NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Resetting clocks on big ships
From: Russell Sher
Date: 2000 Jul 20, 1:36 AM
From: Russell Sher
Date: 2000 Jul 20, 1:36 AM
Last year we travelled to St. Helena Island from Cape Town on the RMS St. Helena. An interesting point about changing of the ship's clocks is that the noon-to-noon run and resulting average speed is calculated from 1200 to 1200, ignoring any changes to the clock as time zones are crossed. i.e. the noon-to-noon run may be 23 hours or 25 hours on certain days, depending upon which direction the vessel is travelling. Even at the start of the voyage which began at about 1600 local time, the first noon-to-noon position and average speed announcement was based upon 20 hours. (so that the average speed didn't figure against the distance covered, until one realised that it was calculated by dividing the distance by 20 not 24).
