most likely a very sudden event. could the boat have capsized in heavy seas and thrown everyone overboard? the Tasman Sea is a very rough stretch of water - it has always had that reputation. doesn't sound like a capsizing event would necessarily activate the EPIRB.

anyway - to be honest it sounds like the real problem is computer servers. it doesn't matter how these messages are sent ... if the server bombs out then you are toast. i wonder if the server at SPOT can go down, or if they have multiple redundancy?

Pete2