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Hi Dave,
         I also made a wooden instrument - a octant - it is not terribly
accurate (+/- 5NM at best ) but as a historical
reenactor I needed something that looked period (circa 1775) for
"show-and-tell" demos. One of these days I am
going to make another, or (if I can find one cheaply on ebay); restore
one. I love navigation in this time period and
have also made myself a log line and lead line. It is fun to do on the
bay or sound.
~Greg


On 02/01/2015 04:11 PM, David Pike wrote:
You can always make your own.  Around 1982, I had to make something as
my final testpiece for my Post Graduate Certificate in Education as a
tyro Craft, Design, and Technology teacher.  I'd always regretted
allowing my mother to give my father's marine sextant away, and even the
plastic ones seemed very expensive, so I decided to make my own out of
plywood.  The trick is to make it big, as people like Tycho Brahe
found.  Then cutting the scale is easy.  I seem to remember the
technician in the workshop showing me how to use a dividing engine as a
lathe attachement, but I'd never be able to remember how to use it now.
I recall shooting stars on a bowl of water on a still night and being
surprised to find the Hs was double what I'd expected.  Taking instant
values compared to always using an averager were also a pleasant
surprise.  I've got the shots I took somewhere around. As I recall it
was accurate to 2 or3nm.  My problem is no natural horizon.  As soon as
I get my new artificial horizon working, I'll have to start playing with
the plywood again.  Dave

   

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