Hi Taki
How you want to play the game is up to you whether being realistically or not.
You need to gain experience and understanding as you grow into the game before venturing into more difficult levels.
If you make the game too difficult without the experience you will give it up and look for something else.
You can use the charts if you find them useful but not the mod.
Post #96 R.P.M. Hydrophone How To Get The Contact's Speed
Peter