SIGNALING: The most effective signaling device is an emergency position-indicating radio beacon, or EPIRB (pictured above), which notifies rescuers via a global satellite system that you're in trouble. The next best device is a very-high-frequency (VHF) or single-sideband (SSB) radio. When making a Mayday call, calmly and clearly state your GPS coordinates, the nature of your emergency, a description of your vessel, and the number of people on board. Once you believe rescue is close at hand, use visual signals like aerial flares, smoke, and dye markers. Don't shoot a flare unless you know someone is close enough to see it, and aim it over the water so you don't risk setting your boat on fire. Use a mirror in daylight, flashing it at the horizon.