why there is a need of maritime communication?

Answer 1

I will give you a good example of why there is a need for maritime communications.
On a recent return to the state from a run over to the middle east and India we discover a small box with duct tape and a wire hanging out of it. Phone calls, email, and pictures were made to the authorities in the states. Arrangements were made to have the a bomb team meet us off the coast. They took the box off the ship and we proceeded into port.
None of that would have been possible without maritime communications.

Answer 2

For safety. It is needed to eliminate maritime collisions, and prevent loss at sea.

Communication is needed to enter into ports and to cross international boundaries.

Answer 3

So that ships at sea can communicate with each other and with the land. Cellphones generally tend not to work too well at sea as there's no relays. Without boosters and relays a cell phone cannot work and you don't have them in the middle of the Ocean.