A vessel on course 270°T at 12 knots takes a relative bearing of 045° on a charted buoy at 1400. At 1424, the relative bearing to the same buoy is 090°. Applying the doubling-the-angle technique, what is the vessel's distance off the buoy at 1424, and what additional navigational action does Bowditch recommend to manage cumulative error in this running fix?

Question

Accepted Answer

B. Distance off is 4.8 nm; cumulative errors should be checked against fixes whenever possible — At 12 knots for 24 minutes, distance run = 12 × (24/60) = 4.8 nm. Bowditch Ch. 7 §703 states that in the doubling-the-angle technique the distance run equals the distance to the object at the second bearing, so distance off at 1424 is 4.8 nm. However, Bowditch Ch. 23 §2301 states that cumulative errors must be checked against fixes whenever possible, because DR assumptions underlying the technique may introduce error.

Answer

A. Distance off is 4.8 nm; no further action is required because the doubling-the-angle technique eliminates DR error

Answer

C. Distance off is 9.6 nm; cumulative errors should be checked against fixes whenever possible

Answer

D. Distance off is 4.8 nm; the result is a simultaneous fix and requires no further verification

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