It masks me wonder if there is a market for automatic sensing hydro-electronic sensors integrated in sailors / fishermen's clothing. The idea is if the sensor is in contact with some amount of water for 90+ seconds, start a count-down to chirp an emergency radio beacon.If the user doesn't over-ride the count-down, via a button somewhere in clothing, it starts sending a distress beacon, allowing for rescue within hours most likely.
The reason for the automatic element is if someone were to be knocked overboard and unconscious. A similar concept can be thought of regarding the firefighters PASS device:
The one I wear when at sea cost $400 or so plus a $50 annual fee.
The main benefit of a PLB is to assist the vessel you fell from in finding you - unless you had the good luck to fall overboard near a heliport in decent weather or in a busy shipping lane, the PLB will (mostly) not be able to get a rescue effort by any other party under way in time.
Well most of them were picked up by another fishing vessel, probably because of a VHF radio distress call and not a ELB/PLB. Those devices often depend on reception by overflying commercial aircraft, which are bound by international treaty to monitor the frequencies and forward reports to land-based authorities. Others use satellite reception. Such beacons are the method of last resort when far from land and not in the company of other nearby vessels, and it can take quite awhile for responders to get the report and make it out to the area.
Very cool idea, but I doubt there's money to be made, except perhaps by targeting recreational water-goers.