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» Online Classroom   » Celestial Navigation   » Public Discussion of Cel Nav   » CelNav book - exercise 4.3 - parallel ruler?

Author Topic: CelNav book - exercise 4.3 - parallel ruler?
John Pinto

 - posted May 14, 2021 11:01 AM      Profile for John Pinto           Edit/Delete Post 
The instructions for exercise 4.3 says to use only dividers and the scale on the sheet. But shouldn’t we also be using a parallel ruler or protractor for some of the examples? Especially #6 to determine bearings?

Also what’s an acceptable error when doing these exercises off the printable PDF of the figure? For #5 the difference I get from the answers is 0.5 nm for A and B and 1.0 nm for C and D. That seems to be inherent in using a PDF printout as you are going to get more distortion the greater the distance you are measuring.

From: Orlando
David Burch

 - posted May 14, 2021 12:08 PM      Profile for David Burch           Edit/Delete Post 
The note you refer to applies to the first 5 exercises. The 6th one is a different type of measurement that uses parallel rulers or a rolling plotter. Any of them might benefit from the use of a straight edge, but not strictly required, and a pencil.

We have notes on using plotting tools here:


We have notes on answers here:


From: Starpath, Seattle, WA

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