二に等とう航こう海かい士し

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Meanings

1

noun

second mate; second officer

A licensed deck officer rank on a merchant ship, below the chief mate (一等航海士). Responsible for navigation and watchkeeping.

二two, two radical (no. 7)

等etc., and so forth, class (first)

航navigate, sail, cruise

海sea, ocean

士gentleman, scholar, samurai

一いっ等とう航こう海かい士し
一等航海士 is the chief mate (first officer), ranking directly above 二等航海士.
三さん等とう航こう海かい士し
三等航海士 is the third mate (third officer), ranking below 二等航海士.

Compound of 二等 (second class) + 航海士 (navigating officer).