Roll is the tilting rotation of a vessel about its longitudinal/X (front-back or bow-stern) axis. An offset or deviation from normal on this axis is referred to as list or heel. Heel refers to an offset that is intentional or expected, as caused by wind pressure on sails, turning, or other crew actions. List normally refers to an unintentional or unexpected offset, as caused by flooding, battle damage, shifting cargo, etc. The rolling motion towards a steady state (or list) angle due to the ship's own weight distribution is referred in marine engineering as heel. - https://en.wikipedia.org/wiki/Ship_motions

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Note added at 5 hrs (2017-08-27 00:30:49 GMT)
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Roll stabilization inside the hull. - http://www.oceannavigator.com/May-June-2008/Roll-stabilizati...

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An inertial navigation system (INS) is a navigation aid that uses a computer, motion sensors (accelerometers) and rotation sensors (gyroscopes) to continuously calculate via dead reckoning the position, orientation, and velocity (direction and speed of movement) of a moving object without the need for external references - https://en.wikipedia.org/wiki/Inertial_navigation_system