Conclusion. Eugene and Spencer attempt to turn a riding mower engine into an outboard motor strong enough to power a salvage barge, which they plan to use to locate a lost sawmill in an abandoned underwater town, where they hope to retrieve any vintage steel left behind.
Eugene and Spencer decide to build a solar-powered hot water heater out of salvaged pipes and old beer cans, but first they need to construct a chainsaw chopper for their friend who has the supplies they need.
Season 4 begins with Cowboy asking Eugene and Spencer to fortify his compound in preparation for the end days. Included: The guys construct a wood still to make sure that their neighbor will have fuel no matter what.