We are discussing on here whether you should have a (possibly GPS enabled) PLB for crossing the Channel or North Sea, in addition to the ELT. For flights lasting less than an hour (sometimes even mere minutes) over water. I would have thought that having a GPS enabled PLB (or two) on board for oceanic sailing would be a given. Maybe a satphone as well. At the very least, something to rig up a backup VHF antenna.
Most yachts intending to cross oceans these days would have an EPIRB, GPS chart plotters, SSB or a sat. phone and an emergency VHF radio. All are requirements for entry in the ARC (the rally for cruisers crossing the Atlantic and held every year). It of course doesnt mean to say all yachts carry everything or even some carry nothing. Sat. phones are still considered expensive as are SSBs so there are certainly some yachts that would have neither. VHF propagation at sea level is essentially line of sight so in the middle of an ocean another vessel to relay is your main hope.
You might well put together a jury rig so reliance on the engine is not total.
One suspects (I have not read the reports) that he must have communicated his distress in some way for the aircraft to be looking for him in the first place. Unlike a "downed" aircraft you will almost never stay still in the ocean (although with a drogue parachute you will drift very little) so your initial GPS fix will change over time. His original point of distress may have been somewhat removed from his position 24 hours later, although yachts are usually very pleased with a full rig to make anywhere near 200 miles in a day. He might have typically motored at between 6 and 8 knots so never the less he could have been a considerable distance from his original point of distress.