Recently a reader questioned how useful a handheld VHF radio may be if you end up in the water needing to call for help. He wrote, "Do you have any info on the range and effectiveness of your handheld DSC radio when you are in the water? Low power, small antenna, very low elevation - it can't be good." Following are my thoughts on this.
Good questions. I've never been able to find scientific research on handheld range from, say, a foot above the water's surface - but since VHF is line of sight, being low in the water shouldn't be a problem to reach any boat you can see - or to reach a tall Coast Guard antenna. One of the nice things about DSC is that the emergency call signal is digital, not analog - and thus is much less susceptible to static, garbled speech, other sounds, etc. And the unit will keep sending the signal over and over, increasing the odds for getting through (and if the VHF does not have GPS, allowing the Coast Guard to triangulate position).
For me, the real advantage is that with VHF DSC you may reach a nearby boat. If you had only a PLB (or EPIRB) to call the satellites for help (a wonderful resource), another boat could pass very close to your location without seeing you and without you being able to contact it, while you're waiting for the satellite system to notify search-and-rescue services and for help to be sent, perhaps from some distance. Ideally, you'd have both a DSC GPS VHF and a PLB clipped to your belt for the best of both worlds - though I doubt most sailors would double up their gear (particularly for every crew on board - any of whom could go overboard).
I look forward to the day when some manufacturer makes a single unit that sends both VHF and satellite mayday signals (and maybe AIS too!) - so that everyone, everywhere, knows where you are and that you need help.