Why so all this speculation? Talk to someone who makes tanks, then
follow their advise.

I had aluminum diesel tanks made at Pipe Works, in Long Beach, Ca. They
know what they are doing.
Jim

Wayne.B wrote:

If everything goes according to plan, I'm about to buy a Grand Banks
49 trawler that needs new fuel tanks (500 gallons each).

Any thoughts from this group on the best material for new tanks,
fabrication hints, and/or removal/installation suggestions?