Which of the following is not shown on the main VMS screen?

The main VMS (Voyage Management System) screen typically provides essential navigational data to the users, helping them to make informed decisions while at sea. Out of the listed options, SMG (Ship Management Group) is not a fundamental navigational function displayed on the VMS screen.

NAV relates to navigation data such as heading, speed, and course, which are crucial for the safe operation of a vessel. Radar is displayed to provide situational awareness by detecting other vessels and obstacles in proximity. Charts are integral as they offer graphical representations of waterways, helping the navigator to chart a safe course.

However, SMG primarily refers to the management or operational aspects of the vessel rather than the navigational support directly relevant to the VMS. This distinction highlights why SMG is not included on the main VMS screen, as it does not directly pertain to the navigation or voyage management functions critical for operating a vessel safely.