Question 1 of 2921866636eea28f7522a1c51ae42

On 7 December your vessel's 0835 zone time DR position is LAT 28° 30.0' N, LONG 125° 39.3' W, when an azimuth of the Sun is observed. The chronometer time of the sight is 04h 34m 48s, and the Sun is bearing 113° per standard magnetic compass. The chronometer error is 01m 24s slow, and the variation in the area is 13.0° E. What is the deviation of the standard magnetic compass?

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Question 1 of 29218
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On 7 December your vessel's 0835 zone time DR position is LAT 28° 30.0' N, LONG 125° 39.3' W, when an azimuth of the Sun is observed. The chronometer time of the sight is 04h 34m 48s, and the Sun is bearing 113° per standard magnetic compass. The chronometer error is 01m 24s slow, and the variation in the area is 13.0° E. What is the deviation of the standard magnetic compass?

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🔍 Key Concepts

• Azimuth of the Sun for determining compass error and deviation • Relationship between true bearing, variation, deviation, and compass error (TVMDC or CDMVT ladder) • Conversion between chronometer time, GMT/UT, LMT, and zone time to find correct GHA and declination

💭 Think About

• How do you get from the observed standard magnetic compass bearing of the Sun to a true bearing using the vessel’s position and the correct time of sight? • Once you have a true azimuth of the Sun, how do you compare it with the observed compass bearing to find total compass error, and then separate variation from deviation? • In the TVMDC (or CDMVT) sequence, in which direction do you apply east and west corrections when moving from true to compass and from compass to true?

✅ Before You Answer

• Be sure the chronometer error is applied with the correct sign (slow vs fast) before entering sight reduction tables or almanac data. • Confirm that you are using the correct zone description and sign for converting zone time to GMT/UT. • After finding the azimuth, carefully check whether your computed compass error is east or west, then subtract the known variation (13.0° E) to get deviation and its direction.