How many letters does the top answer for “a petty officer on a merchant ship who controls the work of other seamen” have?

The most common answer is boatswain (9 letters).

Crossword clue: a petty officer on a merchant ship who controls the work of other seamen

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

boatswain 9 letters wn-def

a petty officer on a merchant ship who controls the work of other seamen

bosun 5 letters wn-def

a petty officer on a merchant ship who controls the work of other seamen