Pontoons pitting under trailer bunks

PondTunes

Petty Officer 1st Class
Joined
Jun 7, 2007
Messages
387
Picked up a 2002 model parti kraft toon recently with a 90 hp Honda 4 stroke, the boat had been sitting on the trailer for about 4 years so it took some work to get i it running again. The motor has been tuned up and running quite well but we left it in the water at a friends dock last weekend. The next day the boat was sitting way low in the water. Ended up borrowing one of the narrow river trailers and pulling it out.

When we pulled it out we found several spots that were leaking all from deep pitting in the aluminum toons. The only place there is any damage is where the boat sits on the trailer bunks.. we were able to clean and weld up the pitted places, and the meta welded quite well.

I don't have any information about the boats previous owners but did find a spot on the bottom of one of the toons where someone had looked at having it fixed (there were measurements for patch pieces written on the bottom of the toon in sharpie).

Anyways what would cause pitting on the aluminum while the boat is on the bunks? We do not run in saltwater, but again I have no history of the boat.
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
No expert here, but picking up bits and pieces from being on this forum I have read about pressure treated pine not playing well with aluminum. Do the bunks look newer, like they have been replaced? Just tossing that out there. Glad you caught it in time and did not have to leave it on the bottom somewhere!
 

ahicks

Captain
Joined
Sep 16, 2013
Messages
3,957
Years ago this was never an issue, but now the new pressure treating (green) is corrosive to aluminum. Lot of guys are finding out the hard way. Inexpensive plywood, when used for re-decking, has the same issue.
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
Agree about the PT. Check the bunks and decking to see if pressure treated wood was used.

PT eats aluminum for breakfast. Lunch and dinner, too.
 

PondTunes

Petty Officer 1st Class
Joined
Jun 7, 2007
Messages
387
That seems to be the conclusion I've come to as well, think I'll source some of the pvc bunks or just replace them with non treated bunks
 
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