Added the periscope sighted/sub sighted to the radio messages. There is a new user option that specifies the maximum distance a ship can have any chance of sending a radio message saying they detected you. Default value is 8000m.
I have compiled over 100+ ship names from WWII that the mod can use as the ship name.
The mod 'rolls the dice' when you are within that range and if you are spotted a radio message goes out from ship. If you are not spotted a random amount of time is assigned before the ship can 'look' for you again. The chance that it can spot you surfaced is 70%. The chance that it can spot your periscope is 35%.
Now I took this one step further

I also go through ALL the ship contacts in game and 'roll the dice' with them to see if they spotted a sub/periscope whereever they are. If so, they fire off a radio message

The percent chance that one of these contacts will spot a submarine is 5%.
What I'm not sure of is what to put in the From line of the radio message. Currently I just have the ship's name that sent it:
Next is to add radio messages for sinking/destroyed ships