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Heh... I almost wrote the exercise with all of the navigation books
being lost overboard too, and luckily the intrepid navigator had
memorized their entire contents - but figured that was a bit too much
of a stretch. Now I may have to re-consider that option...  ;-)

Assuming you're not being tongue-in-cheek with your solution (and being
at work I can't verify it right now), regardless of accuracy you
definitely get the Most Unique Solution award (plus an honorary
Navigator Who I'd Most Want To be Shipwrecked With plaque, with gold
clusters).  :-)

--
GregR



--- "Gary J. LaPook"  wrote:

> Being the conscientious navigator that I am, I followed my usual 
> practice of memorizing some data from the 2008 Nautical Almanac so
> that 
> I would have it available for emergency use.
> 
> The first thing I memorized was the GHA of Aires at 0000 Z January 1,
> 
> 2008 which is 100� 01.9' and also remembering that Aires advances 
> 59.139' each day. With this information you can calculate GHA Aires
> for 
> 0000 Z on June 9, 2008 which is the 161st day of the year but is only
> 
> 160 days from January 1st. So multiplying 59.139' times 160 days
> gives  
> 157� 42.2'  to which you add the starting value of 100� 01.9' to come
> up 
> with the GHA Aires on June 9th at 0000 Z of  257� 44.1'. To this you
> add 
> the change of GHA for the time since 0000 Z (3 hours 42 minutes 10 
> seconds for the Vega shot) by multiplying the time interval by the
> rate 
> of change of 15.041� per hour making 55� 41.6' making the GHA Aires
> at 
> the time of the Vega shot of 313 � 25.7'.
> 
> I also memorized the SHAs and the Declinations of ten of the
> navigation 
> stars ( nobody could memorize all 57) which should be enough for 
> emergency use as tabulated for July 1st so that the values will be 
> reasonable for the whole year. Fortunately this included the three
> stars 
> used in this exercise. So now adding the SHA of Vega, 80�  41' we end
> up 
> with the GHA of Vega of 34� 06.7' and using the D.R. as the A.P. we
> get 
> an LHA of 274� 48' and the declination of 38� 47' N. (rounded to the 
> whole minute)
> 
> Using these values on my Bygrave slide rule (see attached work sheet)
> 
> since I have no tables with me, I computed Hc of 23� 59'.
> 
> The Hs given was 24� 05.5' Computing the dip correction in my head of
> 
> 4.5' (the square root of 20 must be between 4 and 5 ) and applying
> the 
> refraction correction of minus 2 gives an Ho of 23� 59' giving and 
> intercept of zero and an azimuth of  58.1 �.  I long ago memorized
> the 
> refraction table for altitudes above 10� in The Air Almanac and in
> H.O 
> 249, the cutoff values are 63-33-21-16-12-10� , zero above 63, 1
> above 
> 33, 2 above 21, 3 above 16, 4 above 12 and 5 above 10.
> 
> I used the same procedure for Spica and Pollux getting another zero 
> intercept for Pollux, Zn of 290.2� and a  4 NM away for Spica with a
> Zn 
> of 171.7�.
> 
> Since I am on the road I do not have any of my plotting tools with me
> so 
> I had to make do with what I found in my briefcase. I used my MB-2A 
> flight computer since it had an azimuth scale and I used a pad of
> paper  
> with a right angle at the corner as my straight edge for plotting the
> 
> LOPs. I used a tape measure from IKEA to measure the length of the 
> intercept (see photo.)  I plotted the LOPs and found the fix by 
> bisecting the three angles giving a fix .4 NM west of the A.P. (D.R.)
> 
> and 2.8 NM north of it. (Plotting a fix as a distance from the A.P.
> like 
> this is common in aerial practice and it is often done on an E-6B.) 
> Adding the 2.8 NM north to the D.R. latitude gives a fix latitude of
> 34� 
> 16' North. To convert the .4 NM west  to a longitude you divide the
> .4 
> NM by the cosine of the latitude, .82, to find the difference in 
> longitude of  .5' so the fix longitude is 119� 19.5' West (rounded to
> 
> either 119� 19' or 20'.)  ( I got the cosine of 34� by finding the
> sine 
> of 56� on the MB-2A sine scale, used for wind correction
> calculations.)
> 
> My fix might not be in agreement with others but I used a refraction 
> table tabulated in whole minutes, I only memorized the stars'
> positions 
> to the nearest minute and I did not have any plotting tools to use
> but 
> my position is certainly good enough for emergency navigation and
> done 
> without an almanac, tables or electrons.
> 
> (I will have to send the images when Ii figure out how to make them 
> smaller.)
> 
> gl
> 1
> 
> m_burkes@msn.com wrote:
> 
> >Captain Lecky would be proud of those dividers ha! Speaking of
> >interpolation I have found a neat way to get around that pesky DSD
> and
> >interpolation tables by using the aviation E6B computer or the
> >equivalent nautical slide rule. Essentially the set up:d-value/60=d-
> >correction/declination minutes. Yes the calculator offers the proof.
> >Mike Burkes
> >On Jun 12, 11:44 pm, Anabasi...@aol.com wrote:
> >  
> >
> >>Thanks for the nice exercise Greg.  I literally had to dust off the
>  ship's
> >>Vol III of HO 229 and deflower a Plotting sheet 925 to work this
> one  out.
> >>
> >>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).  I have
> attached a  
> >>picture in to this message with the plot and the tools.
> >>
> >>My Lat is a bit lower (plotting or math error?).  I used an assumed
>  position
> >>method and HO 229.  I had to assume we were drifting and no 
> current (didn't
> >>advance or retard the lines).  I had not done a full HO 229  paper
> reduction
> >>of a star in many years, and I had to think a second to remember 
> how to use
> >>the interpolation pages on the inside covers for the declination 
> interpolation.
> >> I usually whip those off with the calculator.  Still,  I got
> pretty close to
> >>the computer solutions with Lat 34deg 11.9' N and  Longitude 119deg
> 16.0'W.
> >>
> >>As to how you would get an Eastern sight on the west coast, you
> would have  2
> >>options in general.  The first would be a back sight.  This would
> be  
> >>particularly difficult with a regular sextant at such a low
> altitude.  The  other
> >>option would be to use a bubble sight tube or other artificial 
> horizon.  If you
> >>were across a bay, you could also use a dip short of  the horizon
> table.  
> >>That's all I can think of at the moment.
> >>
> >>Jeremy
> >>
> >>**************Vote for your city's best dining and nightlife.
> City's Best
> >>2008.      (http://citysbest.aol.com?ncid=aolacg00050000000102)
> >>
> >> gregExerPlot.jpg.JPG
> >>182KViewDownload
> >>
> >> GregExerTools.jpg.JPG
> >>129KViewDownload
> >>    
> >>
> >>
> >
> >  
> >
> 
> 
> > 
> 


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