jgrossi at bbnplanet.com
Wed Jan 5 20:50:21 UTC 2000
At this point... I think it's probably most important to find
out what happens in reality as we have no idea the verascity
of these reference in regards to the shipping industry. I'm
having dinner with a friend tonight whose in from time at sea,
I'll ask what his vessel does, and get some references... just
to get an idea of what happens in practice.
Boston, Massachusetts, USA
> -----Original Message-----
> From: Oscar van Vlijmen [mailto:o.van.vlijmen at tip.nl]
> Sent: Wednesday, January 05, 2000 3:37 PM
> To: TimeZoneList
> Subject: Timezone boundaries
> This was part of a mail from Oscar van Vlijmen:
> > [...] Theoretical timezones:
> > Take [0;15W), [15;30W),..., [165;180W), [180E;165E),..., [15E;0E)
> > Times in hours from UT. [ means including, ) means not including.
> > 0-15E +1 [...]
> Gwillim Law wrote:
> Minor correction: what I was trying to express was that ships at sea should
> use UTC between 7.5 degrees E and 7.5 degrees W, UTC+1 between 7.5 degrees E
> and 22.5 degrees E, etc.
> Oscar replies:
> Gwillim could be very right. Looking carefully at for instance the
> "standard time zones" map from HM Nautical Almanac Office and the map
> "standard time zones of the world" from the CIA world factbook (both of
> which maps btw are not up to date), then I can see that they reflect the
> situation Gwillim depicts.
> Another flaw in my list was the absence of a UT+0 zone.
> Thanks for all your remarks.
> Here is the new list:
> Theoretical timezones:
> Times in hours from UT.
> [ ] means including, ( ) means not including.
> This rather arbitrary distinction is needed for mathematical reasons, i.e.
> when implementing in a program.
> longitude range time offset
> [7.5W-7.5E) +0
> [7.5E-22.5E) +1
> [22.5E-37.5E) +2
> [37.5E-52.5E) +3
> [52.5E-67.5E) +4
> [67.5E-82.5E) +5
> [82.5E-97.5E) +6
> [97.5E-112.5E) +7
> [112.5E-127.5E) +8
> [127.5E-142.5E) +9
> [142.5E-157.5E) +10
> [157.5E-172.5E) +11
> [172.5E-180E) +12
> (172.5W-180W] -12
> (157.5W-172.5W] -11
> (142.5W-157.5W] -10
> (127.5W-142.5W] -9
> (112.5W-127.5W] -8
> (97.5W-112.5W] -7
> (82.5W-97.5W] -6
> (67.5W-82.5W] -5
> (52.5W-67.5W] -4
> (37.5W-52.5W] -3
> (22.5W-37.5W] -2
> (7.5W-22.5W] -1
> Oscar van Vlijmen
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