NavList:

Frank wrote:  "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."

I recall being on a US Navy supply ship a LONG time ago.  Clocks around the ship had signs hung on them like "one hour slow."  I was way to young at that point to understand UT or to determine which time zone the clocks were set to.

But why not keep all timepieces aboard a ship set to UT and simply hang signs noting the offset to local time?   That way resetting the clock every time one crossed into a new time zone would not be required.   And I suspect that setting the clock could cause it to be knocked off displaying accurate time.

I guess what I'm very politely saying is that I'm not sure I agree with Frank's argument -- and, in fact, it would make more sense to keep ship's clock(s) set to UT and simply note the offset to ZT rather than reset the clocks.    So the custom of recording sight times in ZT continues to puzzle me at least -- as I faithfully record sight times in ZT as I have been taught...