I have a 10 yr old fiberglass pool which has lost most of its gelcoat and has many thin places. You can see fiberglass fibers in some places as big as 16" square in the bottom especially. It has no cracks and does hold water.
We're considering having applied a rolled on coat of gel coat. My understanding is that gelcoat is just polyester resin with pigments or solids added, and possibly some other additions. The plan is to sand the entire pool and wipe down with acetone.
In a thread from a few years back, a poster by the name of 'glassguy1' said....'Polyester resin was never meant for underwater use and will always fail on a swimming pool. Gel coat will not laminate to polyester resin if it's underwater for even a short amount of time'.
Those comments were a little confusing. I'm pretty sure glassguy was recommending re-gelcoating a fiberglass pool to extend its life. But then he mentioned that polyester resin was not meant for underwater use, and that polyester resin would not bond to gelcoat.
I've seen pool manufactures send their own tech reps out when there was spider cracking all over a new pool surface. Those techs sanded the entire pool and the sprayed on one coat of straight gel coat. Some 8 years later it's looking great. (not my pool)
If any forum guys or gals have done a re-coat with gelcoat, I'd appreciate their kindly let me know if the plan I've outlined makes sense. Likewise if you have the experience and can compare or contrast the effectiveness or projected life of new gelcoat vs. epoxy paint that would be of high interest too.