Calling master as per STCW-95

 

bullet If restricted visibility is encountered or expected.
bullet If traffic conditions or movements of other ships are causing concern.
bullet If difficulty is experienced in maintaining course.
bullet On failure to sight land, a navigation mark or obtain soundings by the expected time.
bullet If, unexpectedly, land or a navigation mark is sighted or change in sounding occurs.
bullet On the breakdown of the engines, steering gear, or any essential navigational equipment.
bullet In heavy weather, if in any doubt about the possibility of weather damage.
bullet If the ship meets any hazard to navigation, such as ice or derelicts.
bullet In any other emergency or situation in which the OOW is in any doubt.