AP in the east.

[Rumata]

I think the instructions for Sight Reductions needs to have something like the following:

*  Assumed Position for east longitude use DR longitude integral degree plus 60'-GHA minutes for the minutes, If you are at 35° east and the GHA minutes are 33' then AP is E35° 27'  (60'-33'=27') 
The instructions work for West.

Greetings, Wannathermal.

Your suggestion makes sense.  But I use ( as an exercise, of course) very simple method :

For the West, assumed longitude , which I use to calculate LHA is equal to the DR longitude in degrees  and minutes equal to the minutes of GHA.  To make LHA even.  For instance, Dr  lat. 26 deg. 31 min. N, Dr long. 90 deg. 55.2  min. W,  GHA sun 52 deg. 38.1 deg min  Now, Assumed  long. is 90 deg. 38.1  min.  Therefore,  LHA =90.38.1 - 52. 38.1= 38-0 East.

East version, use the same approach just to make sure LHA is even. Well, need to admit the fix was never within 2 miles.  Always a little bit more.

Anyway, it works for me.

Again, thanks for the interesting approach.

Rumata

What is your Ap for Eastern DR's? Could you show an example with a plot. I like the ease of your approach but I have found that the plotted LOP can be up to a degree off if you round the Ap longitude the wrong way.

Bob (always looking for the easier way) McDowell

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Just to be clear, Ap (Assumed position) is not the same as DR (Ded Reckoning), nor with the intercept method should it be. DR is the position of the vessel calculated using speed, time and course from your last fix. Ap is a position derived through GHA and DR Lat and Lon using the whole degree integer for Lat and the whole degree integer with the minutes derived through addition or subtraction.
When using the tables it is important to get the Ap longitude correct so your LOP bisects the azimuth of the celestial object and your DR (within 5-10 miles)

Rumata, if your approach works within 5 miles then keep up the great work.

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As an exercise please reduce and plot the following to check the different Ap formulas discussed above. In this case the daily running sun fix was within 2 miles of the DR positions.
17 Feb 2018    (UT)       12:18:50            13:40             15:32
DR Lat                          N38°09'             N38°02'          N37°54'
DR Long                       E15°38'              E15°37           E15°46'
HO HS corrected            37°35.5'             29°25.5'         110°21'
Again, these numbers are from the sights taken aboard during our last trip from Les Sable d'Olonne on the Atlantic French coast to Sukosan, Croatia. A cold but great trip. We stayed in between the nastier weather and averaged 7.5 knots for the whole trip.

I'll try to reduce your example data later-need to go now-but below is my approach ( not my, but what I'm using) in dealing with it

Greetings, just as an example (My exercise)
 
Latest fix:
Lat. 39deg.35’N, Long. 001 deg. 05’ E
--------------------------------------------------------
DR (one hour later):
Lat. 39deg 39’ N, Long. 001deg14’ E
-------------------------------------------------------------
To use Pub. 249
LHA aries  = GHA arries +Long. Assumed.;
GHA aries=164deg. 33.9’
To make LHA aries even, I consider Long. Assumed 001deg. 26.1’.
Then,
LHAaries=164deg.33.9 +001deg.26.1 = 166 deg.
For Jupiter, time of observation GMT=19-23-08, Hsextant=45 deg.00.8
From NA GHAjupiter=331deg. 07.2
Using v and time corrections, GHA Jupiter= 336-55.2
------------------------------------------------------------------------------------------
LHA Jupiter= GHA +Long. Assumed.
To make LHA Jupiter even,
I consider Long. Assumed 1-04.8.  Therefore, LHA Jupiter = 336-55.2 +1-04.8 = 338-00
 
So, AP has the following coordinates, Lat.39deg.N, Long= 1-04.8E.
 
After it, using standard procedure , I find intercept and azimuth.
 
Thank you

Greetings, just as an example:
 
Latest fix:
Lat. 39deg.35’N, Long. 001 deg. 05’ E
--------------------------------------------------------
DR (one hour later):
Lat. 39deg 39’ N, Long. 001deg14’ E
-------------------------------------------------------------
To use Pub. 249
LHA aries  = GHA arries +Long. Assumed.;
GHA aries=164deg. 33.9’
To make LHA aries even, I consider Long. Assumed 001deg. 26.1’.
Then,
LHAaries=164deg.33.9 +001deg.26.1 = 166 deg.
For Jupiter, time of observation GMT=19-23-08, Hsextant=45 deg.00.8
From NA GHAjupiter=331deg. 07.2
Using v and time corrections, GHA Jupiter= 336-55.2
------------------------------------------------------------------------------------------
LHA Jupiter= GHA +Long. Assumed.
To make LHA Jupiter even,
I consider Long. Assumed 1-04.8.  Therefore, LHA Jupiter = 336-55.2 +1-04.8 = 338-00
 
So, AP has the following coordinates, Lat.39deg.N, Long= 1-04.8E.
 
After it, using standard procedure , I find intercept and azimuth.
 
Thank you