On holidays and other special occasions, Navy ships will hoist a rainbow array of signal flags up and over the mast to look pretty. (Full dress ship, [0]) The

On holidays and other special occasions, Navy ships will hoist a rainbow array of signal flags up and over the mast to look pretty. (Full dress ship, [0]) The flags for full dress ship are not chosen by the ship, however. They are mandated by an instruction and all ships have to use the same flags. ([1], paragraph 705) I'll leave it as an exercise for the reader to discern why this is so. [0]https://i.ytimg.com/vi/NCQZv5iFk-4/maxresdefault.jpg https://i.ytimg.com/vi/NCQZv5iFk-4/maxresdefault.jpg [1]http://www.ushistory.org/Betsy/images/ntp13b.pdf http://www.ushistory.org/Betsy/images/ntp13b.pdf