All hands means every member of the crew, called on deck. All hands on deck, all hands to the pumps.
A hand is a crew member, which is why the phrase counts people by their hands. It is now used ashore for any effort that needs everybody at once.
1phraseall handsEvery member of the crew, called on deck.
“It was all hands on deck for the last two hours of the passage.”
all hands is a phrase.
Practised in Sea & Sailing