Bathtub Question

I feel a bit like a moron posting this above the Observer Effect thread, but here goes-

I had a crack in my fiberglass bathtub that I patched using a fiberglass repair kit from a boating store. After sanding, I painted the patch and it seems fine. Between the area of the tub and subfloor (?) I used insulating foam so the floor beneath the tub feels pretty firm.

As far as the crack is it better to bath in the tub or shower? I’m not a large person, so would weight be more evenly distributed and less stress placed on the crack with a bath? Or, because of the weight of the water, would taking a shower be better?

I know this is a short term fix, but I don’t want to have to replace the tub immediately.


I cannot answer the water weight vs. distributed weight, but if you used a good quality fiberglass repair kit from the boating store, it should hold up fine under showering conditions.

I used a repair kit meant for below the water line application about 4 years ago and it has held up perfectly for 4 years. My weight was as high as 240 lbs. This shower is used twice a day as it is in the Master Bedroom.

What product did you use for the repair? Was it for cosmetic sealing or below waterline use?


If you are going to replace the tub before long you should have no problem. Long term, the crack might grow because of a stress concentration at the ends. Of course the “splint” you have on it might prevent this. Next time this happens, drill a small hole at each end (maybe 1/8") to distribute the stress better and then patch it.

I did that! I drilled a little whole on either side of the crack, then filled the hole with Evercoat filler. Then I used Bondo fiberglass repair kit. The crack was on the floor of the bathtub, that’s why I’m a little concerned.

The Bondo probably is not for below waterline use, I believe it is usually cosmetic repairs.
If the tub starts leaking again, ask someone in the store for a fiberglass repair that is meant for below the waterline use. It will be small and fairly expensive, around $20, but it should do a great job.

It was very smart to go to a marine store and not Home Depot, I doubt you would have found anything at Home depot that would stop the leak. Are you a boat person?


The crack you patched over may only be a stress crack in the gelcoat finish and not in the fiberglass laminate. In my business, I see that a lot. The patch may not have even been neccessary. In fact most likely not neccessary.

Gelcoat is very brittle, much thicker than paint and will crack with the slightest flexing while the fiberglass structure underneath will maintain structural integrity.

I seriously suggest you look for a fiberglass repair business in your area to first evaluate your problem and give you an estimate for restoration. You will find that this option could be a lot cheaper than tearing out the tub and replacing it.

No, I’m not a boat person! I’m not even very handy but I watch way too many do it yourself shows and try to tackle things I probably shouldn’t.

It’s definitely a crack because it goes all the way through. I don’t know how it happened, but I think I did it when I painted and put a ladder in the tub. Stupid, I know! It’s a very old tub that’s one piece and must have been put in the house before the walls were up.
I’m defiitely going to call about restoration first.