It's not really obvious, but this is a dark-morph Trindade (Herald) Petrel making a pass down the boat. The high seas are pretty obvious though.
On this day we had 6 of these birds, a new record for Patteson, and I assume for North America. We had them in both light and dark morphs, as well as intermediate. The short bill and slightly paler belly seperate it from Sooty Shearwater even in this bad view. I think trying to follow these rockets in high winds from a pitching and rolling boat was my hardest challenge yet in photography; quite often I got nothing but water, or a bit of a bird.