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Paul is correct, as he usually is.

I don't think I ever did use that technique in real-life; only as a
classroom exercise. It's really more a technique for surveyors, in my view,
than for the rough-and-ready navigation of small-craft cruising. It's like
quite a lot of such stuff that you get taught; you learn it, but never use
it.

Instead, I would do the job with a French Opticompas, a nice hockey-puck
instrument, taking two or three (sometimes more) nearly-simultaneous
magnetic bearings of landmarks or seamarks. I would shout the numbers out
to my wife Joan, at the helm, in order, for her to remember. Except the
last one, which was all I could manage to keep in my own head. All this
would take a couple of minutes at the most.

At the little chart-table, from the last of the bearings, I would subtract
the variation, and scribble the answer somewhere on the margin of the
chart. Then Joan would recall the others to me, in sequence, from her
reliable memory-bank. And so on. Plotting the three reciprical bearings
took little time, and resulted in a cocked-hat that was usually acceptable.
In rough weather, the triangles would be bigger, but you took what you
could get.

I've done that little pilotage job so often, I reckon I could do it in my
sleep. Maybe, on night watches, sometimes I did.

George.

contact George Huxtable, at  george@hux.me.uk
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
----- Original Message -----
From: "Paul Hirose" 
To: 
Sent: Saturday, December 04, 2010 7:55 PM
Subject: [NavList] Re: Horizontal Sextant angles plot.


| George Huxtable wrote:
| > But around that same time, at a yachtsman's navigation evening-class in
| > Britain, I was being taught the same technique, and it is detailed in
| > Cotter's "Elements of Navigation" of 1953, and likely many other texts
of
| > earlier date.
|
| In practice, how much did you use circles of position derived from
| horizontal sextant angles? I imagine the observations and plotting would
| be difficult on a small craft with cramped quarters and tiny crew.
|
| --
| 
|
|
|

   

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