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From: George Huxtable (no email)
Date: Tue Jun 07 2005 - 10:09:24 EDT
There are some points to pick up from Frank's many recent postings.
I had written, about his proposed method for "noon" longitude, which he had
said "goes a little beyond the standard procedure for shooting the Noon Sun
for latitude only"
"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"? "
and he replied-
"It can easily be as few as five or six sights."
My figure of 9 to 13 observations was deduced directly from his own
proposal: for observations every 5 minutes over a period from 20 - 30
minutes before noon to 20 - 30 minutes after noon.
I added-
"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?"
to which came the reply-
"No, it is NOT a protracted operation."
Indeed it is. "Protracted" means "drawn out in time", which it certainly
is, at 40 to 60 minutes, when compared with the usual noon-sight for
latitude.
Frank added-
"There is no requirement that the
sights be taken every 5 minutes like clockwork. Every "five or ten" as
time (and
interest!) permit... "
But that doesn't alter the protraction.
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.
Well, if I had a crew member would be devoting the next 40 - 60 minutes to
such closely-spaced observations as Frank has suggested, I wouldn't expect
much useful boatwork out of him in the 2 or 3 minute free intervals in
between.
In reply to my-
"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."
this from Frank-
"First, this is inaccurate historically. Sumner's discovery was considered
an>"exotic" sight method for decades. It was rarely used in practice."
Even if that was the case (and he has provided no evidence for that
sweeping statement), in what way would it make my previous sentence
"inaccurate historically"?
he continued-
"...Well into
the twentieth century, many vessels were navigated by traditional noon
latitude and afternoon/morning time sight."
That may be. So what?
Frank-
"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."
It seems to me, then, that a teaching programme, confined to around-noon
Sun observations and no others, will produce pseudo-navigators who may
delude themselves into thinking that they can determine lat and long from
celestial observations, but are in fact only safe on a vessel that is
actually being navigated by GPS.
What would be the name of such a course? If some sort of certificate is
provided as a result, how would it be worded? Would it form a required part
of any other qualification?
Referring to position-line navigation, I added-
"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."
Frank-
"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."
Well, noon by equal-altitudes has been around since long before the 19th
century, but primarily for on-land use as it was regarded as insufficiently
accurate at sea. What's so specially new that makes Frank's a "modern
method?
Frank-
"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."
A phrase Frank used in another posting, "instant gratification", describes
what is being offered, perfectly. I don't think I used the word "fake", but
perhaps "facile" would be more appropriate. If without GPS, then I would
prefer to be guided by a navigator trained in the 19th century, rather than
by a product of Frank's proposed class. If navigating by GPS, NEITHER is
needed.
I don't withdraw my description of the man emerging from Frank's proposed
class as a "crippled" navigator. Indeed, I wonder if he will even be aware
of what it is he is missing.
Finally, may I say that an important aspect of position-line navigation, to
me and perhaps to others, is its universal application, together with its
basic simplicity, and indeed, its intellectual beauty. True, in applying
it, there's a lot of hard graft with tables, which can be bypassed with a
pocket calculator if preferred. Nothing that's worthwhile comes easy.
George.
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contact George Huxtable by email at , by phone at
01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy
Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
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