Fly 911 - the Sea King, which is designed to land on the water, is very twitchy especially in roll when afloat - even on a flat calm Canadian lake. The S-92 which isn't designed to land on water would probably be very difficult to keep upright, especially in a 2 metre swell, even with all the flot bags deployed.
Had they made a controlled ditching in those conditions they would probably still have inverted.
I don't completely agree with you here Crab. I agree that the Sea King was (and still is) rather unstable once on the water, and there is quite a bit of first hand experience around to support this. The Puma has also had a fair degree of time on the water, and has shown that it does not always tip immediately. There have been numerous ditching over the years and quite a few have stayed afloat and upright for quite some time - at least several hours before rolling over, and this has not always been in calm seas. The HS Puma ditching in 1996 is the first that springs to mind. A successful ditch, where all got out safely and the aircraft remained afloat and upright, and it was not calm seas.
The lack of a controlled ditching in a 92 makes this all conjecture, but looking purely at the dimensions of the S92 versus the Puma, we know that the 92 has a relatively lower CG, with a considerably wider base, and a longer base along the middle of the cabin. The S92 is 4.7m high from bottom to top of rotor head, and the Puma 4.6m. The fuselage width of the S92 is 3.18m versus the Puma's 2m. If you inclue the tail stab on the 92 it comes out to 5.26m. I acknowledge that is only theory, and that whilst the S92 was not of course designed to "land" on water, it was certainly designed to float. Certainly the Sea State six floats that are installed in many (if not most) machines now, will add a good degree more stability in the roll axis over the SS5 floats. The SS6 floats provide additional floats in the sponsons, to supplement the floats in the nose and under the tail, and should give a good bit of extra time if the landing is controlled. Of course we must train to and be prepared for the worst case, and there can be other factors. The floats may not deploy properly, or the landing may be unstable with lateral movement adding to the vector and a heavy swell will almost always cause the aircraft to roll. That all being said my expectation would be that the S92 would be considerably more stable that the Puma or Sea King (or S61). The difference between the S92 and Puma is felt the very first time you ground taxy, with the 92 very noticeably more stable, with far less tendancy for body-roll.