|The little float coat is sort of cute, until one contemplates its intended use.|
My wife recently returned from a delivery (see previous entry below) and stood a few midnight deck watches. I was insistent that she bring a tether and harness from the currently beached Alchemy as I really feel it's important to stay with the boat. And yet various technologies aimed at the recreational boater seem, in my view, to foster a false sense of security by implying that transmitting a GPS co-ordinate or a homing signal from your person to a boat or a satellite is going to keep you alive.
While I would certainly place these location devices in the "better than nothing or a waving penlight" category, and while I bought an ACR ResQFix personal locator beacon (PLB) in 2007 for myself and my wife once we started to crew for others in salt water, I try to avoid subscribing to the illusion that the danger of falling off a moving sailboat away from land is somehow now less dire a prospect than Captain Ahab going for a whale surf.
PLBs are meant to assist SAR personnel to find you. EPIRBs are meant to assist SAR personnel to find your boat or your liferaft. The increasingly popular SPOT Messenger Service seems a weaker version of either, but can be used to track movements.
The "self-rescue" systems I find quite specialized are exemplified by the Sea Marshall brand whereby you have a short-range locator beacon on which a shipboard direction finder can zero in.
I can see divers, oil rig workers, trawler deck crew and the military really going for these devices. A cruising couple, not so much. The trouble, as I see it, is that these stand-alone systems are really expensive, and the situations in which a sailboat can effectively self-rescue a crew are typically few. Picture a cruising couple on a downwind run in a gale. A preventer line parts, the boom crash gybes, and the PFD-wearing...but untethered...husband is knocked in the head and right over the lifelines. The beacon is activated hydrostatically, and the husband's PFD also inflates.
Now you've got a guy in 20-foot waves with a head laceration, perhaps a cracked skull, very dazed or totally unconscious, in the water. He isn't sinking, but he isn't swimming, either, nor can he more than reflexively keep his head out of the water and the breaking spray, so he might drown in his PFD anyway. Knowing exactly where he is makes him no safer at this stage. Far better he had stayed on the boat in the first place. This may seem self-evident, but like the old saying about "don't get into the life raft until you have to step up to it from the boat"...implying that a half-sunken boat is intrinsically a safer place to be than a fully functioning life raft...a lot of people seem to think that gadgets will save them, instead of just marking the location of their corpses.
Back to the scenario: The wife is hypothetically a great sailor in her own right, but she has to bring the boat about in a gale and sail or, more likely, motor directly into the wind in very challenging conditions. She is alone, distraught and fighting to keep a course. Nobody falls off in calm weather at noon within shouting distance, do they?
Then what? Motoring in heavy seas next to an unconscious floater is a good way to kill him off entirely through blunt force trauma from the hull or by beheading him with the prop. I haven't even got to the idea of dislocating his arm on a fast-moving "rescue line" or taking out his eye with a boat hook...assuming you ever get that close...and has he regained consciousness yet? This is assuming you can even keep him in sight...I hope that PFD has a strobe! Or that it isn't blackest night...
My point is that finding someone, even someone uninjured and conscious, is no guarantee of getting them aboard a sailboat in heavy weather. Few autopilots are going to work predictably in such conditions, and the boat itself can become very dangerous going to weather.
If the water temperature allows it and one is sailing coastal, the odds are better to let SAR handle it, in my opinion, but I believe the best option is to tether on religiously in any situation in which you are unlikely to have another crew save you. That means "much of the time on passage", unless motoring through a calm.
Airbags didn't replace seatbelts, nor do they permit terrible driving. If you work from the baseline that falling off a moving boat is a potential death sentence in every instance, you may invest less in "spot the corpse" technologies and more in behaviour modification on deck.