I'd love to think I'd be calm and collected, but I think the reality would depend on the circumstances. Big difference once the ship started listing to one side. I know I would be wondering if it was going to turn upside down. Plus what if that's where my lifeboat was. Something else that would make me nervous would be if I was seperated from family.
I think in most cases that's where people start to panic. On the other hand, I think that's where hero's are born. Some people always seem to rise to the occasion. Just not the captain of that ship.