treated plywood corrosive to aluminum?

[hawk232]

im about to replace the transom on my aluminum boat and was just curious if i would be safe to use treated plywood for it. i know that the new treating process create a condition that is corrosive to galvanized products, and i was just curious if any reaction would occur with aluminum.

Thanks,
David

 

[Bob_VT]

Re: treated plywood corrosive to aluminum?

Go with a marine plywood ...... I would not use pressure treated due to the chemicals and how they might prevent glues, epoxies and paint from adhering.

 

[stevieray]

Re: treated plywood corrosive to aluminum?

Treated lumber should DEFINITELY NOT come in contact with bare aluminum. The chemical salt used to treat the wood will dissolve the aluminum in short order - even shorter if it gets wet.

 

[Bondo]

Re: treated plywood corrosive to aluminum?

Treated lumber should DEFINITELY NOT come in contact with bare aluminum. The chemical salt used to treat the wood will dissolve the aluminum in short order - even shorter if it gets wet.

I've been hearing this Over,+ Over,..............

Yet, My personal Experiment says it's just Not True......

I put a P/T transom into my Starcraft Islander over 6 Years ago,+ can find absolutely NO ill effects.............

I Glued it together with Resorsinal,+ Soaked it with Boiled Linseed Oil,......
Then slid it into place,+ bolted it up.........

No Problems,+ No Degradation of the Wood, or the Aluminum.................

Btw,..... With this old Leaky tinboat,....
The bottom 6" or so of the Transom Wood is Always Wet.............

 

[stevieray]

Re: treated plywood corrosive to aluminum?

Treated lumber should DEFINITELY NOT come in contact with bare aluminum. The chemical salt used to treat the wood will dissolve the aluminum in short order - even shorter if it gets wet.

I've been hearing this Over,+ Over,..............

Yet, My personal Experiment says it's just Not True......

I put a P/T transom into my Starcraft Islander over 6 Years ago,+ can find absolutely NO ill effects.............

I Glued it together with Resorsinal,+ Soaked it with Boiled Linseed Oil,......
Then slid it into place,+ bolted it up.........

No Problems,+ No Degradation of the Wood, or the Aluminum.................

Btw,..... With this old Leaky tinboat,....
The bottom 6" or so of the Transom Wood is Always Wet.............

Bond-o,
Maybe they're using different treatment chemicals now or maybe that linseed oil soaking "sealed in" the bad stuff enough to not affect your boat.

At my old waterfront, I had a pretty heavy aluminum angle bracket that I used to rig up my ice-eater bolted to a piece of treated 2x10 & it had turned to powder within a year.

Strange stuff.

 

[clemsonfor]

Re: treated plywood corrosive to aluminum?

Marine Pkywood is pressure treated. As a forester i can say that the plant that i have seen that makes it puts it in thier chamber and pulls a vaccume on it like thier poles as then floods the chamber with preservative.

-nate

 

[Bondo]

Re: treated plywood corrosive to aluminum?

You're probably Right Steve,.......
But,....
I can only Judge by My personal Experinces........

I Refitted that hull in 1999,........
I've "heard" there has been changes in the formula used,+ but Don't Know when that might of Happened......

All I know is, what's stated above,+ the Fact that My Epoxy on the Floor, which is built with the Same P/T Plywood is holding Up as Designed........
No Delaminations or Degradations of Any Sort.......

 

[Frank Acampora]

Re: treated plywood corrosive to aluminum?

Pressure treated lumber usually has Chromate and arsenate salts. That's why you are supposed to use safety equipment when building with it and wash well after handling it.
Figure out where they lie on the table and figure out if they will set up a galvanic reaction with aluminum. That'll tell you whether to use it or not.
I suppose if you seal the salts in after drying it, it might be ok to use in a marine environment.

 

[pike hunter]

Re: treated plywood corrosive to aluminum?

Never use ACQ treated wood (alkaline copper quaternary) on aluminium because it's very coorsive for alum. ACQ replace CCA treated wood in 2003. The only one that you can found now is the real and expensive marine plywood that is still treated CCA.

