Chapter 5: Fuel Tanks and Fittings
Figure 5-1. Fuel
tank installationG-10
G-10 or FR-4 epoxy is a thermosetting industrial laminate consisting of a continuous-filament
glass cloth with an epoxy resin binder. First introduced in the 1950s, it has high strength, excel-
lent electrical properties, and chemical resistance. These properties are maintained not only
at room temperature but also under humid or moist conditions.
Today, what is called G-10 is usually FR-4, the flame-retardant version of G-10. The
material FR-4 can usually be used where G-10 is specified; however, G-10 should not be used
where FR-4 is specified. In structural applications on boats, this is not an issue, and either is
fine.
The mechanical properties (strength) of G-10 or FR-4 exceed that of aluminum. With a
density of 119 lb./cu.ft. (1,906 kg/m^3 ), it is only 70 percent the weight of aluminum, but it is about
3.7 times heavier than a solid plywood or fir core.