Sunless Sea Best Engine: Fulgent Impeller & Tireless Mechanic Story (Element of Dawn)

Ahh, the Fulgent Impellor. A very long, very complicated quest, involving all sorts of running all over the map, and upgrading of ships. You&need an Element of Dawn, cargo space for 42 items (plus fuel and supplies), the Unsettling Sage from Wisdom and the Mechanic&Secret from Frostfound. None of these are easy things to do, but the engine is excellent, and totally worth it.