I want to start a discussion on this subject, which I have only just strated to research.

There seem to be three main types of PLB.
1. Personal EPIRB devices. Here the signal from the PLB is sent to the COPASS SARSAT satellite system and then relayed to an MRCC, like any EPIRB signal. The disadvantage is that the any remaining crew aboard the boat are not alerted about the MOB and it could take many hours before a ship is diverted to perform a rescue, by which time the casualty may have drowned or be hypothermic.

2. AIS type systems. These give out an AIS transmission from the MOB and may be picked up by the yacht on their AIS receiver. For those of us who have their AIS displayed on a chart plotter, and have the plotter turned off on ocean passages to save on power, it will take some time to fire up the plotter and get a bearing and distance to the MOB.

3. Proximity types. These work when a crew wearing a personal fob, goes out of range (20 ft) of the transmitter unit.They give an audible alarm and the unit can display boat position at the time of MOB.

Does anyone have personal experience of any of these PLBs?? Are there any other types available?

We too had the same problem with false alarms with the proximity (Raymarine) system on passage to the Lofoten Islands in 2007 and haven 't used them since. The false alarms do, however, seem to have been less frequent than those encountered by Rob. They work on bluetooth and it may be that more modern versions are more reliable.

On the ARC in 1999 a Norwegian went overboard wearing his life jacket and was picked up 16 hours later alive and well apart from sunburn. Had the AIS system have been available at that time then one would imagine the search would have been much shorter.

It 's a shame nobody yet seems to make a device with all 3 modalities built in (perhaps with strobe, whistle and marine vhf too)! Maybe there is a business opportunity there!

Simon