# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Compass Error Corection
From: Joe Schultz
Date: 2010 Jun 30, 23:11 -0700

This is a follow-up to Master Chief Franklin's "Compass Error Corection" series of postings of April 2010, last answered by Jeremy in May 2010. If Master Chief has given up on this list (as do most practical navigators) then perhaps our fearless moderator can send this to him privately. His innovation is important to safe, real world navigation.

Master Chief: you're in the wrong place for combining innovation and practical navigation. This list has been taken over by (mostly) dreamers and historians, and you went right over their heads.

You are, in my opinion, applying the old "1 in 60" rule in a very innovative way. Your method is fast and accurate enough for navigation, and needs to be published in the marine professional publications before Navy and merchie leaders will consider making it a standard practice. They, like the dreamers here, believe what they see in print.

My recommendations:
1. Explain in terms of the old "1 in 60" rule, emphasizing the strengths and weaknesses of the approximation.
2. Generate some form of a cookbook solution that ring knockers and trade schoolers can do, even if they don't understand the simple mathematics.
3. Be careful with the numbers you use in your examples, so you don't inadvertently confuse the reader.
4. Write for your audience. The combined underway fix and compass error can't be done by merchies/yachties, for example, unless an athwartship range is shot while steering another range.

Linked is a 13KB file (1_in_60.gif) which is a quickly written idea for you to ponder. I did make a mistake in the Practice Problem: compass system uncertainty and my position uncertainty should be +/- the given numbers.

I remember "1 in 60," in my mind, as "little over big" fractions, then mentally solve for what I need. Distance off, required course correction, or whatever. And now for compass error, thanks to your innovation.

For the dreamers who want to change the conditions to suit a negatively critical argument: there's an old saying from the engineering world. "One good thing about standards - there are many to choose from." Three minute, six minute, and 1 in 60 rules are practical approximations for practical navigation by real-world travelers.

Joe

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