Getting the ole' CC Wellcraft ready for this year. My SIL took the boat to a near by Marine Dealership/Shop, had a new Merc. Tach put in and the hourly checkup, fuel system gone thru, new plugs,gear lube etc. He told the guys there that it ran kind of sluggish up at the lake and do what ya gotta do to get it right. After a brief discussion about what the shop did, he told me something they did they I personally never heard of. My Poly/plastic fuel tank is below deck...50 gallon. They did something to clean it out.....then he told me they sprayed the entire inside of the tank with something which put a coating on the inside walls. What was this stuff? Have you heard of this? Anyway, "Nelly Bell" is ready for another year.

Found this.

https://www.kbs-coatings.com/tank-sealer-directions.html

Used it on a motorcycle tank a few years ago. Still working.

SE Kansas grass grower

I'd be curious to learn what could have been sprayed in there that would adhere to a polyethylene fuel tank.
The KBS coatings stuff would work on metal, but not poly. All kinds of stuff can be used to clean gas residue gunk out of a poly tank but never heard of coating the inside of one with anything.

Most of the shops out there are honest, but I would have to question spraying the inside of a plastic tank. There's nothing to corrode. You drain the old gas, flush the tank, fill it and go.

Sounds like BS & a fleece job to me. How MUCH did this cost & what is the PURPOSE of it. And WHY is it needed? Has NO benefit???? I wouldnt want ANYTHING but FUEL in MY fuel tank.