Fuel tank

Are these outboard tanks, under the decks? Is that why they'd be expensive? No, I would not epoxy it. Bladder is an option, but not one that I'd like, either. IF you can get to the tank and remove it as a whole unit, you can replace it without a big expense.

No shortcuts with gasoline. Wouldn't trust epoxy long term especially considering how much corrosion may be inside the tank, and a corroded tank could wear against a bladder causing a leak. Result BOOM. You can get tanks made in whatever configuration that works. You could even put in 2 smaller tanks if you need to fit. Get new.

Replace the tank or sell the boat at a discount with full disclosure. The options you mentioned are playing with fire. Literally.

Replace the tank with 2 150 gallon tanks, easier to get in. DON'T patch a gas tank OR put a bladder inside of a bad one.

Boom....... Do it right. If there's one rupture, there will be more. No patching. Bladder will chafe through. Use your brain.

All excellent advice. Tough to accept, but search YouTube for “boat explosion” to understand why.

Epoxy will not work for long. Bladders usually don’t work on marine tanks because tanks have baffles.

no shortcuts on fuel tanks especially gas boats.

Our boat, floating office and home was on the Huckins dock for many years.
Those kids had Carver tank replacements down to a army drill.
Where I would need to pull exhaust manifolds or remove the whole engine, these kids did save that on most models and removed the wood, panels, trim and options from above the tank and replaced with new. Well, they are great carpenters and finishers.
BTW, Don't feel pregnant. Carver gas tanks suck.
If one side is leaking now, it's a bad poker hand your holding till the other tank leaks.

REMOVE the big tank and replace it with 2 equal sized small tanks that equal the size of the tank you removed.

Do it the right way. What’s the point to half ass it now if you still have to pay later? The odds are you won’t be able to sell it someday unless you correctly replace the tank or credit the buyer to get it done. But even with a credit I doubt anyone would want to take on the problem. So what are you gaining? Why not have it 100% correct for yourself since you’re going to have to make it correct for the next guy anyway?

Yep...

There is a company in new jersey that specializes in rebuilding fuel tanks from the inside. They do travel around the Chesapeake as well. They access the tank from the ends or top and cut it open the weld a new bottom into the tank. I have used them on several boats with good results. My experience has been $14,000. on a 400 or so ga tank. Probably businesses like this elsewhere.

Right! SP Tanks

SP yea. They did a nice job for us on several occasions where tank access was near zero.

$14,000 sounds like a lot to invest in a fuel tank for a 25 y.o. gas boat worth at max $69,000 per Boat Trader and more likely less than $55,000. 37' is right at the cusp where it's hard to sell a gas boat in good condition. It brings to mind a warning I give about the troubles with being a boat's last owner. After investing that $14,000 how long before one or both of those gas engines need a rebuild, and you've basically doubled your investment in a boat worth less than half what you have into it. May be time to cut losses.

Insurance may help with the repair. Not likely but worth the call.
If you use and enjoy the boat 14K is well spent. If you are done with it that is another story

Were they diesel fuel tanks or gas ?

All of our repairs were bilge mounted diesel tanks. The tech did say they do gas as well just with a few cautionary steps.