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On 1/19/2024 8:16 PM, NavList Community wrote:
> This ship sails at about 20 knots constantly, which means that we cover
> 1 nautical mile every three minutes.Therefore, when taking sights of
> three stars or planets to get a simultaneous fix, the LOP’s must be
> advanced to adjust the distance covered and ship’s heading.

Another method is to reduce the sights as usual (calculate azimuth and
intercept) but plot them with respect to one dead reckoning position.
That position need not coincide with the time of any sight.

The principle is that if an observation gives, say, azimuth 180 and
intercept 10 miles toward, it indicates the DR is 10 miles too far
north. And that's true at other any time, to the extent that the DR is
an accurate model of observer motion during the interval. So you can
plot a round of sights as if they were simultaneous at some convenient time.

However, your sight reduction method must use the DR position at the
observation time. The method above is not valid with an assumed position
selected to produce an integer latitude and integer hour angle.


How was height of eye determined during the Atlantic crossing?

--
Paul Hirose
sofajpl.com

   

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