NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Practice CN on cruise ship
From: Gary LaPook
Date: 2017 Oct 24, 15:32 -0700
From: Gary LaPook
Date: 2017 Oct 24, 15:32 -0700
Norm - I may have missed it, but observing sun set and sunrise are opportunities to get a LOP without a sextant - all you need is a good watch, and an approximate DR. A compass is helpful but not necessary. You can use your sextant for the observation but do not need to measure altitude (HS) - it is (obviously) zero. Note that HO will be negative. Cheers! > Thanks all for your sage advice. Can't wait for our trip to commence.
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I also took 3 observations of the upper limb of the sun at sunrise without a sextant, just watching the top of the sun appear to pop up on the horizon with just my Mark one eyeballs. The intercepts for these observations were 3.0A; 4.7 T; and 0.6A, a σ of 3.93 NM, not as good as with a sextant at higher altitudes but still a useful level of accuracy.
http://fer3.com/arc/m2.aspx/Accuracy-sextant-observations-sea-LaPook-sep-2010-g14008
gl
