"Bravo Zulu" is the maritime way of saying "Good job!"
The "B" (or Bravo) signal flag and the "Z" (or Zulu) signal flag are raised simultaneously to signal to the skipper of the other boat that they had done a good job in the endeavor, whether a race, or a maritime battle, or other exploit, a skipper seeing the command vessel, or the committee boat (in racing), hoist the B & Z flags know they are getting a nice "atta boy"

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