He got his mayday out SAR and coast guards (knew the he was in the Solent) were called out and yet it took almost an hour to find him (almost dead).
I'm about to buy a Fastfind Plus PLB, incorporating GPS for this reason. Position to 30m, satellite alerting within 3 mins, weight 300g. Amazing!
In the cub, my rationale is to keep sea crossings short, wear an immersion suit and high quality lifevest (Switlik helicopter crew vest) and carry a fastfind and portable transceiver. A raft just isn't practical.
http://www.gps.co.uk/htmfiles/surveqip/fastfind.htm
QDM