[antiunion person]

Not that I'm an expert about weapons by any means, but I don't think an rpg has enough power to blow through the steel hull of an oil tanker. A cruise liner, I imagine would have the same thickness of hull as a oil hauler. Maybe a naval person can answer this question. I know no ship is unsinkable but if the water tight doors/hatches are sealed and a flooding compartment sealed off, wouldn't that keep a ship from going down?? If it's hit multiple times, it will probably sink, but only one hit, I don't think it will.
But the comment about Bush being blamed about a ship being sunk, hell yes, they will blame him. I'm supposed the media and Obama Osama the non thinker is not already blaming the Bush administration for the swine flu breakout in Mexico.

[El Gato]

but I don't think an rpg has enough power to blow through the steel hull of an oil tanker.

An RPG, with a HEAT warhead, can penetrate up to 600mm of rolled steel armor. I don't think that ships are built of anything that thick. (600 mm ~= 23.6 inches). They don't make an especially large hole however. I don't know what the standoff distance to the inner hull on a tanker might be, but I suspect it's sufficient that the jet from the HEAT warhead would not penetrate the second hull, but I could be wrong about that.