On 21 April your 1542 zone time DR position is LAT 28°54.0'S, LONG 19°07.0'W. At that time, you observe the Sun bearing 299°psc. The chronometer reads 04h 44m 11s, and the chronometer error is 01m 54s fast. The variation is 3°E. What is the deviation of the standard compass?
• Amplitude / azimuth of the Sun to find compass error • Relationship between true bearing, magnetic bearing, and compass bearing (variation and deviation) • Correcting a chronometer time using chronometer error to get correct GMT/UT
• How do you turn a compass bearing of the Sun into a true bearing step by step? Think about which corrections come from the chart and which come from the compass. • Once you get the Sun’s true azimuth, how do you compare it with your compass bearing (psc) to find the total compass error? Which side is East and which is West? • After total compass error is known, how do you separate variation and deviation? What is the sign convention (East or West) when going from true to compass and back?
• Be sure you first correct the chronometer time using the stated error before entering the almanac for GHA and declination. • Confirm the zone description (ZD) you’re using for 1542 zone time so you convert properly to GMT/UT. • When comparing bearings, be careful with 0°–360° wraparound and with the order of applying variation then deviation to go from true → magnetic → compass (or reverse).
No comments yet
Be the first to share your thoughts!