Jacob & co replica Watches Setting the Rolex GMT M

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Setting the Rolex GMT Master II
Rolex "GMT Master" watches have been around since the late 1950s.
Steady incremental improvements have been added over time, and this
watch has even been to the moon! It is very popular among
professional soldiers and commercial airline pilots. It is my opinion
that this is the coolest (mass-produced) Rolex ever made, because it
has four hands, and not just the usual three, along with a
bezel dial that you can rotate! In other words, there are five things
that you can play with when you set this watch:

Let us label everything as follows:
S---the second hand.
M---the minute hand.
H---the twelve-hour hand (the typical "hour" hand).
T---the (red) twenty-four-hour hand.
B---the bezel.
Everybody knows how to set a regular watch, with S, M and H. But T
and B confuse nearly everybody. The factory manual that I read
(perhaps there are newer revisions?) does not describe the correct
convention to set T and B. In fact, the manual is very vague and
leaves everything up to the taste of the reader. Indeed, every single
person that I have seen wearing one to date has missed the point of
how it should be set,[link widoczny dla zalogowanych], as hard as that is to believe, and I fear that
they're wearing it for petty cosmetic reasons, as gaudy jewelry, and
not because they grasp its great utility. (But who am I to question
the pursuit of cosmetic excess? :)

A small amount of thought reveals that there is only one correct
convention to set this watch. Under this convention, you can look at
this watch's face and immediately report the following (click the
image to enlarge):

It is 18:54:09 (6:54:09pm) in my time zone. I am currently seven
hours behind GMT---this means that I am either in Arizona, California
during the summer, or parts of Mexico. (I'm actually in California,
so it is 18:54:09PDT.) It is 01:54:09GMT.

Then, if you asked me what time it was in Tokyo, for example,[link widoczny dla zalogowanych], I'd
know that it is (probably) 10:54:09 (10:54:09am). Greece? (Probably)
03:54:09 (3:54:09am). This kind of calculation is very easy, but you
have to set your watch properly, and understand a few simple facts,
outlined below.
GMT, Standard Time, and Daylight Savings Time
Before turning to issues specific to the watch, it is important to
understand the idea behind GMT, or "Greenwich Mean Time." Greenwich
is in England. (We really want "Universal Time" [UT], but for our
purposes it is the same as GMT.) GMT is an international concept, and
the watch was named after it.

GMT is the same everywhere in the world; it does not depend on your
location. If you ask any two people what GMT is, at the same moment,
they should give you the identical answer. GMT does not change over
time zones, and it does not have "daylight savings time" (DST)
corrections, etc.

Once you know what GMT is, you can figure out the "standard time"
for a specific country (or portion thereof, in some cases) of
interest. Once you know the "standard time" in said country, you can
take "daylight savings time" (DST) into account, if needed (should it
be summer), and finally get the correct local time, i.e., the time
that a native would report if asked in the street.

So here is the recipe: GMT --> standard time --> local time (includes
DST corrections).

To determine the standard time, you add to GMT as follows, where the
integers represent hours:
CityStandard Time = GMT +Local Summer DST Offset
Hawaii-10None
Los Angeles-8+1
Mexico City-6+1
New York City-5+1
Buenos Aires-3None
*LONDON*01
Paris+1+2
Rome+1+2
Athens+21
Moscow+3??
Baghdad+3+3
Tehran+3.5None
Bombay+5.5None
Taipei+8None
Tokyo+9None
Sydney+10None
WARNING---There are undoubtedly mistakes here, so be careful to
lean the answers for your favorite countries.

There are some excellent resources on the Internet that give more
cities, where some are mentioned in the reference section of this document, and I also
have an extended version of the above
table.

It is evident that you can make good guesses if you think about
geography for a few minutes, but you need to be a lawyer to be sure.
(Consult a good map if you're curious; the lines for the time zones
make all kinds of crazy twists.)

Adjusting for daylight savings time is a bit of a problem. If the
country is around the equator, don't add anything. If the country is
enjoying summer, add zero or +1 hour in most cases. Note that summer
in the northern hemisphere is winter in the southern hemisphere, and
the converse holds; so when it is winter in South Africa it should be
summer in Greece.
Example: Los Angeles, Greece and South Africa
The local time in Los Angeles is GMT+(-8) in the winter (i.e.,
"Pacific Standard Time"), or GMT+(-7) in the summer (we add +1 for
DST, to get "Pacific Daylight Time"). Summer in Greece is the same as
summer in California, as they're in the same (northern) hemisphere, so
the time in Greece should be about GMT+2+1, or GMT+3. South Africa is
probably stuck in winter at this time, so they probably use standard
time, so it is probably just GMT+2.
Interpreting the GMT Master's Face
The watch's movement drives S, M, H, and T, but only you can move
B. In the following figure, S = 09, M = 54, H = 6; that's clear.
What about T? Read T against B. T seems to be something like T=18.9.
So it is nearly 19:00:00, but not just yet! We stick in the values
for M and S, so it is 18:54:09 in our time zone (nearly 19:00:00).

