The Seawind hull is made out of ABS - this is a material that is widely used in plumbing automotive and many other industries. There are ABS "solvent cements" sold and you can repair ABS with Fiberglass mat and two part epoxy - Making a copy of the hull is not going to melt the ABS if you use the correct materials, but that is an extreme and unnecessary path to take to repair your boat's hull.
I use fiberglass on my ABS boats to reinforce their weak areas, and have never had an issue. You need to select the right materials, like using a slower curing epoxy, as they don't generate as much heat as the fast curing ones do.
Check out 30 minute cure time 2 part epoxy, practice with it first - use very light weight mat so you don't add excessive weight to the hull. Also be aware of keeping the boat balanced, not adding weight to only one side etc.
A little research and some practice. Fiberglass materials are found and most good hobby shops. We have chatted about your boat on another forum, and I was under the impression you were futher a long on your deck rebuild - not matter - you should find some good support either side of the pond.
Windchaser