Steam, Steam and more steam
My maternal grandfather was a Chief Engineer in Steam, a Lt Commander Engineering RNR in WW1 on destroyers and in peace time and WW2 he was a Chief Engineer with Elders and Fyffes.
The stories he told me about those engines and how they were the best in the world. How they tested the temperatures of bearings and other bits of machinery by touch, knowing exactly where and when to touch a moving part.
No temperature gauges just personal judgement and sound knowledge.
You are right, those men earned their money in pretty awful conditions. He was torpedoed in WW2 on a Fyffes ship, was down below and got washed out of a hole in the ships side, tearing his leg open from knee to ankle on the broken steel. It never healed properly and he was in and out of hospital all the time when I was a kid with ulcers from the fuel oil that had got in the wound.
He never tired of telling his little grandson ( me ) about the sea and his engines and his little grandson never tired of listening to him and went to sea too when he was old enough. However I went on deck, because I wanted to drive. Lazy or what ?