Diesel propulsion and generators, running gear, 12/24V DC and 120/230V AC, battery banks, inverters, shore power, solar, watermakers, sanitation, refrigeration, chilled-water AC, hydraulics, thrusters, and steering. Hands-on experience with several of these: marine diesel, generators, DC and AC electrical, inverters and battery systems, plumbing, HVAC and refrigeration, hydraulics, watermakers, marine electronics, fiberglass, and carpentry.