this might sound ridiculous

[orbitz]

just wondering whether anyone has used pressure treated plywood when re-building a the deck on a boat?

 

[Bob_VT]

Re: this might sound ridiculous

Well as long as the boat is not aluminum.since PT and aluminum are a big NO. Are you wanting to use PT to stop bugs??

PT is usually too wet and must be dried before you use it to seal it up.

Exterior grade or marine ply are better choices.

 

[aparis]

Re: this might sound ridiculous

I read quite a few threads on this topic. I too was not entirely convinced... If everyone warns us about using PTW, I haven't read from anyone who might have actually used PTW.

I decided, myself, to stay away from it. You might have read that pressure-treated lumber now relies on a substance called alkaline copper quat (ACQ) to prevent from rotting. And Aluminum is especially vulnerable to corrosion when in contact with copper.

I read somewhere that in the states you can still buy CCA (Chromated Copper Arsenate) pressure treated wood for marine applications, that is safer for using on an aluminium boat. I don't know about Canada.

Having said that, there is a piece of PTW still attached on the hull I bought, to reinforce the transom.

And there is no sign of corrosion... It might be because the paint, on the aluminium, acts as a barrier. I don't know what type of PTW it is, or how long it has been there for.

 

[BigBoatinOkie]

Re: this might sound ridiculous

Agreed. I always recommend fiberglassing the deck, and I've heard many times that PT can cause problems with adhesion and penetration of the resin. I haven't seen it first hand, but it makes sense to me.

 

[109jb]

Re: this might sound ridiculous

I did it backward. I put PT in an aluminum boat and exterior grade in a fiberglass boat.

On the Aluminum boat I usedrubber tape between the aluminum stringers and the wood to separate them and prevent the chemicals in the wood from corroding the aluminum.

On the fiberglass boat I didn't want to wait a month for the wood to dry so I used exterior. If I had it to do over on this boat I would have used the PT and I would have only tabbed the stringers and deck and not covered the whole deck with glass. Then I would have coated the deck with truck bedliner and called it done.

 

[aparis]

Re: this might sound ridiculous

Interesting, 109JB... So far you did not notice any corrosion?

I would have been concerned that the chemicals might wash away and end up corroding the hull in an aluminium craft. Like in the bilge area. This is what was happening with the previous generation of PTW and caused their ban: arsenic was washed away and contaminating sand in playgrounds.

 

[109jb]

Re: this might sound ridiculous

Well actually I can't say for sure if what I used was CCA which shouldn't cause corrosion, or ACQ which does cause corrosion. I did it about the time they switched. Back then I didn't know which was the one that caused corrosion but I knew one of them did. I The rubber tape was to play it safe. In any case I had that boat until last year so it lasted at least 7 years that way.

 

[ondarvr]

Re: this might sound ridiculous

PT plywood is used in new construction on many brands of boats, its considered an up grade, this product is kiln dried though.