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Old 07-26-2013, 01:41 PM   #1
Sjizzle
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Default [TEC] Real navigation Tutorials

in this thread i will try to show u how to fix your position on the map without using the navigator From the game with TDW's UI and MagUI when DrJones will release the new version of the MagUI.
The math and others calculation are same with both UI's but there are difrent sextant.
Remember

we don't have a real sextant to calculate the sextant index error and make some other correction so we can be 100% accurate

First Tutorial:

Finding The Latitude

1. Noon Latitude

"Local Noon" is the exact time when the Sun reaches its highest point in the sky. This is also the time that it crosses the vertical, imaginary line, that astronomers call the "meridian".
This is a very simple method enabling the observer to determine latitude by measuring the maximum altitude of the sun (or any other object).
No accurate time measurement is required. The altitude of the sun passes through a flat maximum approximately(see noon longitude) at the moment of upper meridian passage (local apparent noon, LAN) when the
GP of the sun has the same longitude as the observer and is either north or south of him, depending on the declination of the sun and observer’s geographic latitude. The observer’s latitude is easily calculated by forming the algebraic sum or
difference of the declination and observed zenith distance z (90°-Ho) of the sun, depending on whether the sun is north or south of the observer.



now let's see this in game all what wee need is the alamanac from 1939 - 1945
an online almanac can be found here Click

to measure the sun angle click on the navigator the sextant and u will see the screen


after that click on Enable Sextant and align the te sextant to the water line ( horizont )



now search for the sun and measure the angle of the sun





as we see we have the sun at 42.54 degree no let's do some math to find the latitude
first we need to find
Zenith Distance = 90 - 42.54 we convert the 90 degree to 89.60 - 42.54 = 47.06 is the Zenith Distance
now let's see the sun declination at 1939. sept. 01 12:00 PM


Sun declination is N 8. 31 so now let's see we are in the same hemisphere ( N ) but the sun is belove us so we apply the
Latitude = Zenith Distance + Declination
Latitude = 47.06 + 8.31
Latitude = 55.37

now let's what the navigator say about our latitude



whoop 55.37 N pretty nice ha ?
if u find your latitude then u can find your way home or your destination at sea

when DrJones will finis the MagUI new version i will show u also with that UI mod.

PS.

if somebody have an 1939 - 1945 .PDF almanac and can share it with use i really apreciate it thx.


Last edited by Sjizzle; 05-01-2014 at 04:46 AM.
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Old 07-26-2013, 01:42 PM   #2
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Second Tutorial

Mark our position on the map and find the Longitude

Remember

we don't have a real sextant to calculate the sextant index error and make some other correction so we can be 100% accurate

Let's start with measuring the sun angle


Now we do the math to find the Lat.
Zenith distance = 89.6 – 42.51 = 47.09
Lat. = Zenith Distance + Declination
Lat. = 47.09 + 8.31 = 55.40N




u can download this spreadsheet from here Download


Each degree on the game map is 120 km.



Now let’s see how to market on the map without the navigator help
Each degree on the game map is 120 km.
We do again some math 120 : 60 = 2km
We know that assumed Lat. is 55 but how we find that 40 simple 40 x 2 = 80km
( when u draw from the bottom to the top u multiply and when u draw it from the top to the bottom u divide )
Let’s draw that 80 km on the map.





Now let’s find the Long
Open that excel work sheet and look at GHA there is 259.57 and to LHA where is 20.00
359.57 – 20 = 339.57 – 360 = -20.43
Long = 20.43E
We know that we are at Long. 20E now 43:2 = 26.5km let’s draw it on the map
( When u draw it from the west to east left side to right side u multiply and when u draw it from east to the west right to the left u divide)





Now let’s see what the navigator say as u see the navigator calculation is

Lat. 55.41N and Long. 20.47E so we are not far as i said we can’t be 100% accurate cos we don’t know the sextant index error and dip and other correction


this can be my error or the game error so we can not chek where is the u-boat to see wich one is correct but i think that is pretty good and give more realism to the game.

I think that the navigator can be removed from the game if somebody wanna play hardcore and mark his position on the Map :P
on bad weather and fogy day u are really lost at the sea if u play hardcore.




