NavList:

Alex,

It is not ridiculous to have the three armed protractor (position pointer) measuring to 1' moa. Cartography and chart sounding updates would require this precision. Back in the cold war days before GPS nuclear ballistic missile submarines needed the precision of 1' moa to pin point the position of launch. The sextant would be the means to measure the horizontal angle rather than taking bearings using a bridge wing gyro repeater.

Greg Rudzinski

[NavList] Re: Current Sextant Manufacturers
From: Alexandre Eremenko
Date: 31 Mar 2012 08:43
Bill and Geoffrey,
I gues no modern (XX century) navigation manual mentions back sights
or Lunars. But all of them mention horizontal angles between shore
objects. This is what "sextants" and more that 100d arcs are for.
You can frequently see a "3-armed protractor", the device that permits
to plot your position from two such angles without any calculation.

I have one of those "protractors": it has a ridiculous accuracy of 1'
(complete with 2 sextant-type drums and worms!).
Ridicuous for a plotting device,
of course. So its accuracy is higher than the size of a pencil
dot on a map. This was
certainly intended to use together with a sextant.

Alex.

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