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Subject: Re: astrocompass still in use
From: Robert Eno (enoid@XXX.XXX)
Date: Thu Sep 26 2002 - 21:55:58 EDT
Interesting application.
How on earth did you manage to keep your astrocompass perfectly level whilst
it was mounted on your boat?
Robert
----- Original Message -----
From: <jcs@XXX.XXX>
To: <NAVIGATION-L@XXX.XXX>
Sent: Thursday, September 26, 2002 8:15 PM
Subject: Re: astrocompass still in use
> Quoting Paul Hirose <paulhirose@XXX.XXX>:
>
> > The astrocompass lives on. A major utility company in California
> > allows engineers and architects to borrow one to evaluate solar access
> > to a building site. Here is their online manual:
> >
> >
>
http://www.pge.com/003_save_energy/003c_edu_train/pec/toolbox/tll/app_notes/
astr
> o_comp.shtml
> >
> I have an Astrocompass and I have fixed up a mounting on my boat for it. I
used
> it about a year ago to check the Deviation of the boat's compass and a
very
> interesting afternoons exercise it was too. I wonder if anyone else has
found a
> use for this old faithful.
> First the instrument was mounted and levelled. The Latitude was set on
the
> micrometer scale and the Declination of the Sun set very roughly on the
> sighting bar. The LHA of the Sun changes slowly so I wrote a simple
program on
> a Ti82 calculator to give the value to set on the LHA drum for every
minute of
> time and this was re-adjusted accordingly.
> Next the boat was carefully steered on 12 different COMPASS headings
at 30
> deg increments and the Astrocompass rotated to bring the Sun's shadow of
the
> sighting bar onto the plastic graticule. At this point the TRUE direction
of
> the boat was read of the base scale. Adding Variation to this data
produces a
> list values for plotting the Deviation correction graph.
> I have no idea of the origin of this instrument and I would like to
hear if
> anyone in the group does. I was taught how to use it in a Coastal Command
> Lancaster many years ago and my instructor then had used one when flying
over
> the Libyan dessert during the war. His magnetic compass had been destroyed
by
> an enemy bullet.
> I have an instruction book. If any one would like a copy my email is
> jcs@XXX.XXX
>
> Clive Sutherland.
> Wantage, (where King Alfred burnt the cakes).
> 51deg 38.2 min N 001deg 24.5min W
>
>
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