Replacing Trailer bunk on Aluminum Boat, treated lumbar?

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Dont use carpet

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Care to elaborate on this?

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I’ve heard that the copper can leak out of treated 2x4s causing aluminum damage.

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100% accurate.

I'm not sure why no carpet if you don't use the treated lumber.

So either go untreated with bunk carpet (don't go cheap on the carpet, use the stuff designed for bunks and stainless hardware); or use treated lumber and some sort of impervious barrier, like PVC, etc...

Anybody have composite bunk boards? Seems like a natural solution

Ultimate Bunk Boards

Have seen them before just haven't experienced an issue with my boat having fished mainly saltwater. Tough to justify the $$$ to get those for me currently. However it does look like a pretty good option.

I know someone who had an Xpress that was only two years old, full of pin holes from the treated bunk boards eating through. I had never heard of that before, but supposedly it's the newer pressure treated lumber, not the older stuff. In fact, I have an old beater flatboat with bare treated boards and bare aluminum bottom and no problems. But I also have an '06 G3 that originally had untreated boards that rotted out a few years ago. I replaced them with treated boards and re-used the original carpet. So after finding out about this issue, I jacked my boat off the trailer, and sure enough, I had corrosion just starting in a couple of places. From what I can tell, it will only affect bare aluminum. I have scratches to bare aluminum in other places with no corrosion, and where the paint is still in tact under the boards (most all of it), there's no issue. So the problem is just with treated boards (in the last ten years?), on bare aluminum. Carpet doesn't provide a sufficient barrier from the chemicals in the wood. Since my G3 is dark red, and I already knew of Glyptal being a really durable coating (red electrical winding coating), I painted the bottom of the boat the entire length of each bunk board with it. I also had a quart of black flex seal I rolled on the black carpeted boards. I don't think the flex seal is doing anything. But the Glyptal shows no sign of deterioration.

I've also heard of people's aluminum window frame wrapping on their homes being eaten out by the treated wood too. Again, my house is almost 20 years old, and I have no issue. So it goes back to the newer treated wood.

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First pic is a small spot of corrosion where it sits on that board. The size and degree point to how recent it began-when I put new boards a couple years earlier. I'm sure it wasn't there with the non-treated original boards. I had other spots of the same maturity. Note there's no issue where the paint is in tact.

The second pic is of scratches where there are no boards - no corrosion. If it was the quality of the aluminum, there would be corrosion there too after 12 years of exposure. Take it from someone with direct experience- protect your boat from the treated wood currently being sold. Mine came from Lowes. It's far too widespread to be coincidence and anything but the chemicals in that wood. They also sell caps that go over boards, that came out just for this reason. Anyone who says differently is misinformed or ignorant.

Just for the record, anytime I take it in saltwater, without exception, I stop and launch it in freshwater on the way home so everything that was put in saltwater, is thoroughly rinsed/flushed.

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Mine came from Lowes.

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Lowes lumber is treated with copper azole which is not rated for contact with aluminum. Home depot lumber generally uses micronized copper azole which is rated for contact with aluminum. I don't think it is recommended for contact with constant moisture, though.

LINK

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Wood pressure-treated with Micronized Copper Azole has corrosion rates on metal products similar to untreated wood. Use fasteners and hardware that are in compliance with the manufacturer’s recommendations and the building codes for their intended use. Aluminum building products may be placed in direct contact with wood pressure-treated with Micronized Copper Azole used for interior applications and above ground exterior applications.

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My transom is built out of home depot treated wood out of my own ignorance. I had no idea about the aluminum corrosion thing since it is my first boat. I bought the boat for 100 bucks so I didn't bother changing it, if it lasts a couple of years i'm fine with it. My bunk boards are treated with micronized copper azole with PVC on top. I'm actually replacing them with untreated and carpet this weekend since the PVC is damaging the rivets.

Recent thread

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Anybody have composite bunk boards? Seems like a natural solution Ultimate Bunk Boards

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When I had a boat, I used these for about 3 years. They are really great for shallow landings, because they are slick. I wouldn't unsecure the boat until it was partially in the water and they are too slick to walk on. If I still had a boat, this is what I would use.