The divers-down warning device must contain a divers-down symbol. The symbol is 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% longer than the height. The width of the stripe must be 25% of the height of the symbol. If multiple stripes are displayed, all of the stripes must be oriented in the same direction.
The size of the divers-down symbol depends on whether the divers-down warning device is displayed from the water or from a vessel. On the water, the divers-down symbol must be at least 12 x 12 inches in size. On a vessel, the symbol must be at least 20 x 24 inches in size.
When displayed on a boat, the divers-down warning device also must be displayed at the highest point of the vessel so that its visibility is not obstructed in any direction.
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.
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 displayed on the vessel.
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 make a reasonable effort to 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.
A divers-down warning device may not be displayed when divers are out of the water.