Fiberglass and other cloth
Most common fiber mat materials are Fiberglass, Carbon Fiber (CF) and Aramid (Kevlar). For those building competition boats, either RC sailboats or power boats CF and Kevlar can offer advantages. For the rest of us, we’re best off sticking with Fiberglass.
Fiberglass come in different qualities, textures, weaves etc. It can seem like a jungle, but here is a quick rundown of what some of the terms mean:
Fiberglass Cloth comes in a multitude of weights. The weight refers to actual weight of a square yard. The unit of measure is oz. So you’ll find 0.6, 0.7, 1.4oz. etc.
For covering planked model boats, the lightest weights work the best. They drape much better and therefore are a lot easier to work with. The down-side is that they are easy to sand through. Sometimes more that one layer is necessary.
Don’t get confused with terms like E-glass, S-glass, Hybrid Fabrics, Twill weave, unidirectional fabrics etc. For our needs, the simple stuff will work just fine.
Fiberglass Mat is unsuitable for covering the outside of a model.
Fiberglass Mat is a non-woven material. It is loose fibers that are pressed and held together with a thermoplastic binder. The idea is that when the Mat is soaked with Polyester, the solvent will loosen the fibers from the mat but stay within the applied Resin. This is what you’ll see on the inside of most molded Fiberglass items. It is easily recognized by the random orientation of the fibers.
It is the best solution if you make your own fiberglass hulls from a mold. Since there is a dissolve-phase, this mat will only work with Polyester – not with Epoxy. The Mat material comes in different weights. The Heavier weights are stiffer and thus harder to work with and more difficult to take tight radii.