Excellent tip. sitting aft of the centre better for updown motion
I would add if you are sitting down below on the public ferry
From SXM to AXA sit on the port side with the window cracked open for ventalation - port is left facing forward. The starboard side often has the ports closed due to spray - so no air flow and a little stuffy for anypne with motion issues
From AXA to SXM, the reverse, sit on the starboard side [right facing forward] - same logic

Cheers
J&B