But what time zone are we in? You also can note that B's
triangular marker is seven steps to the right (clockwise), so B=-7.
If the marker is turned to the left (counter-clockwise), B>0. B=-7
suggests Arizona in the winter, California in the summer, etc.

As the picture was taken in California in the (local) summer,
adding +1 to the time is probably going to be correct, at least for
locations in the northern hemisphere. I know that South Africa is
GMT+2 (standard time), and it is winter there,[link widoczny dla zalogowanych], so we're GMT+2, or
(2+01):54:09, or 03:54:09. Greece is GMT+2 for standard time, and
they probably add an hour in the summer, making it (2+1+01):54:09, or
04:54:09.

It is hard to remember countries that add an extra half-an-hour, and
exactly when places start DST, but at least you'll be close.

You can figure out the M and S in GMT from reading the hands. You
could move B=0 and read the time directly from T, M and S. But to
understand the hour, there is an easy shortcut: read the T hand on
the inside dial using the hour markers for H (it reads about 0.9),
double that (1.8), round down to the lowest integer (1), and you have
the hour. So it is 01:M:S, or 01:54:09. In other words, you don't
have to change B to figure out the time in GMT, you can do it
instantly.
Setting the GMT Master II
The winding stem has four positions.
Position 0: Crown screwed down (default position). Position 1: Crown unscrewed and just free of the screw threads
(for hand-winding). Position 2: Crown pulled to first notch (makes the H hand move by
+/- 1 hour; this does not impact S, M or B.) Position 3: Crown pulled to second notch (the watch stops, and you
can advance M [with H and T hands] as you see fit). How to set B
You don't have to touch the stem to play with the bezel. If your
local time zone is negative (you're west of Greenwich), rotate B
clockwise by the correct number of hours. If your local time zone is
positive (you're east of Greenwich), rotate B counterclockwise by the
correct number of hours. If done correctly, T, when read against B,
shows the twenty-four hour time in your time zone.
How to set H
When you travel somewhere, set B to the correct time zone. To
change H, select position two, and adjust H until the hour is correct
(in +/- one hour increments). Note that M, S and T will continue to
turn,[link widoczny dla zalogowanych], so your watch will not lose time! Restore position zero when
finished.
How to set T and M (and Stop S)
Move B so the arrow is above the crown (B=0). Select position
three and adjust T to give the 24h time in GMT, where T is read
against B's scale. You'll note that M moves when you rotate the stem,
but S stays fixed. (S and M run at every position except three.)
When done, restore position zero.

If you don't know what time it is in GMT, ask the United States
Navy, a Global Positioning System (GPS) unit, etc. For our
purposes, GMT is the same as Universal Time,[link widoczny dla zalogowanych], although there are minor
differences outside the scope of this article. (Select position three
and turn the stem until you get the correct time.)

Once you set T, you will never have to change it again, except to
adjust for error in the watch---T does not change with daylight
savings time, for example.
If the watch stops for a few hours?
In the event that the watch stops for a few hours, pull the stem
all the way out (Position 3) and turn the M, H and T hands around
until the correct time is reestablished. If you should jump the hour
hand forward (Position 2), then T will be set incorrectly.
How does one skip the date forward?
Put the GMT Master II in Position 2 and it is easy to skip forward
as many days as necessary, one hour at a time. Roughly every other
month one has to skip forward a few days because the watch does not
adjust for months shorter than 31 days, but this is an extremely quick
adjustment.
What if you have a GMT Master I?
This does not have the jump-adjustable hour hand, and I'm not sure
as to how one sets it in detail. However, T and B somehow be set to
the correct convention, so everything should be fine.
The Seiko SLT009P and SUZ005P

I am pleased to report that Seiko seems to have made a GMT Master
II clone, the SLT009P (above). This Seiko seems to be relatively
inexpensive and extremely accurate (20s/year), so it might be worthy
of consideration!
Further Reading
See The United States Naval
Observatory and Markus Kuhn's
summary on date and time notation for some excellent references.
You should also employ a search engine; looking for "time standards"
or "time zones."

iSBiSTER sells some
nice time-zone software for PCs running Windows.

An entertaining book on the history of Rolex is The Best of Time,
ROLEX Wristwatches, An Unauthorized History, by James Dowling and
Jeffrey Hess (ISBN 0-7643-0011-3.)

Don't forget Rolex's web
site.

Kleanthes Koniaris, email.