I understand that foam holds water and can create all kinds of issues,
Not if you install it the way I've been telling folks on here.
Yea...You still lag bolt it in....Thats to keep it in place when foaming it in. How many lag points will he use?
So....I'm going to start from the beginning once again for your benefit.
New tank material is upgraded from 1/8 to 3/16 5052 alum.
A vent is added at the back and T's into where the location of the front vent is.
A billet flange 1/2in thick is made [Drilled & taped] for the sending unit.
After tank is built....alum is cleaned of grease & oil...[wax & grease remover]
Then tank is sanded with a DA sander with 80gt.....and cleaned again with wax & grease remover.
It then gets 2 coats of Coal Tar epoxy rolled on it.
It then gets set into the boats coffin and lag bolted.
Using 4lb density 2 part foam it is poured to even with or slightly above the top edge of the tank.
The foam is cut flush with the top of the tank.
Using 6in wide 12oz fiberglass.....Half on the tank and half up the edge of the coffin. That fiberglass is laminated in.
A limber hole is installed even with the top of the tank....thru the aft coffin bulkhead which would allow ANY water that go past the pie plate gasket to exit that area.
You have now installed a tank that will outlast You.
The trick with foaming a tank is Never allow water to get to the alum....You have done this 2 fold following my method....Coal Tar epoxy seals the alum......Fiberglass the top edge around the tank keeps water out of the foam.
Also document [pix's] the install in every phase, as it's proof when resale time comes and Will increase the boats value.
90gal X 6.5lbs = is round figure 600lbs 600lbs being Slammed around.....Yes....Thats what a boat does.....and 4- 1/4in Lag bolts....I would not trust.