NavList:

I think the reason people defend the 24 in number, 15° wide time zones explanation is because they like the regularity of all time zones having the same width and think that this is its most important aspect, it isn't.

You can choose any time and date you want on your ship as long as you keep track of the conversion factor so that you can determine GMT for navigation purposes. It is only necessary to worry about the date when you make contact with the shore where it is useful to have your calender match those ashore.

There is the old story about the missionary in the south pacific who liked doing Sunday services. He lived on an island just west of the dateline. After doing his Sunday service on his island he got in his boat and sailed east to the next island just east of the dateline and stayed in the hotel there. He then got up he next day, which was Sunday again, and conducted a Sunday service there. He then returned to his home west of the dateline and prepared for the next Sunday. He was happy because he had two Sundays each week.  The rest of the story continues that there was a guy living on the island just east of the dateline who hated Sundays because all the saloons were closed then. So he used the opposite method, he partied hard Saturday night and then boarded the steamer for the missionary's island on the opposite side of the dateline. His ship and the missionary's boat passed each other in the middle of the night. He woke up the next morning in the harbor and went ashore and started drinking again because it was now Monday on that island and the saloons were open. He drank all day and then he boarded the overnight steamer home, again his ship and the missionary's boat passed each other in the middle of the night. He managed to avoid having any Sundays, for him, the saloons were always open.


U.S. Navy Regulation, Article 1031 issued in 1920 required Navy vessels to keep time based on the standard time zones. Paragraphs 6e and 8 however gave the commander the authority to set his clocks in a non-standard way (but he must note in the logbook the exact "hours, minutes and seconds" needed to convert ship's time to GMT as the Z.D. and that also had to be posted next to the ship's clock) when near a shore that kept non-standard time or under circumstances that "may render desirable a departure from the regular method."

This was of interest in the Earhart case. She was aiming for Howland island which is located at 176° 38' west longitude inside the "MIKE" time zone with Z.D. of +12 hours. The Coast Guard cutter Itasca was drifting off shore but kept time with a Z.D. of + 11:30 because is was operationally desirable because it was cruising east and west, crossing the normal dividing line between "L" and "M", Z.D. + 11 and +12. Earhart kept GMT for her radio schedules so her times were offset by thirty minutes from Itasca's time and many think this might have contributed to the breakdown in radio communication schedules (I don't). In the 1930's, standard Hawaiian time used Z.D. of +10:30. There were several Hawaiians on Howland island and they also kept their clocks set to a Z.D. of + 10:30 to facilitate keeping their radio schedules with the stations on Hawaii. This led to the times being kept and entered in the respective radio logs to differ by an hour between the Howland island logs and the Itasca radio logs with the ship drifting just off shore. This has also caused some confusion for Earhart researchers.

In aviation "Zulu" time is the standard everywhere on earth. Your sailboat will take a week to cross a time zone but a plane does it every two hours, or every one hour at high latitudes crossing from Europe to America so there is no way to keep spinning the clock dial to keep up with the changing time zones. This also eliminates any misunderstandings in scheduling flight plans and radio schedules of the type near Howland on July 2, 1937.

gl