having the chief axis or distinctive part perpendicular to a surface; set or placed in a vertical position, posture, etc.; pointing or directed upwards; not inclined or leaning over
Prior to and during loading or unloading operations the master shall ensure that:
1. the loading or unloading of cargo and the discharge or intake of ballast water is under the control of the ship's officer in charge;
...
3. the ship shall be kept upright or, if a list is required for operational reasons, it shall be kept as small as possible;
