emcbride81
Contributor
Here is a nice, brief explanation of the difference in the two dive flags. I was unsure of the use of the Alfa flag, so I asked the almight Google Gods and found this.
Two flags are mandated for display in most parts of the United States and Canada when a boat or ship has divers in the water. Considerable confusion exists as to the differences between these two flags, if any, and why a dive boat has to use two separate signals. In fact, the two flags serve quite different purposes.
The 1972 International Regulations for Preventing Collisions at Sea and the United States Inland Navigation Rules provide for an elaborate series of day-shapes and lights to be displayed by large vessels whose maneuverability is restricted by the conduct of underwater operations, such as cable-laying, dredging, or conducting diving operations. Smaller vessels that are not able to hoist the complex signals used by large ships are instead required to display a rigid version of the International Code of Signals flag for the letter "A," known as ALFA, at least one meter high if diving operations restrict their ability to maneuver. Not all boats from which divers are swimming are necessarily so restricted. Generally, only vessels to which the divers are physically connected by communication lines, air hoses, or the like are affected by this requirement. It does not apply to most instances of sport diving, where the divers are swimming free of the vessel. As recent Coast Guard Notices to Mariners emphasize: "The ALFA flag is a navigational signal intended to protect the vessel from collision."
By contrast, the red and white diver-down flag, originally devised in about 1957, is intended to protect divers themselves. This flag is often referred to as unofficial or voluntary because it is not mandated by the international or inland rules of the road. This assertion is erroneous. The use of the diver down flag is required by state law or regulation in virtually every state of the Union, as well as by various Federal agencies exercising jurisdiction over waters where diving takes place (such as the National Park Service) and by the Canadian Occupational Safety and Health Regulation. Typically, the laws or regulations on the use of this flag require divers to display the flag and to remain within a specified distance of it when they are near the surface. This often means the flag is best mounted on a float or buoy near the actual dive point rather than on the boat itself. Restrictions vary from state to state, but typically include a zone around the flag where no other boats are allowed and a second, larger zone in which their speed is limited. A number of states also prohibit the display of the diver-down flag when a diver is not actually in the water.
Two flags are mandated for display in most parts of the United States and Canada when a boat or ship has divers in the water. Considerable confusion exists as to the differences between these two flags, if any, and why a dive boat has to use two separate signals. In fact, the two flags serve quite different purposes.
The 1972 International Regulations for Preventing Collisions at Sea and the United States Inland Navigation Rules provide for an elaborate series of day-shapes and lights to be displayed by large vessels whose maneuverability is restricted by the conduct of underwater operations, such as cable-laying, dredging, or conducting diving operations. Smaller vessels that are not able to hoist the complex signals used by large ships are instead required to display a rigid version of the International Code of Signals flag for the letter "A," known as ALFA, at least one meter high if diving operations restrict their ability to maneuver. Not all boats from which divers are swimming are necessarily so restricted. Generally, only vessels to which the divers are physically connected by communication lines, air hoses, or the like are affected by this requirement. It does not apply to most instances of sport diving, where the divers are swimming free of the vessel. As recent Coast Guard Notices to Mariners emphasize: "The ALFA flag is a navigational signal intended to protect the vessel from collision."
By contrast, the red and white diver-down flag, originally devised in about 1957, is intended to protect divers themselves. This flag is often referred to as unofficial or voluntary because it is not mandated by the international or inland rules of the road. This assertion is erroneous. The use of the diver down flag is required by state law or regulation in virtually every state of the Union, as well as by various Federal agencies exercising jurisdiction over waters where diving takes place (such as the National Park Service) and by the Canadian Occupational Safety and Health Regulation. Typically, the laws or regulations on the use of this flag require divers to display the flag and to remain within a specified distance of it when they are near the surface. This often means the flag is best mounted on a float or buoy near the actual dive point rather than on the boat itself. Restrictions vary from state to state, but typically include a zone around the flag where no other boats are allowed and a second, larger zone in which their speed is limited. A number of states also prohibit the display of the diver-down flag when a diver is not actually in the water.
