二に等とう航こう海かい士しにとうこうかいしMeanings1nounsecond mate; second officerA licensed deck officer rank on a merchant ship, below the chief mate (一等航海士). Responsible for navigation and watchkeeping.See also: 一等航海士 (いっとうこうかいし)彼かれは大おお型がたタンカーで二に等とう航こう海かい士しとし