On 15 August your vessel is enroute from Bombay, India, to San Francisco, CA. You are steering course 020° T and making a speed of 20.0 knots. Your 1830 zone time DR is LAT 26° 13.0' N, LONG 135° 18.0' W. You observed 3 celestial bodies. Determine the latitude and longitude of your 1935 running fix. ZONE BODY's BODY's OBSERVED STAR TIME GHA DECLINATION ALTITUDE (Ho) -------------------- ------- --------------- --------------- ----------- Spica 1848 180° 24.3' S 11° 03.8' 32° 21.4' Altair 1910 89° 29.8' N 8° 49.3' 43° 06.3' Kochab 1935 170° 33.4' N 74° 14.3' 39° 12.0'
• Running fix using multiple celestial LOPs (lines of position) at different times • Converting zone time to GMT (UT) and advancing the DR position between sights using course and speed • How a latitude/longitude position is found from the intersection of the advanced LOPs and the final sight
• How will your DR position change between 1830 and each of the three observation times, given the vessel’s course 020° T and speed 20.0 knots? • What steps do you take to convert the zone times of each sight into GMT (UT) so you can get the correct GHA and declination for each body? • Once you have three LOPs (from Spica, Altair, and Kochab), how do you advance or retire them to a common time to obtain a running fix?
• Double-check your time conversions: zone time to UT and whether any date change occurs while crossing longitudes. • Verify your run between sights: distance = speed × time and ensure you apply the run along course 020° T correctly in both latitude and longitude. • Confirm that your chosen running-fix position is consistent with the DR track (it should not be unrealistically far from the 1830 DR position along 020° T at 20 knots).
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