A vessel is on course 090°T at 10 knots. At 1000, a lighthouse bears 045°T (relative bearing 315°). At 1030, the same lighthouse bears 090°T (relative bearing 000°, dead ahead). The navigator advances the 1000 LOP along the DR track to 1030 and intersects it with the 1030 LOP. Which statement best characterizes the result and its reliability?

Question

Accepted Answer

B. The result is a running fix, less accurate than a simultaneous fix, because the advanced LOP carries forward DR assumptions — Bowditch Ch. 7 §702 defines this procedure as a running fix and states it is less accurate than a fix from simultaneous LOPs because the advanced LOP depends on DR assumptions. Bowditch Ch. 23 §2301 reinforces that errors accumulate when the vessel is assumed to have held the planned course. The bearing did not double (it changed from 315° to 000° relative, a 45° change, not a doubling), so the doubling-the-angle criterion of §703 does not apply here.

Answer

A. The result is a fix of the highest accuracy because two simultaneous LOPs were used

Answer

C. The result is a running fix of high accuracy because the bearing changed by 45°, satisfying the doubling-the-angle criterion

Answer

D. The result is not a valid running fix because the same object was used for both observations

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