Taking over a ferry on the Seattle-Bremerton run is an excellent method for taking out one of our aircraft carriers. The Bremerton Naval Shipyards are just a short distance from the Bremerton Ferry Dock.
Terrorists could load a semi with a huge truck bomb. By timing their arrival at the Seattle Ferry Terminal, they could assure that they would be loaded to the front of the ferry, and semis are loaded in the center lanes of the ferry. As neither individuals or vehicles are searched when boarding the ferry, it would be no problem to put heavily armed terrorists on board. If they seized control of the ferry as it neared Bremerton, they could steer it down the inlet to where the carriers dock. The carrier would have insufficient time to react, and would not likely fire on a ferry full of passengers anyway. A semi-sized truck bomb, exploded as the ferry rammed the carrier might not sink it, but would certainly damage it, and would be the type coup that al Queda loves.
Sounds to me like a waste of a good bomb, but I guess it's possible.
How big are these ferrys? 100 people? 1000 people?
If they are big enough, they could sieze 3 or 4 ferrys at once and have as big an event as 9-11.
Would the National Guard Jets bomb a ferry full of civilians, in order to keep it away from an aircraft carrier, while news helicopters hovered over head? It would certainly make for some dramatic footage. Just what Al Quaida would like.