Question

why the sea along the eastern coasts is unsuitable for harbours?

Answer 1

Harbours act as better anchorage if the waterbody is surrounded by more than one sided landmass at the coast. Western India has much more indentations and creeks as compared to the eastern part and hence it becomes easier to load and unload to and from the ships. Moreover Western coast has deeper water at its continental shelf compared to the eastern coast, which again allows big and heavy ships to move closer to the main land.