Coordinates
 

I sometimes receive radio message with the position of other ships. First are they ennemies or allies ? Second, how can i know their position since there is no coordinates marking on the map ?

If you are playing with GWX, most of that radio traffic is just atmosphere to help set the mood and make you feel less like the only U-Boat fighting the war.

Use the ruler from the Greenwich meridian and equator. Each degree is 120km long. Grab a calculator and divide the minutes of latitude (longitude) by 60, add the number of degrees (of the same) to the resulting fraction, then multiply by 120 km.

But as said, you probably won't find anything there, unless it happens to be part of the scripting layer.