how water resistant are they, the tags in particular? doesn't seem to say on the maplins page. would range be an issue? I think the range could be an issue, in conditions that would be generally conducive to a MOB, the stated range might be exceeded and then you're down to guess work... but in the dark etc could be useful for pinpointing the casualty...
Interesting but you would realy need a device that would alard if a signal was lost (fail safe)
I have oftain thorght that an old radio direction finder could also be used to find someone who has gone over the side using some small VHF transmitter, but again this would not be fail safe
Personal transmitter, receiver alarm sounds if our of range or panic button pressed. Can be linked into engine stop (for solo motoring - can you swim as fast as your boat?) and emergency tx. Cheap and simple!
(oops, sorry - must learn to read before posting - it doesn't use RDF set but is self-contained system)