Fiberglass repair and resin advice for inside out boat

[kendrickg]

Hello all, I have a few questions about fiberglass repair on a small pool shell...I know this is a boat forum but you guys are much more knowledgeable about fiberglass than the pool forum people!

The pool shell is basically an inside out boat, with the shiny fiberglass side holding the water. We acquired this shell at a good deal as it was partially installed by an amateur then removed and sat outside for a few years where it picked up a ding from a tree branch. There are also issues with the gel coat cracking, mainly on the bottom and steps. My novice opinion of the cracking is that some are stress related from being handled and some are because it was too thick. It is obvious that I need to fix the hole and I have watched countless videos on the hole repair, but what is not obvious is how big of a can of worms do I open with the gelcoat cracks. The ones from the floor to the steps transition definitely need to be repaired, but I am not sure how to deal with the rest of them. I have seen videos of people covering the entire pool in CSM and then redoing the entire gelcoat, but that is on pools that are 20 yrs old and faded, this pool has never been used so the gelcoat is beautiful on most of the walls. Maybe I could just CSM and relcoat just the bottom and steps?

I have read the basics that gelcoat is foolproof on top of poly resin, but epoxy resin adheres better for repairs and is better for under the water. I have also read that gelcoat CAN be used ontop of epoxy in ideal conditions. But being I am a novice.....what would be my best plan of attack?

My questions are basically as follows:
-Being all the repairs are "below the water line", shouldn't I use epoxy resin for repairs?
-But if I choose epoxy, can I still use gelcoat?
-If I cant use gelcoat on the epoxy resin I would have to paint, but I have read a lot of bad reviews of epoxy painted pools.
- If using gelcoat is the best coating for being submerged, should i use poly resin then for the repairs?
- Can I just let the few hairline cracks in the walls go and not touch them?
- Being that the finish surface is always underwater and not very visible the finish does not need to be glass smooth and perfect like a boat so would I even need to sand the gelcoat? Actually any orange peel effect could be beneficial for grip.

I have never done any fiberglass work, but I have been watching a lot of videos and trying to read as much as I can on the basics. I would like to figure out which resin to purchase so I can start practicing the techniques on sample pieces before hacking into the pool shell. I do have a good amount of experience with industrial epoxy and polyurethane paints so at least it's not my first time mixing two parts together, lol. Thanks for reading and any advice is welcomed!

[ttex]

I've been working on swimming pools my entire life and my dad built fiberglass swimming pools for over 20 years until he retired.

I just want to explain that a fiberglass pool shell that is not installed in the ground and has holes and cracks in it is like a sailboat hull completely bare laying over on its side on the hard with cracks in it.

Would you buy that hull and expect to turn it into a sailboat?

That's all I have to say here.

[Cheechako]

Regular laminating resin and cloth have been used for decades for boat hull repairs. It is said that epoxy is better, but frankly, the normal resin works fine. I've not seen fiberglass pools get blisters but I suppose maybe some do. I see no point in have a few spots in a large pool epoxy.
Gel coat is super brittle and with that pool being moved around etc that's why you have some cracks I imagine.
It's a pool not a boat. There is no life risk problem with how you repair it.

I'd grind out the worst crack and see how deep it is. IF not deep I'd just grind each crack a bit and fill with gel coat after it's installed so no more flexing.

To save sanding etc, once filled... you can tape wax paper over the repair to hold the gel coat flush in the crack/groove while it hardens. It's tricky getting just the right amount of gel coat in the crack to result in being flush.

[kendrickg]

I went with vinyl ester resin and made a ton of progress over the weekend. I got everything sanded and beveled, and applied 2-3 layers on the top side of some 27oz quadriaxial and to my surprise I thought it turned out great....and then it poured for 25 minutes after I left for the day!!!!

As soon as I heard it raining at my house I rushed back to the shop and the pool was soaked and the resin was just not set up yet so you could poke it and see either resin or water move under under the surface layer. I just went home assuming it has to be all ground out.

This morning it was still very tacky but this afternoon after the sun has been blasting on it the patches are rock hard and not tacky the slightest bit. They patches are basically white with only a few clear spots but they are surprisingly solid.

I still have to do two more layers underneath, so between 2 rained on layers and the two more to go maybe I don't need to grind it all out?? I mean all it has to do is have the gelcoat stick to it and hold water. Feeling a little defeated and was really looking forward to putting the grinder down for a bit.

[kendrickg]

I just bit the bullet and ground it all out, it only took 30 minutes. Im glad I did because it definitely did not bond properly and was very easy to grind out.

[Fore and Aft]

Kendrickg practice makes perfect, I think the hardest part is matching the gelcoat.
Cheers

[GordMay]

Originally Posted by Fore and Aft

Kendrickg practice makes perfect, I think the hardest part is matching the gelcoat.
Cheers

When I was in school, the teachers told me: “practice makes perfect”; but then, they also told me: “nobody’s perfect”.
So, I stopped practicing, and now, I’m a nobody.