[dmdaws]

What would cause the weld material on the bow of my pontoon boat to disintegrate? Boat is docked in saltwater about 8 months of the year. Put it in in Oct. 2004 and just pulled it out. Water drained out of both pontoons. Weld material, that is left, is mushy and turns to powder when you touch it. I am told that it can't be repaired because the corrosion is too extensive.

[CATransplant]

Uffda! Not all aluminum alloys are corrosion resistant. Apparently the welding alloy used by your boat manufacturer isn't.It's even possible that the alloy has enough of another metal in it that you're getting electrolysis going on in the weld metal.Was this pontoon boat rated for saltwater use? I'd guess not, based on what happened.

[CATransplant]

Here's something from the Playbouy pontoon boat site:-------------------------Q. Can I use my Playbuoy or Tahoe pontoon boat in Saltwater? Top A. Your Pontoon can be used in saltwater with the following preparation and maintenance Preparation –If you plan to keep your boat in saltwater you must have all portions of the boat that will be submerged painted with an approved aluminum anti-fouling paint. This service is provided by your dealer or by someone recommended by your dealer. There is an extra charge for this service. In some cases you may need to have zinc anodes added to your boat to prevent electrolysis. Electrolysis is a deterioration of the metal caused by stray electrical current interacting with the saltwater. Ask you dealer whether he recommends zinc anodes. There is an extra charge for this service.

[dmdaws]

thanks for responding. I had a zinc on the boat. It is used up. Note that the other welds, that encircle the pontoons are affected. Did have the proper paint on the hull. This was the 6th year in the water in about the same location with no previous problems.

[CATransplant]

I'd suspect some stray electrical currents are playing a role here. Paint can only go so far in protecting aluminum from electrolysis corrosion. That your zinc was used up is an indication that something was going on.What to do? I don't know. Replacing the pontoons will probably be prohibitive in cost, given the age of your boat.I do note that a couple of manufacturers are offering pontoon boats with fiberglass or other plastic pontoons, especially for saltwater use. If you're thinking about replacing the boat, that might be your answer.I'm sure sorry this happened. It must be very frustrating for you!

[dmdaws]

thanks for your kind words. The cost of new pontoons is about the same as the value of the boat. I will sell the motor, anchors, lifejackets, trailer, etc. Funny thing is that I just signed the papers for putting the boat on consignment for sale with a boat shop.

[CATransplant]

Best of luck to you.

[bayman]

I wonder if the pontoons could be repaired using other methods besides welding....?

[malagaoth]

could the surface not be roughed up and fibre glassed? might not look pretty though

[bayman]

I would think it could be fiberglassed. If the fiberglass was left clear then the aluminum color would show through when polished. Otherwise, it could be painted whatever color you want. This might not be very cheap, but assuming the pontoons have foam in them it ought to be quite safe I would think - in terms of boating safety.

[Mike from Fenwick Island]

I feel for you. Just signed up on here to see if a similar question could be answered, and from the response it doesn't sound good for me. My anode dissapated this season, suggested reason is a short in the electrical system. (2000 Sweetwater). Being my first year as a boater, I ALSO used the absolute incorrect bottom paint on the pontoons - it contained 49% copper, and I have alluminum pontoons. Alas, pitting, along with severe pitting along the paint lines. So, not good remedy? I was thinking of scraping with a wire brush, and priming and painting with correct paint? Would I have to remove ALL of the old, improper paint?