This video is kind of long so I'll get you right to the significant stuff.
Vehicles are secured to the decks via hooks and straps.
http://www.youtube.com/watch?feature=pl ... YWZs#t=53s
1/2 hour into the trip the weather starts to turn and the water gets... umm, choppy?
http://www.youtube.com/watch?feature=pl ... YWZs#t=93s
A sister ship crossing paths with this one gives perspective how high the seas were.
http://www.youtube.com/watch?feature=pl ... WZs#t=188s
The aftermath.
http://www.youtube.com/watch?feature=pl ... WZs#t=284s
Damn!!!!! Every single truck, van, car, etc. looks like it got at least some damage. And those RV's that got squished between the semi's...
