They need to fit water pockets (or a disconnect) to that parachute. I'll bet that aircraft was dragged at some speed (leaving its occupants behind in the water), luckily they were in the solent so every wind direction was 'on-shore'. I had something similar happen during a RIB airdrop test when one of the parachutes didn't disconnect, capsizing the RIB and towing it towards America (from the Welsh coast) faster than the range tender could sail.