problem with pressure treated bunks

[vettman]

Hi all, Haven't been on in awhile but have some interesting info. Looked but don't know if this subject has been posted previous. My neighbor just bought a 2007 G3 22' pontoon. Boat sat mostly on trailer by previous owner until it was used to go out on. My neighbor brought it home and put it in the water tide it to his dock and within 2 days it started taking on water. Seems that the pressure treated bunks, which as of 5 years or so ago are treated with COPPER , ate thru the the aluminum logs. There is a chemical reaction between the copper and aluminum toons , wet bunks being the catalyst. The logs have small pit holes thru them wherever they sat on the bunks. Apparently the previos owner was not aware because they would take boat out of water after every use. I ,being an siding contracter have had this problem with capping p.t. with aluminum coil .It will eat it up in no time, as if acid was pored on it. To do it to .080 thick aluminum is amazing. Most of the new p.t. have stickers that warn against use with aluminum. Thanks and beware

 

[rrhodes]

Re: problem with pressure treated bunks

Yup and salt does not help either.

 

[Jeep Man]

Re: problem with pressure treated bunks

Yeah, PT and aluminum combination is a definite no-no. Your neighbor will need to visit a good aluminum welder.

 

[5150abf]

Re: problem with pressure treated bunks

Depending on how many holes there are it may not be weldable, filling 300 pin holes is not going to be pretty or easy, you have to clean out each hole before welding or you will just make a bigger leak, could be in for a new set of tubes.

Was there carpet on the bunks or it was sitting on the bare wood?

 

[Silver Eagle]

Re: problem with pressure treated bunks

I just reboarded my bunks with Pressure treated wood. but First i painted the wood with a good porch and floor exterior paint.

 

[jeeperman]

Re: problem with pressure treated bunks

Could you not wire weld "nuskin" over the bunk area with the same aluminum as the tunes in the effected area?

And always use "marine use" pressure treated wood around aluminum.
"Marine use" uses the old formula.

 

[vettman]

Re: problem with pressure treated bunks

The bunks had carpet on them. Probably made problem worse because they stayed wet longer while on the trailer. Haven't heard of Marine only 2x4's.I think vinyl strips layed on the 2x4's and then carpeted would solve any problems . Not too sure about paint though. If it was always dry paint might work. Not sure what you mean jeep. Would that not cause a scrapping effect when loading and unloading ?

 

[bigdee]

Re: problem with pressure treated bunks

I just reboarded my bunks with Pressure treated wood. but First i painted the wood with a good porch and floor exterior paint.

Actually,aside from the corrosion issue, there is little benefit to using PT bunks. Regular southern pine 2x4 will last about as long as the carpet anyway so I just replace both every 4 or 5 years.

 

[lncoop]

Re: problem with pressure treated bunks

Actually,aside from the corrosion issue, there is little benefit to using PT bunks. Regular southern pine 2x4 will last about as long as the carpet anyway so I just replace both every 4 or 5 years.

Roger that. Also, not doubting the OP's assertion that the PT bunks were a factor. However, I can't help but wonder whether the salt was really the culprit.

 

[jeeperman]

Re: problem with pressure treated bunks

The bunks had carpet on them. Probably made problem worse because they stayed wet longer while on the trailer. Haven't heard of Marine only 2x4's.I think vinyl strips layed on the 2x4's and then carpeted would solve any problems . Not too sure about paint though. If it was always dry paint might work. Not sure what you mean jeep. Would that not cause a scrapping effect when loading and unloading ?

After some research, the PT makers advise against allowing aluminum to contact any variety of PT lumber.
But they do mention using custom made vinyl trim to cover the bunks as a barrier. Then use carpet over that on bunks.
I guess vinyl siding guys can bend up channels that can be used on 2x4's and 2x6's.

 

[jeeperman]

Re: problem with pressure treated bunks

Roger that. Also, not doubting the OP's assertion that the PT bunks were a factor. However, I can't help but wonder whether the salt was really the culprit.

There are quite a few conventional pontoon boats sitting on lifts for years in salt water enviroments.

