The time error would show the adjustment needed to the
ship's clock to synchronize it with the precise atomic clocks on three transmitters.
"After inheriting his
ship's clock, Roger became fascinated by maritime history and the associated memorabilia.
If a
ship's clock was out by just one minute it would mean a difference of 60 miles in the true position of the ship.
Around midday the crew would shoot the Sun with sextants, determine local noon, and adjust the
ship's clock accordingly to provide ship's time.
And as the
ship's clocks had gradually moved forward to catch up with British time, we didn't even have jet-lag.
By dinner's end we are well into evening, and it is later than we think: The
ship's clocks have been set forward an hour upon leaving New York.
And as the
ship's clocks had gradually moved forward to catch up with Irish time, we didn't even have jet-lag.
The abundant evidence from primary sources allows us to conclude that on the evening of July 29, 1945, both the Indianapolis and the I-58 were observing the east longitude date convention, but with the submarine's clocks set 9 hours ahead of Greenwich, and the
ship's clocks adjusted to a noninteger value 912 hours ahead of Greenwich.