Chapter 43 Hark!
A sailor named Archy on the middle-watch hears something and warns that there is someone down in the after-hold that has yet to be seen on deck. Cue the spooky music.
The sailors are filling the scuttle-butt. Now most frequently used to mean rumor or gossip, scuttle-butt was originally a term for a water butt on the deck of a ship, providing drinking water. Butt: a cask used for wine, ale, or water; a liquid measure equal to 2 hogsheads or 126 gallons. Hogsheads? Yuck! My etymological inquiry ends here.