Using Treated Lumber for Decks

[Zum]

Seeing as I(prob.we) didn't even realize there is a newer pressure lumber,never reallly looked to see what type did the damage to the boats.
There a few examples of pressure treated wood(prob. not the new stuff) affecting aluminum right here on the site...transoms,bottom of boats,pitting of a pretty new boat.
I see your on your thrid boat in 15 years maybe being "less" corrosive it hasn't taken effect yet,who knows.
It will take years(20+)before alot of people trust pressure treated in aluminum boat construction.
I mean why would you want to take the risk,maybe if the company would pay for any damage done by the new PT.
I think that would be a good experiment,aluminum,sandwiched between,or just against the new PT.
Leave one just to the weather,another soaked in fresh water(4hours)then brought out to sun dry(each day), could do the same with salt water.If it's a thrid party experiment alot of people would take notice,just not to many people will want to try it out on their boat.
Good luck with your crappie fishing.

 

[screwballl]

What I stated is opinions BASED ON facts and physics.

https://www.dossert.com/technicalinfo/corrosion.htm

Copper - potential volts -0.345
Aluminum - +1.30

...it can be seen that a high potential of 1.645 volts will be set up between these metals in the presence of an electrolyte (aka water, fog, humidity, water vapor, etc). If the two metals made contact with each other, in a period of time the aluminum would be corroded away in the reaction, since, of the two metals, it possesses the higher potential.

Where a connection comprising a junction of an aluminum and copper conductor is to be considered, several conditions must be observed in the selecting of the most appropriate connection. Aluminum because of its high Electro-potential with respect to that of copper will, in contact with copper and in the presence of an electrolyte, corrode progressively in the ensuing Electro-chemical reaction until contact between the two metals is destroyed (aka our Aluminum boat hull).

 

[linehand]

Wow screwball. LOL. I believe by looking at the quote you referenced someone is comparing conductors..simplified" the wire thingies that carry the stuff that turns on the lights". Probably should just stay away from the water in your floating conductor. Nothing to do with lumber or the chemicals used to treat the lumber. I think that the wood seller has a clue...that is all i'm saying. Personally I would just use aluminum and save the weight. Oh and one more thing about your quote reference; A over C. A good long lasting direct contact relationship can be had between copper and aluminum as long as the copper is below the aluminum in the connection. Unrelated to boating but thought i'd let you have one more thing to argue about.

 

[screwballl]

It is electrolysis that causes the corrosion, so it is not oxidizing "rust" like rusting steel. Like that page states, there are 2 types of corrosion: one from typical oxidation, which weakens steel but strengthens aluminum. The other from electrolysis such as the copper + aluminum situation.

When you have copper touching aluminum (including pressure treated wood and aluminum outdoors or on boats), it is fine by itself as long as there is no electrolyte between the 2 like water, humidity or other liquids. It is that passing of electrons from aluminum, through the water to the copper, and difference of voltage that causes the problems. So as long as your boat is in eternal dry storage and never sees humidity or rain or water, then yes you can use pressure treated wood that contains copper on aluminum boats... but a boat that never touches water is useless, it is like buying a new car and literally never driving it. That may be fine for a museum or showroom, but not real world applications.

So in laymans terms:

Copper from treated wood + aluminum on boats and/or boat trailers = BIG no-no!

Copper + aluminum indoors where there is little to no chance of water/electrolysis, it will be fine for decades.

 

[linehand]

Just from experience and since electricity has been distributed via overhead lines. In the harshest conditions to controlled. Aluminum over copper. Copper on top will eat aluminum in no time. There you just learned something. :lol:

 

[ohiolunker]

I'm having a hard time finding an answer to my framing questions and you guys seem to know your stuff. I'd like to use Simpson Strong Tie 2x2 brackets to fasten directly to my cross members to build a deck; however, I know theses framing brackets are galvanized. My question is is there anything I can coat/paint the brackets with to avoid galvanized on aluminum problems? Also, my entire boat will be Steelflexed so there will be minimal direct contact with the aluminum. Last question is if there is nothing I can do to avoid problems with the galvanized brackets, does anyone know where I can get them in stainless?