From: Mark Coady
Date: 2016 Sep 19, 20:35 -0700
I must say I would like to consider this carefully. Sir I promise I do not lack interest, as each item presented gives me new learning, be it counter or in line to my present primitive thinking. I need to consider each statement over several days to process. I am a methodical thinker and take time to absorb.
I am new enough to wish to debate things carefully in which to learn without embarassing myself with public ignorance. I do understand, from reading many posts on this list over time, that one mans passion is another's poison. Some of us come from a the bent of operating a small vessel (or aircraft) with classical tools, wanting to utilize a combination of modern and traditional methods to enable us to solve with simple methods any box we might find ourselves within classical real world navigation.
That personally is where I started. How to get from point A to point B. I concede and even embrace the use of compact and reliable modern tools such as solar calculators and modern timepieces (and especially real world backup GPS units), but pursued an understanding and ability to work without them using HO 208, 229, 249, log tables, etc. I particularly enjoyed Frank's 19th century celestial.
My understanding is that classical luners are most essentially limited by the accuracy of the sextant itself, and the magnification we ourselves can hold as an observer on a moving vessel.
I cannot argue yet the exact computational accuracy differences in using sextant measures vs center based difference. I need time to understand the deeper differences as you step outside my expertise. With modern computational power diverted to either, I expect they can become far more accurate than the observer can achieve with his frail eyes and hardware. I suppose you can go to great ends to compute your arc error on your sextant at each angle as well. Using rules such as keeping your sights between 45 and 110 degrees helps based on my readings and results.
I guess as a more primitive soul, I look at lunars as follows:
1. A method to practice my sextant sights when horizons are difficult, or simply because they are such a test of accuracy because of the rate of change vs the traditional sun sights. Simply put, I use it as a test of my sextant skill. Traditional computation and accuracy seem good enough when I can do it sitting at an outdoor bar at Block Island. I suspect what is in my glass and my sextant handling ability has a greater effect on my accuracy than modern computational deviations. I am being a bit flip, I realize, but not out of disrespect....more because I am just trying to say I am doing it for fun and practice, and I tend to do that with realistic and traditional expectations of accuracy.
2. Just in case: As a method to truly regain a sense of time should I manage to lose it at sea. If I still have my modern computational power, I surely have the time. I lived through a little sailing disaster back in the early 80's where lost time was a real threat. We ended up under sail with no electrical capbability whatsoever but a few flashlights and a couple of not so perfect watches. The main electrical system was much worse than the original recipe....it was extra-crispied, batteries and all. With modern portable long life electronics, the risk of a repeat experience is minimal, if care in selection of backups (and storing some in the liferaft) is used. If the liferaft is the only thing you expect to have left, I want good handheld electronics and stuff with it. Liferafts in my experience are often notoriously poorly packed by manufacturers and the service folks for protection of things you want truly dry.... like flares..and GPS's.
3. I add that multiple lunars over several hours are an excellent way to accurize lunars, and also prove that we have repeatability that confirms data. Good navigators hate single inputs as they risk unconfirmed errors.
4. I also suppose that as I practice my Lunars, software that supports my efforts to work and understand traditional computation that I can do without computer-only power feels more user friendly and practical to me. It helps me prove my traditional methods, how I could rescue myself with them, and gives easy enjoyable confirmation of my work. I like checking my traditional work with a computer that avoids my dumb math mistakes. I like my answer to actually match, so I know I did it right.
I am not disputing there are reasons for understanding and working with super detailed computational models, but in the real world of practical navigation hence a "nav list", there is also a reason to accept the statistical deviations that are part of the normal navigators life and test ourselves within it, because that is what we might actually do when the computer is down or unavailable.
I guess what I am saying is that there is an equal place for those of us who view navigation as a down to earth practical art for the common man or an art of historical curiosity, vs an esoteric supremely detailed astronomical computational excercise.
This isn't a rebuttal or trying "shoot anything down", just the thoughts of a simpler man who approaches the subject with a different flavor. The differences amongst us keep it interesting, and me for one thinking.
Indeed I owe your thoughts time and analysis to fully digest them. I expect at the very least, embrace them or not as a philosophy; I will surely learn something.
A toast to differences.....