Documenting Chronometer Error
Information concerning each chronometer (error, successive daily rate, and
average daily rate) must be recorded in the Navigational Timepiece Rate
Book, NAVSEA 4270. (See fig. 5-6.) Each page of NAVSEA 4270 can
accommodate the records of a maximum of three chronometers for 1
How to Check
Use the following table to check and record chronometer error. You will
need pencil, paper, and a comparing stopwatch handy.
Obtain a time tick signal from the communications center.
Determine from the time tick the next minute that will be
sounded; write this value down. When the signal is sounded,
start the comparing watch.
At the exact moment the comparing watch marks on the minute,
note the exact time for chronometer 1. Write down the time for
Compare the two time values and determine the difference of
time. It is always preferable to change the larger time value to
ease addition or subtraction. In our example, the comparing
watch time is the larger value and equals 1 lh 15m 00s. This
converts to 11h 14m 60s.
llh 14m 60s GMT
- llh 14m 43s GMT
Record results in the Timepiece Rate Book, compare the results
with the previous day and compute the difference, assign
a - value if the chronometer is slower; assign a + value if the
chronometer is faster.
Repeat steps l-5 for the remaining chronometers, replacing
chronometer 1 with the chronometer you are comparing.
At the time of publishing of this TRAMAN, the use of GPS time as the
single source reference for setting ships time has not been approved.
However, the use of GPS time signals may be approved in the near future.
Check with your Type Commander Staff Navigator for guidance on this