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From: Frank Reed (no email)
Date: Mon Jun 06 2005 - 22:49:05 EDT
George H wrote:
"It certainly does. It extends the Noon sight to a protracted series of 9 to
13 observations extending over 40 to 60 minutes around noon. Can this still
be described as "a noon-sight"? "
It can easily be as few as five or six sights. Whether you call it "noon
anything" is up to you. But clearly this method is only a minor extension of
what one does for a normal noon latitude sight. And the beginners I've explained
it to seem to find no particular difficulty with this description. That is,
they "see it" as a noon sight.
And:
"Frank's proposal, though the best way to do the job of finding longitude
around noon, is quite a protracted operation. On how many lightly crewed
small craft can a crew member be spared for a period of 40 to 60 minutes
around noon each day while he takes such a series of shots at 5-minute
intervals?"
No, it is NOT a protracted operation. There is no requirement that the
sights be taken every 5 minutes like clockwork. Every "five or ten" as time (and
interest!) permit. As for the suggestion that someone has to give up 40 or 60
minutes of their day, gimme a break. It takes about a minute to take and
record each sight. You could easily make --and eat-- lunch during that time
taking a break every five or ten minutes for a quick sun sight.
And:
"There may be some interesting implications in what Frank is saying here.
With this method, he is teaching a way of finding lat and long that is only
available if the Sun happens to shine around the moment of noon. That's the
position navigators were in prior to Sumner, when if they lost their noon
(or near-noon) observation, both lat and long were unavailable until the
next sunny noon."
First, this is inaccurate historically. Sumner's discovery was considered an
"exotic" sight method for decades. It was rarely used in practice. Well into
the twentieth century, many vessels were navigated by traditional noon
latitude and afternoon/morning time sight. But back to your main point -- yes, of
course, this method is limited to those days when it is clear or partly
cloudy around noon. But so what? Celestial navigation is NOT a primary method of
navigation any longer.
And:
"So I ask; is he also teaching intercept methods to those same students?
Perhaps (though I hope not), at Frank's institution, the revolution in
navigation, which occurred with Sumner and Saint-Hilaire, has already been
discarded."
Let me clarify first that I am not formally affiliated with any
"institution" at this time, and I have only informally taught the little method I've
described. I have informal connections with Mystic Seaport in Mystic, Connecticut
(and have been employed there on and off in the past), and I do occasional
programs there. But I can tell you exactly what is taught there for celestial.
There is a standard 8 to 10-week course on celestial navigation using H.O.
229 with Sue Howell's Practical Celestial Navigation as the course book (this
book was written by Sue based on her direct experience with these classes in
the 1970s). There is also a one-afternoon class on latitude by noon sun,
which will perhaps be extended soon with the method for longitude I've described
if we can hone it down to short enough instructions. Of those two classes,
the noon sun afternoon fills up with eight or ten students once every four
months or so. Presently, the full length class draws rarely more than two or
three students once a year. Twenty-five years ago, the full length celestial
class filled to capacity three or four times a year. People are still genuinely
interested in celestial navigation, but since it is not a primary method of
navigation today, they are much less likely to set aside the time and effort
required for a full length course. Unless, of course, they are hard-core
enthusiasts like most of the people on this list.
And:
"Does he teach how a position line can be obtained from any altitude of any
celestial body, at any time, all in exactly the same way, from an assumed
position?"
Personally, I am willing to teach whatever the market will bear.
And:
"If all that has been lost (and I hope it
hasn't), it would be a very crippled 19th-century navigator that would
emerge from the course."
Just to be clear,the method I have described for getting lat and lon by noon
sun was NOT used in the 19th century. It is a modern method. Short, easy to
teach, easy to learn, easy to RE-learn in one sitting, and requiring no
special tables beyond four or five pages of basic almanac data which would be
valid for decades. It is not a cheat. It is not "fake" celestial navigation. It
does have some limitations, as do all methods of celestial navigation.
As for your use of the words "crippled" and "poor" and so on, your are
engaging in shameless exaggerration.
And:
"I ask nav-L members if they would be happy to cross on ocean, without GPS,
with a "navigator" who had learned his craft in that way, and was unable to
handle any other observations than those of the Sun at noon."
Without GPS?? If my GPS fails, I certainly hope that someone onboard has had
the common sense to bring a handheld unit. NO ONE is dependent upon
celestial navigation except for their own amusement (=challenge, enthusiasm,
pleasure, etc.).
-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
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