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    Re: Time zone confusion
    From: Gary LaPook
    Date: 2011 Oct 25, 14:53 -0700
    U.S. Navy Regulation, Article 1031 issued in 1920 required Navy vessels to keep time based on the standard time zones. The standard correction factors for converting one time to another used by navigators and, by regulation, the Navy is to use the sign that will convert local time to Zulu time, this is called the "Zone Description" (Z.D.) and must be recorded in the log book and next to the clocks.

    So I suggest that anybody doing Celnav stick to this convention to avoid confusion if trying to use one convention in one situation and another convention in a different situation.


    --- On Tue, 10/25/11, Apache Runner <apacherunner@gmail.com> wrote:

    From: Apache Runner <apacherunner@gmail.com>
    Subject: [NavList] Re: Time zone confusion
    To: NavList@fer3.com
    Date: Tuesday, October 25, 2011, 11:57 AM

    Paul - 

    OK, I think I understand what's going on - but someone can chime in.

    Nautical time is a standardization for ships clocks for things like log-book entries.   It follows an 'ideal' pattern of the 15 degree separation of the center of zones when at sea, although uses local time, e.g. if in port.   The logbook entries have to state, however, the relation of the time reference to UTC for clarity.  The standard for these is to state the number you add to the clock time as reported in the logbook to get UTC.   Hence, zones east of the PM, you would subtract the number (it appears as negative) and zones west of the PM you would add the number (it appears as positive).

    For international time standard reporting, it's the opposite in the sense that the zone is quoted as the operation you make to UTC to obtain the local time, so positions to the east of the PM you add the number (it appears as positive) and positions west of the PM you subtract the number (it appears as negative).

    So, I think it's just a matter of convention.

    John H. 

    On Tue, Oct 25, 2011 at 2:13 PM, Paul Werner <paul.werner@comhem.se> wrote:

    Sorry. I quoted Tim Bartlett's explanation shorter than it is.
    According to him zones ahead of UT are generally those to the east and zones behind UT those generally to the west.
    (Would have been better with a scan after all.)

    Paul Werner
    N59 E18
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