Bondu - how long is a piece of string? Presumably you are suggesting the helo has survived the landing and that the rotor blades have stopped - yes? Because if the rotors are still turning, it won't be long before one of them strikes the next swell and all bets are then off.
So assuming the cab is intact and not leaking like a seive and remains upright and not leaning due to Cof G shift/poor irregular inflation of the flot gear etc, are you asking about the steepness gradient from then on in?
Do modern day pilots calculate a steepness gradient for contacting the sea?
Do they care - as the decision to ditch will not be affected by the sea state. The decsion to ditch is one taken by a pilot because they have no choice. They will simply have to accept the steepness of the swell, no???
What are you getting at?