Gelcoat will no do you any good at all. It is not a barrior to water.
I have spoken to many many people who have ground their hull.
Not one has ever indicated they would do it again.
Some kind of blasting, usually soda blasting or sand blasting depending how deep you need to go is the way to go.
The lesson from the Icarus story is not about human failing.
It is a lesson about the limitations of wax as an adhesive.
If you have an engineering problem solve it.