As you pass between trestle "B" and trestle "C" of the Chesapeake Bay Bridge - Tunnel, you sight along the trestle "C" when it is in line. The trestle bears 057° per standard magnetic compass while the vessel is heading 320°T. Which of the following can be determined from this information?
• Standard magnetic compass vs. gyro/true heading and what each reference means • How compass error is defined: CE = True bearing - Compass bearing (or variation + deviation) • Whether you can determine deviation from a single comparison when you do NOT know variation or true bearing of the object
• Is the heading of 320°T given in true or compass? What does the phrase standard magnetic compass tell you about the 057° reading? • To calculate deviation, what two pieces of information must you know? Do you have both in this problem? • If the information you have is not sufficient to calculate an actual error, what kind of conclusion can you reasonably make about your deviation table or your compass?
• Identify clearly which angle is true and which is compass in the problem statement • Ask yourself if the true bearing of the trestle is provided anywhere (or if you could logically infer it) • Decide whether a single observed bearing on one heading is enough to prove a numerical deviation value like 10°W or 12°W
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