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Scuba Diving Warning Flags
The familiar red-and-white dive flag was invented in the early 1950′s by Denzel James “Doc” Dockery from Michigan. In 1953, he followed instructions published in Popular Science magazine for building his own scuba unit, and began experimenting with ways to make a living in the brand new sport. 
In the course of his work, Dockery found that he needed a warning flag to keep boaters at a safe distance. Since Dockery had served in the U.S. Navy, he was familiar with the red signal flag that’s commonly used to connote danger. The Navy’s “bravo flag” is solid red. In order to make his flag distinctive, Dockery decided to make a modification. He asked his wife Ruth to sew a white stripe across the middle of it. They put their stripe horizontal, right down the center from left to right.
Unfortunately, there was a problem with their design. It was the national flag of Austria. They needed something else. A vertical white stripe was out since that’s the Navy’s numerical number 7 signal flag.
After doing their homework, they decided to make the stripe diagonal. Ruth sewed it from the upper-left corner to the lower-right corner. The dive flag, as we now know it, was born.
Another boost came from Skin Diver magazine. They mentioned Dockery’s flag in a September 1957 editorial and asked their readers to send in their thoughts on the design. In February 1958, they declared the discussion closed, with the “Michigan Divers Flag” as the reader’s choice. /p>
In addition to promoting it among divers, Dockery worked to get the flag officially recognized in his home state of Michigan. He was successful, and Michigan became the first state in the union with a diver flag law. Now, thanks to what he started, the federal government and almost every U.S. state officially recognizes Dockery’s flag as the official warning sign of a diver down.
Practice about this choice of flag is however, not uniform worldwide. In some countries, the practice is to use the blue-and-white A-flag. As a code signal the international Signal flag A (letter ALFA/ALPHA) has the meaning of “I have a diver down; keep well clear at slow speed”, used to indicate the presence of a diver in the water, and is more commonly employed in Europe and the British Commonwealth, including countries such as United Kingdom, Ireland, Israel, Australia, New Zealand, South Africa, and Kenya. A rigid replica of the ‘A’ flag is required to be displayed by any vessel engaged in diving operations, when restricted in her ability to manoeuver, if the size of the vessel makes it impractical to display the shapes and lights required by the International Rules for Prevention of Collisions at Sea (IRPCS) Rule 27. The ALFA flag is a navigational signal intended to protect the vessel from collision.
Although the presence of the ‘A’ flag may afford some protection for divers in the vicinity of the vessel displaying the flag, the intention of the rigid replica required by IRPCS Rule 27 (e) is to warn other vessels of the danger of collision. This marks a distinction between the ‘A’ flag and the the red and white diver down flag.
References: Dive-Flag.com and other research.
- Footnote
1. What is today called the “bravo flag” Dockery would have called the “baker flag.” This is simply a reflection of the difference in the way the U.S. Navy refers to the alphabetical signal flag for the letter “B.” In 1956, the Navy adopted the international standards for the phonetic alphabet, and therefore started using “bravo” instead of “baker” when referring to the letter B.
2. See “1957 – Divers Down” in Skin Diver’s Nuggets of Yesteryear by Tamara Collins.
