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post #10 of Old 01-13-2013
erps
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Re: sextant practice

Quote:
I downloaded "Step-by-Step Sextant User's Guide" and ordered the Mark 3 sextant and the artifical horizon to practice on. Can anyone give me a brief primer on what I am going to have to do to correct for the fact that I am above sea level when taking my sights?
My recollection is that the altitude you're concerned with is your altitude above the horizon. On the sea, that's the height of you eye above sea level. If you were in a shore side building, using the sea as your horizon, then your altitude would need to be applied. But it's my recollection that there is no DIP correction (height of eye above water/horizon) when using an artificial horizon, but the angle of the celestial object you're taking your sight on will be half of the angle indicated on the sextant.

They used sextants in airplanes to get around in the old days with artificial horizons and altitude didn't play into it (IIRC)

Ray
S.V. Nikko
1983 Fraser 41
La Conner, WA


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Boating for over 25 years, some of them successfully.
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