Master is overall in-charge of the ship and he is responsible for everything on-board, So in difficult situations its Important that the master comes to bridge or wherever needed. We know that 3rd officer 2nd officer and a chief officer can keep watch as they have a Certificate of competency (COC), in case if the chief officer is more in age or more experienced at sea But then also the captain is considered the in charge and The officer on watch should call the ship’s master in the following situations-

1. Danger to the ship because of traffic or movement of other ships
2. Difficulty in maintaining a proper course
3. Danger to ship or ship’s stability because of heavy weather.
4. Malfunctioning of alarms or signaling equipment.
5. On encountering restricted visibility.
6. Breakdown of the propulsion system, steering gear, or machinery
7. Malfunctioning of radio equipment.
8. During maneuvering in piracy areas
9. On sighting land or navigation mark that can turn out to be dangerous
10. Breakdown of essential navigational equipment
11. On encountering navigational hazards such as rocks, icebergs, or shipwrecks
12. Failure to sight land or navigation mark that should have appeared.
13. Sudden change in sounding or readings at an inappropriate time
14. On receiving some emergency or important message from nearby port or ship
15. If you face suspicious floating object in piracy affected area