Marine generators are used to provide electric power to various boat systems. Marine generators are not considered necessary but help in conditions when the main engines are shut down or shore power is unavailable. Marine generators help save battery power and also use less fuel than main engines. A marine generator like all mobile generators burns either diesel fuel or gasoline. Marine generators come in all sizes and are usually rated by the amount of kilowatts of electrical current that each produces, a kilowatt being a thousand watts. Smaller recreational boats require smaller generators. A marine generator is designed and constructed to endure moisture and corrosion problems associated with the marine environment.