China would probably have had only a "brown-water navy", with limited blue-water assets.
And how did they manage to invade Alaska then ?
They must have had a very sizable blue water navy.
As for Rivet City, we dont know the story of the carrier yet. In the game , the carrier was modeled after the USS Oriskany, a Essix class aircraft carrier which was mothballed in 1976 and stayed moored in Washington until 2004 when she was sunk to become a artificial reef.
So its quite possible that Rivet City actually IS the Oriskany and was just a museum piece that was kept until 2077 and had nothing to do with the war.
Thats the real Oriskany
[img]http://upload.wikimedia.org/wikipedia/en/thumb/1/15/ExUSSOriskanyLeavesPort.jpg/800px-ExUSSOriskanyLeavesPort.jpg[/img]
And her fate of 2004
[img]http://upload.wikimedia.org/wikipedia/commons/e/e9/USS_Oriskany_sinking.jpg[/img]