Sadly I heard much of this on the scanner back at home, as I was getting ready to go afloat this afternoon. The search was called off shortly before we walked out the door.
It was a small motorised dinghy with 3 guys in it that capsized somewhere just the harbour side of the chain ferry.
Whilst it was blowing around a F4, gusting a touch more, certainly in the harbour the water was pretty flat, and even outside the sea state wasn't too different.
So not sure what caused the accident.
Bournemouth Echo has a slightly mroe detailed article here:
http://www.bournemouthecho.co.uk/new...ch_called_off/