E-flares—battery-operated bright lights that automatically flash the Morse code S-O-S distress signal—can replace red handheld pyrotechnic distress flares as required nighttime distress signals. Are there restrictions, and are e-flares as effective? I talked to US Coast Guard regulators and rescuers to answer these burning questions.
In US inland-water collision rules, a rapid-flashing white strobe light is a distress signal, but it isn’t a distress signal under international COLREGS. E-flares, which blink a continuous Morse code S-O-S pattern—a distress signal in all waters—also meet Coast Guard requirements to replace the common handheld flares.
“Whether it’s electric distress lights, pyrotechnic flares or orange flags, if they are Coast Guard-approved or certified visual distress signals, they are equal in meeting the carriage requirement,” says Joseph Carro, who works in the Coast Guard’s Office of Boating Safety. This includes all navigable waters of the US, as well as Coast Guard enforcement aboard US-flagged vessels in international waters.
There is a caveat, though. Red handheld pyrotechnic flares fulfill both nighttime and daytime distress-signal requirements; e-flares only meet the nighttime requirement, so a separate daytime signal is needed.
Two Considerably Different E-flare Standards
Back in 1979, specifications for “S-O-S Distress Lights for Boats” became US law. The Coast Guard hoped to foster new technology to replace pyrotechnic flares.
“The new eVDSD [e-flare] lights came into their own with LED technology that met those  requirements in a cost-effective manner,” Carro says. But that 1979 spec was essentially a wish list for technology that didn’t exist. Performance claims—such as 10-mile visibility—are theoretical calculations. In a seven-year study that included real-world testing, Carro and his colleagues determined that e-flare light specs proved equivalent to handheld flares. Those results were published in 2018 by the Radio Technical Commission for Maritime Services. (The RTCM also sets standards for EPIRBs and other gear.)
White S-O-S Lights
Most current e-flares meet the older 1979 standard. These small, waterproof devices carry a very bright light, but not in all directions. Their lens focuses along the horizon when floating and out the end for pointing toward rescuers.
Surprisingly, many LED lights, including those on e-flares, are not visible to Coast Guard night-vision gear. “We do a combined scan. We’re looking through night-vision goggles, but every minute or so we scan without them,” says Lt. Rob Turley, a Coast Guard helicopter pilot based in Cape Cod. “Some lights we can’t see until we lift our goggles.”
Two-Color S-O-S Distress Lights
Currently only offered by Sirius Signal, two-color S-O-S lights—built to the newer 2018 specifications and effectively much brighter—also fulfill Coast Guard distress-signal requirements. The 2018 RTCM standard is also considerably more robust—some say overly so—than the older 1979 law. The red-orange “S” dots and cyan “O” dashes perform better nearshore than white lights against strong background lights, and they’re less easily confused with red (port) side boat navigation lights than red flares.
Their light spreads evenly across an entire half-sphere, and an added near-infrared light shines in the Coast Guard’s light-amplifying night-vision gear (but not in FLIR thermal imagers).
Handheld Red Day/Night Pyrotechnic Flares
Handheld pyrotechnic flares are at least tenfold brighter than e-flares—SOLAS flares are 300 times brighter than e-flares—and particularly visible to both thermal imagers and night-vision gear.
Orange smoke flares are the gold standard for daytime signaling. “Even on a windy day when smoke follows along the ocean’s surface, we can still see plumes of orange smoke, and from that, we’re able to find a person in the water,” says Lt. Billy Martin, a Coast Guard airplane pilot also based on Cape Cod.
But orange smoke flares are not required for -recreational boaters, and while red handheld day/night flares are quite bright and emit ordinary smoke that helps attract attention, they lose luster in daylight.
A 3-foot-square orange flag, the only other daytime signal that meets Coast Guard requirements, can wave on a boat hook indefinitely, giving it an edge over three red handheld flares that provide just nine total minutes of signal time. But stormy skies or waning daylight mitigate a flag’s ability to attract attention.
A registered EPIRB or PLB, or a VHF radio with its DSC distress function connected to GPS and registered via an MMSI, automatically alerts rescuers. That leaves visual distress signals—whether flares, flags or S-O-S lights—to guide those rescuers over the last mile. Signal duration is more important than distance seen, which distinctly favors the continuous, unattended S-O-S from e-flares or waving orange rescue flags.
On the other hand, visual distress signals attract nearby boaters for immediate assistance. It’s hard to imagine nearby orange smoke or a red handheld flare going unnoticed.
Read Next: Marine Signal Flares and Distress Signals
So, are e-flares or pyrotechnic flares best for you? Probably both, Carro says. “What works best depends on where you are and what’s going on. When you’re in distress, you want to have many options to help us find you.”