solarz
Brigadier
My understanding of China's use of the nine dotted line maps are that they claim all the islands in the dotted line, not the ocean. Since the 1982 Law of the Sea, which China has ratified, you cannot claim ocean as territory beyond 12 nautical miles from shore. So if you want to know what ocean China is claiming, draw little circles around every island that is above water at high tide and large enough to support economic activity with a 12nm radius. You will find those are very tiny circles in the grand scheme of the South China Sea. Even in these territorial waters, the UN Law of the Sea still guarantees the right of innocent passage! There is no justified fear of restricted freedom of navigation should China control all the islands in the South China Sea.
A good parallel is how Greece treats the Aagean Sea directly East of the Greek mainland. The Aegean sea is full of islands, but much denser than the South China Sea. Greece controls every one of them, and thus the entire Aegean Sea is Greek territorial waters. But Greece still allows commercial and military ships to pass through the sea without a problem.
Of course, it's never been about free passage. It's always been about the exclusive right to the natural resources found in the EEZ.