I pulled the tanks in the old green trawler. One was seeping the other seemed fine. They were 125 gallon in the laz, relitivly easy to get out. Plan was to use the old ones as templates. Turned out the only bad spots were on the bottom of the one. Had them sand blasted which left holes in the one that had been seeping. The bad was cut out out and replaced.
At the same time I had another inspection hatch cut and fitted to the top and added pick ups for fuel polishing. Tanks then got three coats of epoxy primer and three coats of white epoxy paint.
Total cost for sand blasting, repair and fabrication, pick ups and epoxy paint was just under $800.00. I did the removal, transport to the blaster and repair man. Paid the yard an additinal $100.00 or so to lift them back in.
Repair was well worth it in my case. The photos show before in place, after sandblasting, the holes, painted tank (both the same) and cleanouts.
At the time my wife worked for Loctite and their development lab in Rocky Hill Connecticut was very helpful with sealants. The guys there told me they offer help to anyone who calls. We are both retired now so no more connection.
North Pacific 45