I was told by some bloke who ditched a 206 into sydney harbour, right between the headlands and too far from each, that if you roll the advancing blade (I think) into the water, the resulting massive torque back through the system will spit the gearbox out backwards away from the cockpit.
Well he said it worked anyway. I'm sure someone knows the full story.
I did the 'waterbird' course on the US Sea King- great aircraft to take off again from water if you've got 1 engine left. The ditching at 30kts fwd speed was fun also
with the aircraft coming to a stop in about a length and a half!!