check you mail

ADD MORE WATER, SINK IT AND PUT THE INSURANCE $$ TOWARDS GO FASTER MOTOR PARTS FOR YOUR REAL BOAT!!!!!!!!!!!!

Actually any good shop with a mig set up for alum. can do what you need done. I have seen alot of guys weld in a small ID threaded fitting to be able to actually add a slight pressure to the sealed section of the tube. Also makes it easier to pressure test for the dreaded leak. For the foam the tighter the cell the less chance for water intake, but if sealed and pressure checked any type would work. What about the 2 part foam poured into alot of smaller boats under the floor for flotation. This stuff is made for the marine environment and expands to the size of its container. Try Jamestown distributers ( they are a supplier of materials to the boat mfg industry) I buy stuff from them all the time. 1-800-423-0030
www.jamestowndistributors.com
I still think you should sink it but good luck.

FOUND THE PART # TO ASK FOR FOR THE FOAM
FIB-5611 small size FIB-5614 LARGE SIZE ask them to calculate for the size void your filling. GOOD STUFF

I live off the St. Johns in Eustis FL and alot of people here are filling their tanks with expanding insulation foam. Seems to keep them on the water, can't say I endorse the practice, but check into that. But how did water get into the tanks? Seems a bit odd to me.

There are several different types of foam, but for boats to have Coast Guard approval the foam must be at least 95% closed cell. I believe the pour in Polyurathanes are 95% to 98% closed cell and the spray in's are 99% closed cell. Closed cell foams cannot become waterlogged where open cell foams, like styrofoam, can become waterlogged. If you do a search on closed cell foams you can find the best for your application. I am very surprised you would have open cell foam in your tubes.

He's had 4 and a half years to work on it.
Maybe we can get an update.

Pontoons have gotten popular since 2002.