Quick Query please
 

Could someone please briefly explain the meaning and significance of the yellow,orange and grey shapes which surround warships when in engagement situations.
I assume they must be related to sensors etc and their ranges but would appreciate a clear indication of the exact meaning of each display and the different significance of each colour.
Many thanks for any clarification...

Grey circle = visual range (From how far the enemy can see you)
Yellow circle = Hydrophone range (From how far the enemy can hear you)
Red circle = active sonar range (that PING thing, stay out of that area :O:)