Nearly there James, the sea in the Bay can be smooth like a millpond, but it is never still, sea rollers building up from 2000+ miles from the Atlantic when they reach the Bay have nowhere to go and rebound off the Continental Shelf and the rocky coast prevalent in the Bay causing an underlying swell to rebound seawards under the surface, so although the surface is smooth you will always roll when crossing the Bay. The short sharp seas experienced are caused by strong westerly winds combined with the influx of Atlantic rollers increase that rebound effect, much like the short sharp seas in the North Sea which is surrounded by land in fairly close proximity. The Western approaches have different sea conditions to the Bay because the Atlantic rollers can dissipate by escape channels such as the English Channel, Celtic Sea and the Northern approaches so you will not experience the same conditions as in the Bay, where many ships depending on their length cannot find their rhythm and tend to pound more when fully loaded. Going across the Bay is always a surprise, one crossing blissful with a slow gentle roll and another time like a submarine. But we loved it!