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: Greg R_
Date: 2008 Jun 15, 22:29 -0700
From: Greg R_
Date: 2008 Jun 15, 22:29 -0700
Jeremy 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).
>>> 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).
>> 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.
Ah, I thought you were mentioning that you thought you
were "handicapped" in the exercise by being limited to only some basic plotting
gear (triangles, dividers, etc.). I used parallel rules, C-Through plotter
(great for drawing LOPs perpendicular to azimuth lines), plus dividers, compass,
etc. to work my own plot.
>>> (wouldn't have reams of paper in the
Lifeboat).
But.... with a height above water estimated at 20'
that's some humongous lifeboat - and the problem did say something about being
"washed up on an unknown shore". Students, RTFP... ;-)
--
GregR
----- Original Message -----From: Anabasis75@aol.comTo: NavList@fer3.comSent: Friday, June 13, 2008 8:14 PMSubject: [NavList 5435] Re: 3-Star Fix - "Canned Survival Problem"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: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).I'm not quite sure what you're getting at here. About the only thing I reallymissed was my regular pocket calculator when doing this. The computeris nice and fast, but not really necessary. I am so used to doing these sightswith just books and plotting tools, I never learned to miss any electronicgadget except a calculator to make the arithmetic a bit quicker and dothe 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 229Greg replied
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; wholelatitudes 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?... ;-)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
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