On May 20 your 2300, (ZD +4), DR position is...

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Question 1 of 2066636eea28f7522a1c51b3b1

On May 20 your 2300, (ZD +4), DR position is LAT 42° 07' N, LONG 81° 02' W. At that time, you observe Polaris bearing 012° psc. The chronometer time of the observation is 03h 02m 23s, and the chronometer is 1m 17s fast. The variation is 9.5° W. What is the deviation of the magnetic compass?

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Question 1 of 20

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🔍 Key Concepts

• Using a Polaris azimuth to find true bearing and compare with compass bearing • The sequence: psc → psc (corrected) → compass → magnetic → true using deviation and variation • How chronometer correction and ZD help you get the correct Local Hour Angle (LHA) of Aries for Polaris tables

💭 Think About

• How do you turn the chronometer reading into the correct GMT of the observation, given that the chronometer is fast? • Once you know the correct time, how do you get the LHA Aries and then the true azimuth of Polaris from the tables for the given latitude and LHA? • After you have the true azimuth of Polaris, how do you compare it step‑by‑step with the psc bearing (012° psc), given that you already know the variation 9.5° W, to isolate the deviation?

✅ Before You Answer

• Be sure you correctly apply the chronometer correction (fast vs slow) when finding GMT. • Confirm you are using the correct Polaris azimuth table entries for your latitude (42° N) and the computed LHA, not just the nearest whole hour if the table uses interpolation. • When converting bearings, carefully track the signs: West variation is "West is Best" (add to true to get magnetic) and then compare magnetic vs compass to get deviation (East is least, West is best).

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