Pipe the Side

When the commanding officer of a man-o'-war or other official dignitaries enter or leave a naval vessel the side is piped in their honor; that is, according to the official's rank, a certain number of side-boys face one another and form a hollow thwartships line from the gangway inboard, and as the official passes through this line the boatswain, or one of its mates, winds (blows) his call and the side-boys salute. The ceremony is under the immediate charge of the officer of the deck.