Azimuth of the sun calculations...HELP!

Maritime Topics Maritime Training & Licensing
1

Help! :confused::confused:

Iā€™m trying to work through azimuth of the sun calculations. Iā€™ve forgotten how to re-calculate the latitude (L), Dec, and LHA, listed as ā€œ1. 2. 3.ā€ at the bottom of the format for Azimuth calculations.

Can anyone help me figure out how this is done? Iā€™m studying for my 1600 ton master exam.

Thanks,

Curt

2

Latitude. Round it to the nearest whole number.
Find your Declination
Find your t angle = GHA
+m & s
W-/E+ +/- longitude

This will give you your LHA. If it is more that 180 the subtract 360 and your t angle is east. If this number is less than 180 the LHA is t angle and it is W. If you subtract upside down the t-angle is east. ALways make sure to go to the nearest Observed Longitude to make LHA a whole number.

Sto1 Lat
Sto2 Dec
Sto 3 t-angle

Subtract if lat and declination are contrary add if Lat and dec or the same
rcl1 cos x rcl2 cos x rcl3 cos +/- rcl 1 sin x rcl 2 sin = 2nd sin = HC

Sto1 LAt
sto2 DEC (make this negative if lat and dec are contrary)
sto3 HC

rcl2sin -(rcl1 sin x rcl3 sin) = divide rcl1cos divide rcl3 cos = 2nd cos = Z

If take lat north or south and t angle east or west

NE Z=ZN
SE 180-Z=ZN
SW 180+z = ZN
NW 360 - Z = ZN

3

[quote=curtgetz;25935]Help! :confused::confused:

Iā€™m trying to work through azimuth of the sun calculations. Iā€™ve forgotten how to re-calculate the latitude (L), Dec, and LHA, listed as ā€œ1. 2. 3.ā€ at the bottom of the format for Azimuth calculations.

Can anyone help me figure out how this is done? Iā€™m studying for my 1600 ton master exam.

Thanks,

Curt[/quote]
Curt, I just got home but in the morning I will respond to your message with a format and trig calculations as was probably taught to you at L.E. Fletcher if the one Capt. Lee doesnā€™t work for you. His is good and I have used it but is not formatted the way you probably are used to doing itā€¦Steve.

4

capt leeā€™s method is a good one to use, more importantly it is the method used and explained in the books & tables you can reference during your upcoming examination. for this reason alone I personally recommend using this system: if you get in a jam during during the exam itā€™s nice to know youā€™ve got that! in fact, I have always made a point of training myself from HO229 etc then when in the exam double checking my work.

good luck with your studying.

5

1. Lat to one decimal place
2. Declination to one decimal place, if contrary to Lat. enter as negative
3. LHA to one decimal place if over 180 enter as negative

Solution using 36X calculator: R 3sine divided by (R 1cosine times R 2tangent minus R 1sine times R 3cosine)=secondDD tangent=Z. If answer is negative add 180=Z
R means recall
Z to Zn see Pub. 229 or 249
Remember to use parenthesese after, R 3sine divided by, or solution will be wrong. Iā€™m about to go to Biloxi to gamble but if you need more helpā€¦text me at 251-581-1899ā€¦Steve

6

[quote=Capt. Lee;25941]Latitude. Round it to the nearest whole number.
Find your Declination
Find your t angle = GHA
+m & s
W-/E+ +/- longitude

This will give you your LHA. If it is more that 180 the subtract 360 and your t angle is east. If this number is less than 180 the LHA is t angle and it is W. If you subtract upside down the t-angle is east. ALways make sure to go to the nearest Observed Longitude to make LHA a whole number.

Sto1 Lat
Sto2 Dec
Sto 3 t-angle

Subtract if lat and declination are contrary add if Lat and dec or the same
rcl1 cos x rcl2 cos x rcl3 cos +/- rcl 1 sin x rcl 2 sin = 2nd sin = HC

Sto1 LAt
sto2 DEC (make this negative if lat and dec are contrary)
sto3 HC

rcl2sin -(rcl1 sin x rcl3 sin) = divide rcl1cos divide rcl3 cos = 2nd cos = Z

If take lat north or south and t angle east or west

NE Z=ZN
SE 180-Z=ZN
SW 180+z = ZN
NW 360 - Z = ZN[/quote]

The easiest way I can remember if ā€œtā€ is E or W is that if it is a morning shot ā€œtā€ is east and an evening shot ā€œtā€ is west (the sun rises in the east and sets in the west)

7

Man, I really am old school, (did my first one when I was 19yo). I just bust out a pencil and do it on scratch paper, per the example in the front of the 229.

8

I can do it like that too. That is actually how I learned to do it and then I took a celestial class at Delgado and these two old Sealand Captains made me use the calculator. I told them I already knew how to do it my way, but they convinced me and I am glad I listened.

I took the Chief Mate/Master 1 Week Celestial at Star Center in Dania and all those guys there use 229. It is easier and faster for me to use the calculator/keystroke method to sight reduction. After using this method a million times I will never forget this formula.

9

I learned using HO 214. The captains and mates I sailed with on deliveries refused to use 229. The pocket calculator hadnā€™t been invented at that time.

One old retired United Fruit Co captain told me anything other than 210 or 214 was a shortcut and ā€œreal navigatorsā€ wouldnā€™t take shortcuts. I later caught him using Coogleā€™s 2 Minute Azimuths.