hole due to buldging at the deep end due of Fiberglass pool

Hi everyone,
I obtained a fiberglass pool a few years ago that had a hole at the bottom due to the previous owner removing all the water. I tried AB epoxy to seal the holes for the last 2 years but it didn't hold and I would lose water and clarity due to ground water/dirt contaminating the pool. Also it feels like there is water under the floor as it shifts when you walk on it.

So I emptied the pool a few days ago... put 7 garbage cans full of water on the bottom and braced the walls. My plan is to cut out a rectangluar 1"-3 buldged section at the deep end -right now its just a cut with 3 drilled holes (I used to suck out the water last year) all filled with Ab epoxy, suck out the water, fill the hole with leak stopper hydraulic cement flush with the old fiberglass, and lastly sand the 1-2" of the pool adjacent to the cut-out section down to the fiberglass in prep to cover it with 3M fiberglass mats with fiberglass resin/hardner

Any thoughts? Please chime in.
 
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Etchase

Active member
May 22, 2019
26
Hawaii
If I was repairing a boat I would want to grind away the existing fiberglass about 3inches around the hole to provide a good strong bond. I would not just overlay a single layer of Matt, but build up several layers of Matt right through the full thickness of the hole. No cement. I would use polyester resin and finish with a water proof gel coat. Lots of information on boat repair, since lots of boats get damaged. Surf board shops will direct you to great fiberglass suppliers, and might know an experienced fiberglass guy.
 
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frogabog

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Jul 16, 2010
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Portland, Oregon
+1 on what @Etchase says. Boat fiberglass repair methods are heavy duty (no one wants a boat to sink), and should work well on your hole. Go with a straight up multi level fiberglass matt and resin patch/repair method. (check YouTube). You could even color the resin or gel coat to match your current color.
 
1st of all thanks for the help Etchase & frogabog.

I drilled a hole to let the water out and I believe I drilled and sliced through the layer under the fiberglass and a slice (top in picture)

What should I do now?

1-Cut a section of the blue base layer out and fill with cement and then proceed to grind the fiberglass and start to lay Matts.
2-Fill the hole with Cement and cut the slice into a tirangle and fill it with cement and proceed as above.
3-Something else?20190826_191318.jpg20190826_191318.jpg
 

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frogabog

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Jul 16, 2010
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Portland, Oregon
Sorry, I don't know the first thing about fiberglass pools or what's under the fiberglass. I really only know fiberglass and boats... Hope someone has an idea for you!
 
Sorry, I don't know the first thing about fiberglass pools or what's under the fiberglass. I really only know fiberglass and boats... Hope someone has an idea for you!
Once I removed the section from the top cut to the bottom hole I believe the the bottom layer is fiberglass and the top is a mosaic / gel coat. I tried filling the gravel underneath with cement as of right now it appears to be loose gravel however as of right now that dosn't appear to be setting (d/t to the ground water?).

If it doesn't set I will try a hard epoxy such as AB epoxy under the fiberglass & proceed sealing it.
 

Etchase

Active member
May 22, 2019
26
Hawaii
Hope the cement sets for you. If you can get some matt thru the hole to the concrete side of the hole it might help hold the fiberglass repair in place. They also have loose glass fibers that you can add to the epoxy to give it some added strength. Good luck.
 

sktn77a

Gold Supporter
May 16, 2010
1,371
Chapel Hill, NC
I don't think fiberglass pools generally have separate layers, unless the gelcoat layer has separated from the fiberglass (but it doesn't look like that). It may be a main drain plumbing chase or a structural chase. I think the boat repair approach outlined above should work.