 

[Rick K]

Re: treated plywood corrosive to aluminum?

Why not use ACX, bonded together and sealed with a 2 part epoxy? The ACX is half the price, almost as strong, and in my case, worked perfectly. ACX is available at Lowes for about $30/sheet.

Rick

 

[drewmitch44]

Re: treated plywood corrosive to aluminum?

i used pressure treated plywood to make my front and rear casting decks on my 14' simi-V utility boat 2 years ago with no problems. I used bare 1.5" aluminum angle for supports for the floor and rivited that to the ribbs of the boat and screwed the treated ply right on to the aluminum angle and also into the front and rear tank seat of my boat. The front and rear seats are aluminum just like the rest of the boat. So far so good! Also i made storage hatches in the casting decks so i can see inside the floor and there is no corrosion in there. This will be the third year coming up that i have used it like that. I didnt glass or treat in any way the plywood just carpeted the top where i walk around. Maybee im just lucky but i dont think that treated ply is that corrosive to aluminum.

 

[steelespike]

Re: treated plywood corrosive to aluminum?

The whole problem with any untreated plywood is if you get any leak through the sealer/fiberglass you will get rot and it will go fast because it never dries out and it cooks under the sun.
The trick to get PT to take fiberglass or paint is to be sure it is dryed out.Most PT is wet and needs to dry for some time depending on the drying conditions.
Boat aluminum is anodized so is resistant to corrosion.
Regular aluminum wouldn't last hardly any time in salt water and would get pretty ugly in fresh water as well.
PT wood is not suposed to leach.
Dry it good,seal it with a couple of coats quality paint or sealer maybe a coat of paint or pick up bed coating
on the aluminum where it contacts and it will out live you and your infant first born.My PT transom is over 22 years old comepletely unpainted April to December in the water ,still going strong.My dock is about the same age unpainted or sealed until a couple of years ago.

 

[tmh]

Re: treated plywood corrosive to aluminum?

I'm using PT plywood for my stringer repair and floor for just the reasons mentioned above - i don't want to spend half a day carefully sealing every hole I screw in or whatever else could let moisture in. It's a 20 yr. old boat, NOT a work of art! If PT gets me another 10 yrs. that's fine. It's so much easier knowing I don't have to worry about every drop of moisture intrusion!

Whatever they did making it new didn't work so well....that's why I'm replacing the floor! THAT was marine plywood with lots of glass/resin.

I do know that PT needs time to dry out. I bought my wood last fall to be used in spring on the boat. I'm not the least bit worried about it with months to dry. Like the other guy said, my deck holds up fine with little or no care. Structurally, PT stays sound for decades.

 

[iwombat]

Re: treated plywood corrosive to aluminum?

Boat aluminum is usually not anodized, nor are the rivets or other fasteners. What keeps it from corroding in water is the thin outer layer of aluminum oxide that acts as a protective barrier, (or the paint or in rare cases the anodized coating). The chemicals in PT wood react with the aluminum oxide removing the protective barrier. Plain old Al reacts with all kinds of stuff.

PT wood creates a classic two-part reaction in the presence of water.

 

[hawk232]

Re: treated plywood corrosive to aluminum?

wow lots of debate, thanks for all the info!!

 

[iwombat]

Re: treated plywood corrosive to aluminum?

I guess the gist of it all is that unless you're certain of the chemicals in the PT lumber (good luck). And, you know they don't react with aluminum oxide. Then, it's probably safe to use PT lumber. Otherwise, I'd be playing it safe if it was my boat.


(For that matter, I did play it safe with my boat)

 

[tmh]

Re: treated plywood corrosive to aluminum?

Yeah, i agree i guess. I'm not dealing with aluminum in my case (may takeanother look to make sure) because fiberglass boat and wood stringers.

 

[hawk232]

Re: treated plywood corrosive to aluminum?

yea, i guess ill just play it safe and get some marine grade, thanks for all the info!!