Satellite support is not just used for navigation, it is also used for detection and safe communication. And more over, it is a part of network centric warfare. If hovering above arabian sea, it can take pictures of karachi and your assets and what is being loaded on your vessels, where as your Naval communication is always at brick of being heard from anywhere. That's the difference.
A naval satellite can tell you, when to attack, and when the seas will favor you through meteorological calculations, more precisely.
It increases the range of awacs, by more than 1000kms.
That's network centric warfare.