Several products are available which can be used. Epoxy is a two part petro-chemical which, when mixed, cures or hardens by means of a chemical reaction. The reaction typically is accelerated by higher temperatures. There are many types of epoxy on the market for different applications. Epoxy which is ideal for boat building is clear, has a relatively low viscosity, and cures at room temperature.
Several companies sell epoxy resins which are intended for boat building.
There are some differences between them. The most readily available is from West System. This epoxy is mixed at a ratio of four units of resin to one unit of hardener. Most manufacturers sell metering pumps to simplify the measuring of the correct amounts of resin and hardener. Several other manufacturers sell epoxy which has a mix ratio of two units of resin to one unit of hardener.