The world is divided into 24 time zones, each 15º wide. The middle of 0 zone goes through the Greenwich meridian, so it is also called Greenwich Mean Time (GMT) or, officially, Co-ordinated Universal Time (UTC). From this zone there are zones numbered from +1 to +12 eastward of UTC and from -1 to -12 westward. The line between +12 and -12 is the International Date Line. Some countries do not strictly follow this recommended system and have their own time zone (e.g., India has the time zone +5h 30 min, while Nepal has 5h 45 min). Many countries use daylight savings time beginning in Spring.
Each ship has her own local time. Usually it is the same as the time in the country where the ship is, but when the ship sails between ports with different time zone, the master decides the current local time. The radiotelephone operators must be conversant with Co-ordinated Universal Time (UTC), which was formerly known as (GMT). In most cases even in local communications it is preferable to use UTC, which in expression may be abbreviated by substituting Z for UTC; e.g., “ONE FOUR FOUR SIX ZULU”, for 1446 UTC.
Only strictly local transmissions of local import should use local time, and each presentation of a time should be followed by the full expression “local time”. For example, 1:46 p.m. local time would be expressed as 1346, “ONE THREE FOUR SIX: local time”.
Each ship has her own local time. Usually it is the same as the time in the country where the ship is, but when the ship sails between ports with different time zone, the master decides the current local time. The radiotelephone operators must be conversant with Co-ordinated Universal Time (UTC), which was formerly known as (GMT). In most cases even in local communications it is preferable to use UTC, which in expression may be abbreviated by substituting Z for UTC; e.g., “ONE FOUR FOUR SIX ZULU”, for 1446 UTC.
Only strictly local transmissions of local import should use local time, and each presentation of a time should be followed by the full expression “local time”. For example, 1:46 p.m. local time would be expressed as 1346, “ONE THREE FOUR SIX: local time”.