Why No Solid GRP?

Why almost all sailboats and catamarans that I know are made in solid fiberglass and didn't we find plans to buy in that constructive method?
Except Bruce Roberts, and even so in some models, in the sprays even don't have that method...
Dudley Dix has some also, Woods has an article for construction in flat panels.
But, all the others don't make available...
I find crab louse to work with wood, in my country pvc foam it is very expensive... I would like to see more boat plans for the amateur to build with molds male or with paineisde grp as in the sitch and glue.

 

There are thousands of designs for solid fiberglass. What are you specifically looking for? I may be able to help.

 

Some catamaran up to 7m, many designers please me, Wharram, Woods, Tennant, kendrick, the projects that I find in that size strip are to build in strip, plywood, foam, etc.
If you know some project of those in pure fiberglass inform me, the strider of Woods is also made like this, but he doesn't sell in plans for amateurs.
Another boat type that me like are the classic, Spray, Flicka 20, Amigo, Piepowder, but I don't see plans of boats as that in solid fiberglass.
In Brazil I don't find c-flex, foams of PVC cost a fortune here.

 

I am currently in Montevideo taking care of some personal business. I can sell you a design but you have to narrow down the concept. Wharram designs lightweight catamarans and a Spray is a heavy displacement monohull. Also, you need to be aware that a solid fiberglass hull is rather heavy compared to a cored one.