NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Another "emergency navigation" sight reductionmethod
From: Hanno Ix
Date: 2015 Jul 13, 10:21 -0700
re: a little error of cos() scale placement. In fact, I posted a detailed study
on NavList before ascertaining just that!
Actually, I also believe that the mechanical position of the scales may quite well be
within +/- 2 sm when handled correctly during the operations. My guts tell me that
would indeed be the result of some statistical study but we cannot claim it
From: Hanno Ix
Date: 2015 Jul 13, 10:21 -0700
Gary,
I totally agree with your assessment of the sensitivity, or lack of it, re: a little error of cos() scale placement. In fact, I posted a detailed study
on NavList before ascertaining just that!
within +/- 2 sm when handled correctly during the operations. My guts tell me that
would indeed be the result of some statistical study but we cannot claim it
as a fact as of yet as I mentioned before.
But that is not my issue here, Gary!
I am advocating an enhancement of readability here and in my prior postings.
Your scales, as they are now, do not lack accuracy as far as I can see, they
lack somewhat in the "user interface" as it were. With readability I mean the ability
to put the right number to the - probably - right position.
You are working hard to promote the Flat Bygrave, and coming from a
noted practical navigator your arguments carry weight. I think your Flat Bygrave
noted practical navigator your arguments carry weight. I think your Flat Bygrave
would have an easier time to get more generally used if you could polish up
the scales. The addition of 2 arc min dots would be a great help for the user
and are easy to implement.
Please, since the MHR-1 is the standard of Bygrave check out this
point and compare. You will see what I mean.
point and compare. You will see what I mean.
Regards
H
On Mon, Jul 13, 2015 at 8:11 AM, Gary LaPook <NoReply_LaPook@fer3.com> wrote:
In fact, the entire cotan scale from 10 degrees to 80 degrees is marked in ten minutes steps and it doesn't seem to affect the accuracy at all. And look at the cosine scale, part of it is marked in whole degree steps, still no problem. You get a sense when working with it that some things have very little effect on the final answer. Think about using a normal ten inch slide rule to do the sine-cosine computation. Even though some of the inputs might be in the the end of the cosine scale where it is marked only every whole degree it is easy to get results of much greater accuracy.gl
From: Hanno Ix <NoReply_HannoIx@fer3.com>
To: garylapook---.net
Sent: Sunday, July 12, 2015 12:16 PM
Subject: [NavList] Re: Another "emergency navigation" sight reduction method
That actually is a shame. By re-designing the set of marks you are using and including marks for 2 min steps ( e.g round dots ) you could increase the utility of your Flat Bygrave significantly. From my experience with making scales this is not too difficult, there is sufficient space for them.The cot() scale - partially shown in the attached picture - proceeds around 45 deg in steps of 10 arc min. So in this area of the scale any visually interpolation of 2 out of 5 without further reference is rather subjective. And this is the reason of my statement above. It could very well the biggest error component of your design!Gary,your claim of 2 minute or better accuracy is hard to contradict - and equally hard to confirm.It also would make it possible to prove your claim.HOn Sun, Jul 12, 2015 at 6:26 AM, Gary LaPook <NoReply_LaPook@fer3.com> wrote:The cotan scale on my flat Bygrave is only 10 inches long by 7 inches high and I get 2 minute or better accuracy. The cosine scale is smaller. They each fit on standard 8 1/2 by 11 inch paper and clear plastic sheets.gl
