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Originally Posted by poor sailor
Well, now I'm starting with this great mod. I learned how to use the sextant, but how to use the sunset/rise table and how to calculate longitude, is there any formula to get this? Sorry, maybe is there in your manual Van, but I couldn't understand well I think.
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saw your question, but it's not so easy to explain - it will take a while
(anyone can jump in here and help or correct me)
IMHO the accuracy from sunrise/sunset spotting is not very good. And you only get longitude this way.
You still have to know latitude in some way and therefore you will need the sextant. To use vanjasts
suntables to solve for longitude you must know your latitude approximately to enter the table correctly.
by then the rule of thumb is: every 4min the sun moves 1° from east to west, every hour the sun moves 15°.
so an (maybe not so easy) example:
its 25/May/1943: you are at about 20° S Lat.
You want to know longitude, so you wait for sunrise. At 6:24 ship chrono you see this:
You note: I "estimate" sunrise at 6:24. Now enter vanjast's table to look for sunrise/set page of "Southern Latitudes ".
Look under line
25/may and column
20°S. Note the sunrise time you'll see
6:24 !
You are on spot on either meridian of 0° 15° 30°....... Now note the time difference between ship chrono and local time.
local time is 1 hour earlier, so you are exactly 15° W of greenwich.
Now imagine you saw the sunrise under same conditions at 6:32. Thats 8min later than table time.
So you'll have to add 2 more degrees to the west. Together with 15° W for 1h time difference (local-chrono) that's 17° W.
The hardest part in all this is: you'll always have to wait for the sun!
And I get varying results, maybe it's the way the sun is modelled in SH3. I'm more or less 2min = 30' accurate, that's half a degree.
note: If you travel at e.g. 24° Lat you'll have to interpolate in the table between times for 20° and 30°.