Last edited by Sjizzle; 05-05-2014 at 05:09 PM.
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Old 07-26-2013, 01:44 PM   #3
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Old 07-26-2013, 01:44 PM   #4
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Old 07-26-2013, 02:40 PM   #5
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Thanks Sjizzle

By the way, I have just found this:

http://www.allaboutsailing.co.uk/nav...osition-fixing

P.S: if you need for more reserved posts, I will happily delete this one
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Old 07-26-2013, 02:48 PM   #6
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thanks gap
no need to delete
now i am working on celestila fix position wich is a bit complicated ....
wich one need some math knowledge


Edit:
HO. 229 book

A very accurate method. It is produced in a six volume series. This course uses volume 3. The tables are used with the Nautical Almanac to obtain elements necessary to obtain position at sea. It is a straight forward method and requires no mathematical calculation beyond addition and subtraction of degrees and minutes and decimals of minutes. A popular method.


idk if they have it in WW II
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Old 07-26-2013, 03:03 PM   #7
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Quote:
Originally Posted by Sjizzle View Post
..idk if they have it in WW II
I'm sure they had it.. they had it since 1767 AD..
look here - http://en.wikipedia.org/wiki/Nautical_almanac

Thanks for this great work.. I think it's time to me to learn it finally ..
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Old 07-26-2013, 03:21 PM   #8
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136 pages only with tables

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Old 07-26-2013, 03:31 PM   #9
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Quote:
Originally Posted by Sjizzle View Post
HO. 229 book

idk if they have it in WW II
I am afraid not

According to the following link, the particular nautical almanac that you are talking about was published sometime between 60's and 80's:

http://fer3.com/arc/m2.aspx/HO-22924...ar-2011-g15994
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Old 07-26-2013, 04:21 PM   #10
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Some useful navigation resources:

http://www.offshoreblue.com/navigation/

P.S: most of the documents are in pdf format. If only we could open them in game... Unfortunately I think this topic has been commented by TDW already, and IIRC it is not possible
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Old 07-26-2013, 05:02 PM   #11
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Default How a Sextant Works

an informative short article about the workings of a sextant

http://www.tecepe.com.br/scripts/AlmanacPagesISAPI.dll

Sorry for hijacking the thread
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Old 07-27-2013, 12:33 PM   #12
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Quote:
Originally Posted by Sjizzle View Post
in this thread i will try to show u how to fix your position on the map without using the navigator From the game.

Frist Tutorial:

Coastal navigation running fix

Running fix needs also known time from 1st LOP to 2. LOP, steady course and steady speed to calculate your traveled distance and direction between 1. LOP and 2. LOP.
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Old 07-27-2013, 12:51 PM   #13
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Quote:
Originally Posted by LemonA View Post
Running fix needs also known time from 1st LOP to 2. LOP, steady course and steady speed to calculate your traveled distance and direction between 1. LOP and 2. LOP.
from allaboutsailing.co.uk, whose full address I have posted below (hope Sjizzle won't mind if I quote the whole paragraph here):

Quote:
Running Fix
The running fix (or transferred position line) is a method to determine your position if you only have 1 visual reference point (like a single lighthouse). The methodology is as follows;
  1. As you approach the single point, take a bearing on it with your hand held compass. Make a note of the log, and course being steered.
  2. Once there is an appreciable change in the angle to the object, take another bearing and note the new log reading.
  3. Plot the 1st bearing, and anywhere along this position line, make a mark and from this point, plot the course steered. Measure down this track the distance travelled (the difference between the 2 log reading). and make a second mark.
  4. Transfer your first position line, keeping it parallel, down to your second mark.
  5. Where this transferred line crosses the second compass bearing is your position.

Consider the accuracy of this method? How well was the course steered? How accurate is the log? Was there any tidal streams of leeway?
These can all be factored in to improve the fix, but generally, if the distance between the 2 bearings is not too large, it will be accurate enough.

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Old 07-30-2013, 02:01 PM   #14
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this is a good one
http://navsoft.com/Celestial_Navigation_Tutorial.pdf
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Old 07-30-2013, 02:03 PM   #15
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Quote:
Originally Posted by LemonA View Post
Running fix needs also known time from 1st LOP to 2. LOP, steady course and steady speed to calculate your traveled distance and direction between 1. LOP and 2. LOP.

A fix is called a running fix when one or more of the LOPs used to obtain it is an LOP advanced or retrieved over time. In order to get a fix the LOP must cross at an angle, the closer to 90° the better. This means the observations must have different azimuths. During the day, if only the Sun is visible, it is possible to get an LOP from the observation but not a fix as another LOP is needed. What may be done is take a first sight which yields one LOP and, some hours later, when the Sun's azimuth has changed substantially, take a second sight which yields a second LOP. Knowing the distance and course sailed in the interval, the first LOP can be advanced to its new position and the intersection with the second LOP yields a running fix.
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