My grandfather somehow got into the Navy when he was only 16 and at the tail end of WW I. He was a boiler operator (shoveled coal) and eventually became a machinist's mate on the USS Wyoming (an old battleship built in the early 1900's). He had lots of photos of the ship, it's machine shop, and boiler rooms. The naval training allowed him to go to work and eventually run the University of Minnesota old power and heating plant. He was an expert pipe fitter and machinist and took me to the plant on many occasions. They had a machine shop that rivaled those on ships. He showed me how each one operated and what it did. It was fascinating even though I was pretty young at the time. He lived in a pretty old but very nice apartment building in Minneapolis. It had an older oil fired boiler for it's heating system. He was able to live there rent free in exchange for operating and maintaining the old boiler. His stint in the Navy paid off big time for him. Unfortunately he died of lung cancer. He was a heavy smoker but I have to believe he was exposed to lots of asbestos on the ship and plant as well.