"if the trades have been blowing for any amount of time & you are following them you should have a following sea, meaning that your headed in the same direction as the waves (hopefully a long rolling swell)"

Beautiful picture, Barry.

But it reminded me of sailing (dieselling, actually) on the Nella Dan from Melbourne to Mawson, through the raoring forties with their long swells coming at you from 45 degrees off the starboard bow. The rounded nature of the Nell's hull (so it could pop out of pressure ice, lie at 87 degrees from vertical but still recover to float upright) meant the ship had a godawful corkscrewing roll. Measured at 57 dgrees from vertical when I was on it.

Cheers, Rowan