DIVER'S FLAGS
You will be shown 3 flags in class that are used by divers:
Every letter of the alphabet is represented by a colored flag. Almost all of them have a dual meaning. Each represents a letter, and most have a second meaning. These flags are recognized by captains of ships throughout the world.
The Alfa (sic) flag is white and blue with a triangular piece missing from the blue front. It represents the letter "A" as well as meaning: "Diver Down; Keep Clear." This flag must be flown from vessels that have diving operations going on in international waters, coastal waters, and other waters where commercial and international shipping is taking place.
The red flag with a diagonal white stripe from the upper mast to the lower outer corner was specifically for divers in the United States. The flag is not an official flag. It is the most common flag flown by divers in the USA. It is now used in many areas of the world and may be flown with the Alfa flag. It generally means there are divers within 100' of the flag. Exactly what legal requirements are connected with the use of the flag is determined by the law in each State. In New York State, Section 45, 1a of the State Navigation Law states that unless you are the vessel that is involved in diving operations, boats must stay at least 100' away from the flag.
There are many pleasure boaters that do not have a clue as to the meaning of any of the divers' flags. Just because the flag is flying does not completely protect the diver. It is important for divers to make sure local boating training courses, such as those conducted by the US Coast Guard Auxiliary, include information on "Diver Down" flags.
The Papa is a blue square with a white square in the middle. When the flag is displayed it means the vessel is about to sail. This flag has been used to bring divers back to the surface and discontinue diving operations. When the flag is up, the tenders realize the end of diving has been signalled and start the divers toward the surface. Sometimes large cruise ships will tell their departing tourists to return to the ship when the Papa flag is hoisted to the top of the vessel.