In general, cured laminated fiberglass cloth is stiff and will not flex much without cracking and breaking. This is typical when using a 5:1 epoxy resin and polyester resins. The tensile elongation for traditional 5:1 epoxy resin is 4.5% with slow hardener and 3.5% with fast hardener.
Our Totalboat High Performance Epoxy Resin (2:1 mix ratio) is more flexible than 5:1 epoxy resin and polyester resin. The tensile elongation for our High Performance Epoxy Resin is 6.7% with High Performance Slow Hardener, 7.0% with High Performance Medium Hardener, and 7.5% with High Performance Fast Hardener.