It's not in motion, it's stuck where we last directed the ship.

He steps up behind him, swaying against Molly's back to follow the gentle swell of the waves beneath them, docked though they are. His chin finds a shoulder as he covers his hands on the pegs. ]

This is portside because of where the wharf is. See how we're docked? And if we went hard to starboard, it would be the other way because we'd be chasing stars to the right where the open sea is.