The BHT-222U-FMS-12 says that the emergency flotation should keep the helicopter stable in up to Sea state 6 which is 25 kt wind and waves up 2.5 to 3.4 m height.
I presume that the B-222 is unusally stable compared to many other helicopter types due to the emergency float layout. The main floats are positioned outboard on the stub wings under the wing end cover.
