Vessel Movement As caused by the action of the waves as the vessel moves through the water.
A vessel at sea may move in six different directions at the same time:
Heave - Rise or fall of the entire vessel.
Surge - Forward or aft movement of the entire vessel.
Sway - Sideways movement of the entire vessel.
Pitch - Rise and fall motion (bow and stern) on the width center axis.
Roll - Side to side (port and starboard) rocking motion on the length center axis.
Yaw - Port and starboard twisting motion on the vertical center axis.