New Product 1
Here's a normal looking peice of Stitched Bi-axial Glass. It's intended for use with Epoxy resin which doesn't disolve the starch used to hold Chopped Strand Mat (CSM) together, so stitching a number of different weaves together has become the norm for epoxy GRP. (You can get 'Tri-Ax' too, and a mix of glass/CF. How much money you got?)
It's much nicer to lay than CSM in Polyester. The resin is squeegeed into the glass rather than stippled in with a brush. Most people use the little plastic rectangles used to apply bodyfiller. It's sticky and doesn't have a liquid phase during cure. It's also lighter and much stronger.
The only snag is that it lays very flat, it's easy to get a 400gm. sheet less than 1mm thick. This is good for strength and weight but not very stiff as a surface. This makes skinning carved foam an attractive solution. The load spreading ability of the foam means that even 300gm is quite stiff enough for non-impact surfaces and internal surfaces can be covered in 200gm cloth. It's also easy to carve the foam away internally, leaving ribs or other stiffening shapes where needed.
But carved foam is an esoteric prototype-making technique. You're not going to see it in production GRP, except maybe in post-cure fills. And it's certainly not much use for making a 30 metre boat.
For the latest answer go to "New Product 2" in the Monoliner images. It may look like normal Bi-Ax, but it aint...