Good point. Assuming you survive the ditching (and statistics show that most ditchings are sucessful according to the NTSB), thats when your problems start.
I watched a video on a North Sea survival course of Duncan Goodhew and Sharon whatshername (Olympic swimmers) dumpped in a swimming pool at average UK water temps, and after 10 minutes they were both useless, and they are !!!!! hot swimmers.I can vouch that the costal waters are still bloody cold, even in a 5mm wetsuit, the Channel Light Vessel is showing 10°C at the moment. There are some interesting graphs around showing survival time vs water temp, and its not very long at these temps.
EA