Git Rot is an epoxy resin. You could probably use another kind of epoxy resin from west marine. I think the reason that Git Rot is so recommended is because you don't have to know a darn thing about mixing epoxy to use it. It comes in two parts, you add the catalyst to the provided bottle, shake, and wa-la you're ready to go. Plus, it's relatively inexpensive. But, I'm no expert. I used the Git Rot for a delam repair and was pleased with the results and ease of use.
Italianhobie,
You may want to search on-line for a provider before you go through all the trouble of having someone here in the states send it to you. Here is one place that distributes it.
http://www.jamestowndistributors.com/us ... atch_type=
You may even want to try somewhere that sells fibergalss bathtubs, it's also used to repair them from what I understand. Good luck and post again if you don't have any succes finding it.