Vessels sometimes move in mysterious ways... so we need a way to describe that motion.
First, think of three axis through the ship. All motion happens along or around these axis. Think of each axis as a pole,
and motion either rides up and down the pole or slides around it.
FYE: when a ship is said to move bodily, the whole ship maintains current list, trim, and heading, but moves in a steady
direction without rotating at all.
The first axis is the vertical.
-Heaving: when a ship moves vertically up and down bodily
-Yawing: when a ship rotates about the vertical axis (when the vessel turns)
The second axis is the longitudinal, running from the bow to the stern:
-Surging: when a ship moves bodily along the longitudinal axis fore or aft
-Rolling: when a ship rotates about the longitudinal axis (the ship lists to one side or the other)
The last axis is the transverse, running from the port side to starboard:
-Sway: when a ship moves bodily along the transverse axis from side to side
-Pitch: when the ship rotates about the transverse axis, (the bow or stern rises while the other end
does the opposite)