Ahoy - The traditional hailing call. Hoi is still the blind-corner signal of Venetian gondoliers, apparently having come into use in the early days of these craft. It was once the dreaded battle cry of the Vikings, and appears in Middle English and Old French.
Bum Boat - A small harbor craft used for peddling to, or ferrying, ships' crews, still extant in some ports. The term applied originally to boats so used on the Thames River, at and below London in the XVII century, and probably came from the Dutch word, bom, bluff.
Irons, In - Said of a sailing craft when caught dead isnto the wind and unable without extra sail-handling to fill her sails on a new tack. The term sometimes is used for a steamship that is badly trimmed or so lightly loaded that her propeller and rudder are ineffective. The origin of the term is uncertain; it could be from the sense of being in shackles, and unable to move.
Rose Box - The filter or strainer on the suction side of a bilge pump. A good example of sailors' whimsy; you can imagine how rose-like the scent and petal-like the solid matter collected.
Information is from the book "Origins of Sea Terms" by John G. Rogers
copyright 1985 Mystic Seaport Museum, Inc. and available from BlueJacket.