this is a revisiting of the entry on the diver's down flag.

    that is, when are they mandatory?  it depends on state law.

you need to check your statutes to determine if/when/how

to deploy the diver's down flag.  here is a great collection of

state law sites by Chris Whitten.

    some confusion arises over the use of the Alpha flag in the

United States.  the Alpha flag is the international navigational

flag used to indicate there are divers in the water and for other

vessels to stay clear.

the Alpha Flag

     there are two sources of possible laws that could mandate use of

the Alpha flag.  they are the federal navigation regulations enforced

by the U.S. Coast Guard, and the laws of the 50 states.

    the states:  some states mandate use of the alpha flag in addition or

in lieu of the diver's down flag (for example, under certain

circumstances, Wisconsin and Maine).  so make sure to (again) check

the laws of your state regarding the alpha flag. 

    federal law:  the U.S. Coast Guard's Navigation Rules and

Regulations  covers use of dive flags in navigable federal waters

both inland and off-shore.  the easy answer is that federal law does

not require a diver to deploy either the diver's down or the alpha flag.

                diver's down flag:  the familiar red and white flag is not

                addressed

                 alpha flag:  the flag is to be flown under certain

                 circumstances from a vesel, but it is not required

                 for divers to deploy it.

    thus, the easy answer to "how do i know which flag to tow and when

to do it" is to check your state statutes.

(so when does the federal regulations mandate that a vessel fly the

alpha flag when divers are in the water?  Rules 20 and 27 provide

the answer.  if a vessel can not display three shapes (a ball,

a diamond, and another ball) in a vertical line during the day, it

must then fly the alpha flag to indicate divers are in the water.

again, keep in mind that the federal regulations do not require

divers in the water to tow the flag.  rather, the flag is displayed

from the vessel from which they are diving).