Your vessel is steady on a heading of 160°...

Question 1 of 31048fork_270b6d0e474a4ef3994

Your vessel is steady on a heading of 160° per standard magnetic compass when you sight Southwest Ledge Light and New Haven Outer Channel Range Rear Light in line dead astern. What is the deviation of the compass based on this observation?

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Question 1 of 31048

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🔍 Key Concepts

• Range alignment: when two lights are in line, their charted alignment gives a line of position; “dead astern” tells you the vessel is on the reciprocal of its heading. • True, magnetic, and compass directions: determine the true bearing from the chart, convert it using the stated variation, then compare the resulting magnetic heading with the compass heading to obtain deviation.

💭 Think About

• What true direction does the charted line between Southwest Ledge Light and New Haven Outer Channel Range Rear Light have, and what direction is that line from the vessel when it is dead astern? • After applying the local variation, how does that magnetic direction compare with the stated 160° standard magnetic compass heading? Use the sign convention for east and west deviation.

✅ Before You Answer

• Use the charted lights’ alignment and account for dead astern by taking the reciprocal direction. • Keep variation separate from deviation; the question asks for the compass error attributable to deviation, not the total true-to-compass correction. • Do not carry a fix or course from step 2 or step 4 into this independent sighting problem; rely on the stated heading and chart alignment.