Goodaye,
Oh dear. Huge rolling seas again... I hope the sea is not like that in every battle.
I'm a professional seafarer who has spent over 20 years sailing the oceanic zones covered by the game.
From all the screen shots I've seen they have got the sea states down pretty well. The 'Huge rolling seas' are very typical ocean swell patterns and not out of the ordinary at all. Nor are their dimensions which you can judge from the ship models.
I've sailed square riggers (replicas) across oceans and judging by the video's I've seen (particularly the recent developers one focusing on the sea battles) the motion of the ships through the ocean is an accurate representation (given the limitations of graphics and computers - ships move in six seperate degrees of freedom) of reality.
Big provisio is that these comments are based on screenshots and one limited video but full marks so far.
On a related matter, sailing a square rigged ship directly into the wind (I've got the impression that this was a function of the 'waypoint system') was a non-event (couldn't be done with the technology of the day and you'd likely de-mast in a stiff breeze) but the game isn't positioning itself as the end-all and be-all of realism so that's not something I'm losing sleep over.
Cheers,
Lancer