LHA in Eastern longitudes?

[craigsl]

I'm at a loss to understand how to calculate LHA while sailing in Eastern longitudes.

What I know;

LHA in Eastern longitudes=  GHA + ApL (Assumed position longitude) (minus 360° if necessary)


Example;

Date-  November 25, 2022
GMT- 10:10:59

ApL=  E 025° 45'

GHA= 336° 00.7'

LHA=  336° 00.7' + 25° 45'= 361°45.7' - 360° = 1° 45.7'

But, here's the confusion, LHA in Eastern longitudes is supposed to be rounded up or something like that and I'm not really sure if it is supposed to be rounded up.  Information on the web is vague and not explained well enough making too many assumptions.  Another possibility is that very few who speak English are sailing, doing CN, in the Eastern hemisphere.

So, my estimate to solve the problem is simply this (tell me if I'm wrong)

Eastern longitudes, LHA= GHA (whole degree's) + ApL (whole degrees) + 1

The problem above could be easily solved like this-  LHA= 336° + 25° + 1° (minus 360°) = 2°

Any ideas about this?

Greetings, CelNav57


I think you are right.  I would just make LHA a round number by making assumed lloongituda 26 deg. Therefore   336 +26 =362.  362-360=2 deg. I saw this method in a few books. When you take 25 deg instead of  26 , you  make LHA smaller, because  to round 25.45 to 25 is much more "rounding" than from 25.45 to 26.  

Anyway,  your assumption is correct  the way I see it. Again,  I  saw the examples of  calculating LHA in Lat.E   and it is exactly  how it was done.  And,  by the way,  you  may use   LHA  of 1 deg 45.7  for your calculations but  then you  need to go through correction tables which  anyway  will round up the final result. 

This is the way I see it.  

Thank you!

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This little attachment shows much  more clearer what I meant, that  my  previous post ;>

That was my conclusion as well.  I was watching a video on youtube by the eminent sailor and USCG officer, Chris Nolan, in which he explains about LHA in Eastern longitudes. LHA eastern longitudes

In the video he says that LHA must add up to a whole degree and he explains the procedure.  To me it seems simple;
Add the GHA whole degree (no minutes) and add the Ap longitude whole degree (no minutes) then just add 1° to the result.  Simple.  Even still the St. Hillaire method will get you the same basic LOP.

Oh, below is a quote I found on Chris Nolan's site, PracticalNavigator.org  and look who said it!

“Whenever I meet with the words 'Thus it plainly appears,' I am sure that hours and perhaps days of hard study will alone enable me to discover how it plainly appears.” 

                                             ― Nathaniel Bowditch