NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: 3-Star Fix - "Canned Survival Problem"
From: Jeremy C
Date: 2008 Jun 13, 23:14 EDT
Greg wrote:
Vote for your city's best dining and nightlife. City's Best 2008.
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From: Jeremy C
Date: 2008 Jun 13, 23:14 EDT
I wrote:
> Since I was bereft of electronic gadgets, I did this with a plotting
> sheet, 2 triangles, a pair of dividers, 2 books, a pencil, and small
> piece of scratch paper (wouldn't have reams of paper in the
Lifeboat).
Greg replied:
> Since I was bereft of electronic gadgets, I did this with a plotting
> sheet, 2 triangles, a pair of dividers, 2 books, a pencil, and small
> piece of scratch paper (wouldn't have reams of paper in the
Lifeboat).
Greg replied:
Glad *somebody* actually noticed that part of the exercise (though
I
did say the navigator managed to grab all of the navigation tools
before abandoning ship, but your method is also valid).
did say the navigator managed to grab all of the navigation tools
before abandoning ship, but your method is also valid).
I'm not quite sure what you're getting at here. About the only
thing I really
missed was my regular pocket calculator when doing this. The
computer
is nice and fast, but not really necessary. I am so used to doing
these sights
with just books and plotting tools, I never learned to miss any
electronic
gadget except a calculator to make the arithmetic a bit quicker and
do
the interpolations. Now if you asked me to
do sailings using trig tables,
that would be a different story.
I wrote:
> I used an assumed position method and HO 229
Greg replied
I used 34° N and longitudes based on getting whole numbers for the
LHAs.
I used 34° N and longitudes based on getting whole numbers for the
LHAs.
When I say "assumed position method" that is exactly what I mean;
whole
latitudes and assumed longitudes to get whole numbers of LHA.
Greg wrote:
How about across a parking lot?... ;-)
Wonder if a dip short correction would have made that "artificial
sight" more accurate?... ;-)
Wonder if a dip short correction would have made that "artificial
sight" more accurate?... ;-)
Well the table in Bowditch for dip short of the horizon has a minimum
distance of about 0.2 nm, although you can probably use the formula to get
shorter distances, but I am not sure of the accuracy.. In any case, at 20
ft above sea level, your dip at 0.2nm is 56.7 minutes. I'm not sure how
that compares with your observed Hs and the Hs you got after the numbers were
massaged a bit. This whole idea might inspire me to shoot and then post an
exercise. Since the island is to our East, I should be able to shoot some
sunlines based on the shoreline. Radar will give me the range so we should
be fairly accurate.
Jeremy
Vote for your city's best dining and nightlife. City's Best 2008.
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