Ship of the line, Typically the largest warship of the civil war era.. with at least 3 gun decks.
Ironclad, early steam powered warship with defensive armor plating.
Frigate, most common size of...
"stevedore" or "long shoreman" were name for people who loaded ships. This is generally a civilian word.
Since this was posted under WW2, the only answer that fits is "sailor".