NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: long lost lunars
From: Fred Hebard
Date: 2003 Dec 8, 10:05 -0500
From: Fred Hebard
Date: 2003 Dec 8, 10:05 -0500
------------------------------------------------------------------------ Frederick V. Hebard, PhD Email: mailto:Fred@acf.org Staff Pathologist, Meadowview Research Farms Web: http://www.acf.org American Chestnut Foundation Phone: (276) 944-4631 14005 Glenbrook Ave. Fax: (276) 944-0934 Meadowview, VA 24361 On Dec 7, 2003, at 10:13 PM, Frank Reed wrote: > Bruce Stark wrote: > "In the way we work our lunars you and I are at different ends of the > spectrum. I do everything the old way, not even graphing or plotting. > I find it satisfying to work observations the way the old navigators > did." > > I haven't been able to descibe all the approaches I've experimented > with in the brief time I've been on this list. I may have given the > impression that I'm in favor of computer solutions for lunars, but > that isn't the case. There are many options. > > And: > "But this approach is not going to take the world by storm. Most > people shy away from anything that calls for a skill they don't > already have, and the present generation has no skill at > pencil-and-paper calculation. They've had no reason to develop it. The > recruitment that will keep sextant navigation alive (and perhaps help > put the history of navigation on an honest footing) will almost > certainly come at your end of the spectrum." > > Anyone interested in celestial will eventually try the paper methods, > and since it is no longer a "practical" art, I think it's very likely > that more students will want the historical techniques instead of > electronic approaches and also they will likely bypass mid 20th > century methods like the highly refined H.O. tables. > > There are a number of reasons why we need computer solutions for > celestial navigation alongside the paper methods: > 1) Some celestial enthusiasts really have no interest in the > calculation. They want to see themselves handling a sextant, learning > to take sights with skill, but the reduction is somebody else's > problem. Those people are part of the market, so I don't disdain their > preference. > 2) A quick reduction with a few dozen strokes on a keyboard (or a cell > phone!) means you can take many more sights. Practice makes perfect, > and you can practice shooting lunars anytime when you get instant > feedback from electronic reduction. > 3) When you have a computer solution, you can do a ten-minute > introduction to lunars for students, friends, etc. They can see it in > practice and quick. Then those who want to can learn whatever paper > method suits them as time and interest permit. > > You also wrote: > "The only thing I take exception to is the idea that navigators had to > have a chronometer to see them through the four days or so of the dark > of the moon. Dead reckoning saw them through. Dead reckoning gave the > continuity the chronometer provided for later generations. The purpose > of nautical astronomy was simply to correct the reckoning now and > then. That kept it from drifting dangerously far from the truth as the > weeks and months went by." > > What I was getting at though is the next step beyond dead reckoning. > Yes, dead reckoning saw them through, and it's good enough to sail > around the world. It's what Slocum used for longitude as late as the > 1890s (plus one lunar distance). But accurate navigation is founded on > one simple thing: money. It's all about money. A ship that had > accurate longitude approaching a coast at New Moon could sail with > confidence and speed and get its cargo to port ahead of its > competition. DR was a start, but to beyond that they needed lunars AND > chronometers. > > By the same argument, for most smaller vessels, there was more profit > to be made by accepting a little risk and relying on dead reckoning > alone for longitude instead of spending money on a superior sextant > for lunar distance observations or, even more pricey, a chronometer. > > And why is celestial navigation almost over and done with today? > Because of price. When the price of two GPS receivers fell below the > price of one sextant, the show was over. > > Frank E. Reed > 75% Mystic, Connecticut > 25% Chicago, Illinois > >