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» Online Classroom   »   » Public Discussion of Inland and Coastal Navigation   » Problem 4-2 and 4-1

   
Author Topic: Problem 4-2 and 4-1
Michael Mitgang


 - posted January 11, 2005 11:20 PM      Profile for Michael Mitgang           Edit/Delete Post 
Why is the answer to 4-2 (D): Bearings should be taken at about 90 degrees apart? My take away from doing 4-1 and 4-2 was that you should use sightings that are closer to where you are rather than further away. Using Trial Island light to find the fix in 4-1 also shows that the error is much smaller (because I am closer to it rather than the light on Discovery Island). It does not appear to have anything to do with being 90 degrees off the range line. Please advise and clarify. Thanks.
From: Menlo Park, CA
David Burch


 - posted January 20, 2005 06:01 PM      Profile for David Burch           Edit/Delete Post 
You are right to raise questions about this one.

It mixes up two issues, the issue of distance off (we should always take the closest objects possible) and relative bearings (we should take targets near perpendicular if possible, or at least avoid targets that are closer than 30° or so.

Usually the closeness factor is more important, as you have pointed out.

At first opportunity, i will remake this problem so that the relative bearing comparisions are done with targets that are about the same distance off. As it is now, the fact that the 4-2 targets are closer than in 4-1 maskes the very result we are trying to illustrate.

thanks for poinint this out.

--david

From: Starpath, Seattle, WA


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