Fiberglass tubs are made exactly the same way as fiberglass boats or car bodies.

Believe it or not, the first step of manufacturing a tub, boat or car body is to paint it, then they build the body part. Sounds strange but thats true.

The begin with a mold of the finished product. The first step is to spray "Gel Coat" which is the finished color material on the inside of the mold, then they build it up with layers of fiberglass cloth, matting or roving (a loose chopped fiberglass material) and resin until they get the desired thickness.

Once they have the thickness the mold is set aside to cure.

When the curing is complete they attach a high pressure air hose to a nozzle on the bottom of the mold and inject air into the mold. The air entering the mold lifts the finished piece out of the mold and ready to be shipped or moved to the next point in the assembly process.

In is doubtful if you really need any real fiberglass repair. If you examine the damage site carefully you will notice that the finished gelcoat is about 1/16" to 1/8" thick.

If you go to an auto parts store or a marine supply store you can find a "Gel Coat" repair kit. Most Gel Coat in the repair kits is white and they give you some pigments that you can add to match your color. You can fill the spot with the gel coat, then trowel it even with the surrounding surface and allow it to dry. When its dry you buff it out with the super fine emery paper in the kit and you should be able to create an invisible repair.

If you would like to see the process done a couple times before taking it on for yourself, go by a local boat dealer and explain what your doing and ask if you can watch their mechanic make a gel coat repair.