 

[lncoop]

Re: problem with pressure treated bunks

There are quite a few conventional pontoon boats sitting on lifts for years in salt water enviroments.

No question. However, it stands to reason those boats see frequent use followed by washdowns. Boat sat mostly on trailer by previous owner until it was used to go out on. This statement infers that wasn't the case with this particular barge. I concede that I'm reading between the lines, but it seems reasonable to assume there are many barges sitting on carpeted PT bunks as well, in which case one would expect to hear of the same issues from fresh water boaters. Again, I'm relying largely on assumptions, but they seem like reasonable assumptions to me. And, before the flaming begins, EVERYONE PLEASE UNDERSTAND I AM NOT SUGGESTING PT LUMBER WON'T HURT ALUMINUM. We all know that is not the case. I'm just hesitant to place sole blame on the PT bunks. Could be wrong. Happened once before.

 

[jeeperman]

Re: problem with pressure treated bunks

Down here it is rare to see freshwater piped out to the end of the dock to the boat lift.
And if it was, I think maybe the portion of toob resting on the bunks would never get rinsed off.
Making it the same as a trailer boat that gets washed.
I am sure the salt does add something to the equation.

 

[lncoop]

Re: problem with pressure treated bunks

So you're saying down there most toons on lifts don't get rinsed? Interesting. As you can see from my location, salt is not a concern. Like I said; assumptions.:redface:

 

[a1nowell]

Re: problem with pressure treated bunks

OK,
Ya'll got me concerned. I put new PT bunks on my trailer last year. They are covered with carpet but I have seen spots on the carpet where something is leaching thru.

Do you think covering the top of the bunk with something bunk slips will insulate my toons? Something like this:
http://www.wholesalemarine.com/p/T-D-86164/Boat+Trailer+Bunk+Slick+Kit,+10+piece.html

 

[bigdee]

Re: problem with pressure treated bunks

OK,
Ya'll got me concerned. I put new PT bunks on my trailer last year. They are covered with carpet but I have seen spots on the carpet where something is leaching thru.

Do you think covering the top of the bunk with something bunk slips will insulate my toons? Something like this:
http://www.wholesalemarine.com/p/T-D-86164/Boat+Trailer+Bunk+Slick+Kit,+10+piece.html

You could replace your bunk boards for less money. The hardware used to fasten the PT will fail anyway unless it is approved to be used with PT. You can probably salvage your carpet and reuse it. This new PT is NOT as rot resistant as the old arsenic PT.

 

[Jeep Man]

Re: problem with pressure treated bunks

OK,
Ya'll got me concerned. I put new PT bunks on my trailer last year. They are covered with carpet but I have seen spots on the carpet where something is leaching thru.

Do you think covering the top of the bunk with something bunk slips will insulate my toons? Something like this:
http://www.wholesalemarine.com/p/T-D-86164/Boat+Trailer+Bunk+Slick+Kit,+10+piece.html

As long as you have a COMPLETE barrier between the PT you'll be OK. The carpet will retain the chemicals. My suggestions would be to replace the PT or remove the carpet and use a vinyl or rubber barrier.

 

[Silver Eagle]

Re: problem with pressure treated bunks

I'm in no hurry this year to put the boat in the water. I can't stand unloading or loading a boat in cold water. So in a couple of weeks I'll start launching the boat back into the northern end of the Chesapecke Bay. Brackish water most of the time. I ordered the plasic sleeves that seperate the toons from the carpeting. .So each time I put the trailer in the water I'll put on a sleeve or two until the job is done. I'll do this in the middle of the week when all you guy's are at work. Being that I'm retired.

 

[a1nowell]

Re: problem with pressure treated bunks

Silver Eagle,
What kind of sleeve?

Is it something like this?
http://tiedown.com/abunks.html

 

[ChampionShip]

Re: problem with pressure treated bunks

Would epoxy coated regular non-treated wood with carpet be the solution to all of these issues? Seriously wondering, wouldn't rot and doesn't have copper.