Dive Flag 101: Diver Down Flag Rules for Boaters and Divers

Here is what you need to know about dive flags, whether you're driving or diving.

May 19, 2022 By Blair Wickstrom

Soon it’ll be time to dust off your flippers, check your masks for dry rot and your snorkels for leaks. You’ll also probably need to hit your dive flag with some bleach if it’s been sitting deep in a so-called dry storage compartment since last August.

As for those of you for whom this doesn’t seem to apply, meaning you don’t dive, please don’t stop reading. This seminar is primarily for you.

“You simply won’t ever be able to forgive yourself if you run someone over,” warned Brian Rehwinkel, Boating Safety Coordinator with the Florida Fish and Wildlife Conservation Commission (FWC). “A citation is one thing, having to live with knowing that you killed or dismembered someone is an altogether different thing.”

Fortunately, not many divers do get run over, but incidents that occur tend to be very serious. Crippling or lethal injuries may result from propellor strikes. Diver Rob Murphy, of Palm Beach Gardens, lost both legs to a boat strike off Southeast Florida in 2009. Recently, Rob was one of about 70 people who responded to an informal survey I posted on my Facebook page. I asked three questions pertaining to the divers-down flag.

dive flag rules — Know the rules of the road with respect to this potentially life-saving symbol.

The answers I received indicate that we’re lucky people err on the side of caution with respect to the divers-down flag rules. People were close with their answers, but practically no one, PADI Instructors as well as charterboat captains, answered all three questions correctly.

Here is what you need to know, whether you’re driving or diving:

Boaters must make reasonable efforts to stay at least 300 feet away from divers-down warning devices in open water and at least 100 feet away in rivers, inlets, or navigation channels. Boaters approaching divers-down warning devices closer than 300 feet in open water and 100 feet in rivers, inlets, or navigation channels must slow down to idle speed.
Divers must stay within 100 feet of a divers-down flag or a buoy within rivers, inlets, or navigation channels and within 300 feet on open water.
On a vessel, the divers-down flag must be at least 20 x 24 inches in size. And the flag must be displayed at the highest point of the vessel so that its visibility is not obstructed in any direction.
On the water, the divers-down symbol must be at least a 12 x 12 inch flag on a float. If the divers-down symbol is a buoy, the buoy must have three or four sides with the divers-down symbol displayed on each of the flat sides. The buoy must be prominently visible on the water’s surface and can’t be displayed on the vessel.
If the divers-down warning device is a flag, the divers-down symbol must be on each face and have a wire stiffener or be otherwise constructed to ensure it remains fully unfurled and extended, even when there is no wind or breeze.
A divers-down warning device may not be displayed when divers are out of the water.

A common misunderstanding in my survey pertained to diving marked channels. People can legally dive in marked channels. But as Rehwinkel pointed out, “Use your best judgment; if you don’t need to be in a channel, don’t dive in a channel.”

Survey respondents were also unclear regarding the legal size of the flag, and whether it’s permissible to make your own. You can, in fact, legally make your own flag, but you’ll have to get out your calculator. Rob Murphy flies a 3 feet by 5 feet flag now. But to do this, the flag must still be a red rectangle or square with a white diagonal stripe. If the symbol is a rectangle, the length may not be less than the height or more than 25 percent longer than the height. The width of the stripe must be 25 percent of the height of the symbol. The flag must also have a wire stiffener.