TUTORIALS

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How to give your position by using the german grid code

The world is divided in rectangles named with 2 letters. Each rectangle is divided in 81 quadrants. And each quadrant is divided in 81 small squares. To give your position, you have to give the letters of the rectangle, the digits of the quadrant, and the digits of the small square where you are. A quadrant is divided in squares which have exactly the same digits as the quadrants have in a rectangle. Thus, on the graphic below, the location is : AE 5615.



On your navigation map, you won't find the digits for the squares in a quadrant. In order to determine them, you have to use my GridXXXX mod (contained in the Alberich mod). First, select the proper scale : 125 km. Then, drag the grids from the upper side, and place the correct grid on your current quadrant. Then, read the digits of your square. On the picture below, it is EJ 1563. If I was in the square marked "60", it would be EJ 1565, and not EJ 1560 !


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2. How to plot an interception course

You need to know :

- the ennemy course and speed (T)
- your position relative to the ennemy
- some basic mathematical skills


a. THEORY

Your interception course will depend on your speed (S). Indeed, by dividing S by T : S/T = x, that means that you will travel a distance x time bigger than your ennemy. When intercepting him, that also means that he has travelled I kilometers, while you have travelled J = x.I kilometers, x depending on your speed. That's fundamental.



Now, how to determine your course ?

Let's remember the Thales' theorem, also known as the Intercept theorem : 2 triangles which have their edges parallel, are similar (their respective edges are proportional). Example : ABC is similar to AXY, and AB/AX = AC/AY = BC/XY.



This will allow you to find your interception course without to know where you will intercept the target. How ?

First by drawing a small triangle, proportional to the real one that you don't know for yet : i is a fictive distance travelled by the ennemy, after which he will find you on his route. From this fictive interception point, draw j (which is the distance travelled by you, so j = x.i) by drawing a circle with a radius equal to j, and which cuts the line which links you to the ennemy (K) : you found the 2 other edges of the triangle.



Now, just draw a line from your submarine and parallel to j. According to the theorem, i/I = j/J, so j/i = J/I = x. So, this line will cut the ennemy route at the interception point, found with the speed S that you have chosen !


b. PRACTICE

- Draw the ennemy course (blue line)
- Draw K (grey line)
- Draw a line from the ennemy and following his course, equal to i (if T = 10kts, then choose i = 10 km)
- Draw a circle from the end of i, which a radius equal to j (if you have chosen S = 14kts, then j = 14 km)
- Draw the angle (black) between j and K
- Draw the same angle (red) from your submarine : you find the interception point.

Note : you can choose whatever values for j and i, but j/i must equal S/T = x, that means j/S = i/T = whatever value you want (we chose 1 for our example : 10 kilometers for 10 knots, 14 km for 14 kts).
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3. How to calculate the distance travelled by a ship (in kilometers) which has a speed given in knots ?

One knot = one nautical mile per hour.
One nautical mile = 1 852 meters, or 1,852 kilometers.

So 1 kt = 1,852 km/h.

So Distance (km) = speed (kts) x 1,852 x time (h)
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4. How to calculate time (t) and distance (d1) to join a ship when you are behind or in front of her ?


A. When you are behind.



Distance travelled by the submarine : d1 = v1.t = d2 + D

So : v1.t = v2.t + D so t = D / (v1 - v2) and d1 = v1 . D / (v1 - v2)


B. When you are in front of.



Distance travelled by the submarine : d1 = v1.t = D - d2

So : v1.t = D - v2.t so t = D / (v1 + v2) and d1 = v1 . D / (v1 + v2)
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5. How to change time compression maximum values ?

In this game, you will have to shadow convoys, sometimes during several days. To allow you to do so without having a game stuck on TC = 8, here is the procedure :

- Close your game
- Go in My Documents\SH3\data\cfg
- Open main.cfg
- Change the following value :

[TIME COMPRESSION]
... HunterState=256

- Save the file
- Now, you can play the game !
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