The official legal emergency call by a captain if he is ordering his crew (and passengers) to get off/jump off the ship in an emergency is simply "Abandon ship!" I assume this is simply to save time. If your ship is sinking you want to shout as few words as possible to alert everyone to the danger. The sentence you posted simply has "Abandon ship" but not in direct speech. Effectively it says '... the captain gave the order "Abandon ship" '.
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