On 2 March your 2216 ZT DR position is LAT 21° 20.0' S, LONG 17° 10.0' W. At that time, you observe Saturn bearing 078° psc. The chronometer reads 11h 14m 04s, and the chronometer error is 02m 20s slow. The variation is 4.5° W. What is the deviation of the standard compass?
• Amplitude or azimuth of a celestial body to find compass error • Relationship between true bearing, magnetic bearing, compass bearing, variation, and deviation • Correcting chronometer time and using the Nautical Almanac for GHA and declination
• How do you turn the observed compass bearing of Saturn into a true bearing using sight reduction (or tables/software)? • Once you have the true bearing of Saturn, how do you work step‑by‑step from true to magnetic, and then from magnetic to compass, keeping track of signs for west/east? • How does a chronometer that is slow affect the UT you use for the celestial body’s position, and why does that matter for its computed true bearing?
• Be clear on the order of corrections: Compass ⇄ Magnetic ⇄ True, and where variation and deviation are applied. • Verify the sign convention: Is west variation and west deviation added or subtracted when going from true to compass in your method? • Double‑check that you used the correct UT from the chronometer (including error) before taking GHA and declination, so your calculated azimuth is valid.
No comments yet
Be the first to share your thoughts!