NavList:

Stan K, you wrote:
"Sure, we could do that for our sights, but what about making a phone call to someone in another part of the world and not wanting to wake her in the middle of the night. Aren't time zones useful for this kind of application?"

Absolutely. We wouldn't want to wake Dana in the middle of the night --she might turn into Zuul. Or for another practical case, you're crossing the Pacific to deliver a cargo to a customer in San Francisco, and you need to explain when you will be arriving at pier 17. Naturally, you would want to use zone time, and not just maritime zone time, but the actual civil zone time in use at your destination. The easy way to do this, of course, is to do all your work in UT and then, in the very last step, convert to the zone time of your destination. You just have to remember which way to go: the Sun come from the east, so the time is later east of you since the Sun has already visited there.

But for celestial observations, there is a certain historical insanity at work. To this day, navigators are taught to record their sights in zone time, presumably because time pieces were relatively rare decades ago, and it was difficult (expensive) to have a separate watch or device displaying UT. Or maybe it has been a long-lasting relic of the transition away from local mean time... There's no need for this practice today. We should record all sights in Universal Time. And we should train navigators to record sights in UT. It's more practical in every way that I can think of, and it eliminates an annoying source of error. Unfortunately, licensing exams are over-loaded with trick questions involving time zones and chronometers "reading" twelve hours from UT and so on. Licensing for celestial navigation has preserved obsolete techniques and turned them into exam games --a lazy means of spreading the grading curve-- in much the same way that lunars were used for exam games right up to the beginning of the 20th century, fifty years after they had ceased to be important at sea.

Frank Reed
ReedNavigation.com
Conanicut Island USA