marine ply. Only because locally you cannot get 1/2" or 5/8". The price isn't bad at $59.00 for 4 X 8 sheet.
 

plywoody

Senior Chief Petty Officer
Joined
Aug 11, 2002
Messages
685
Re: Best kind of plywood?

You cannot possibly go wrong with the Marine grade. 3/4" CCX would probably run you into the mid to high $20 range per 4x8 sheet, and you are getting a lots better product with the marine grade.<br /><br />Good luck!<br /><br />John
 
Top