sry for reviving a month old thread....
1. set the 24 triangle dead on the 12 o'clock marker
2. set the green hand to GMT time (minute hand should match your local time)
3. set the hour hand to your local time
4. if you are in your local zone, the hour and minute hand reads local time (1st time zone)
5. if you look at the green hand and minute hand that's GMT (2nd time zone)
6. now you can move the bezel up or down X many clicks to reflect the 3rd time zone. e.g. if you live in EST, london is 5 hrs ahead and if you turn the bezel 8 clicks back the green hand should reflect PST.
I realize this is an old thread previously revived, but I just got a Rolex GMT Master II, and figured out how it is most useful to me - as a frequent time zone traveler. It is a variation of the above, but I haven't seen it described anywhere exactly as I will. So, my changes are marked in red:
1. set the 24 triangle dead on the 12 o'clock marker
2. set the green or red 24 hour hand to GMT time (minute hand should match your local time)
3. set the hour hand to your local time
4. if you are in your local zone, the hour and minute hand reads local time (1st time zone)
4a. move the bezel back or forward the number of clicks that your time zone differs from GMT. For example, if you live in EST (+5), move the bezel 5 clicks clockwise.
5. if you look at the green or red hand and minute hand it will read local time off the bezel.
6. when you go to a new time zone, you change the hour hand, but not the green or red hand. Now, you can read your local time with the watch and your "home" time off the bezel.
7. if you want to follow ANOTHER time zone instead, simply read the GMT offset on a chart and reset the bezel to that offset.
8. AND, if you are in a "half-time-zone" location like Bombay, or Singapore, after adjusting the hour time to 30 minutes before local time, move the minute time forward 30 minutes AND the bezel backwards 1/2 a click so that "home" time and local time are correct!