Think we live in a civilized world?
These are not you run of the mill ghetto rats, so don't assume the slums would be your biggest concern if and when all Hell breaks lose, it will be your neighbors you need to keep a close eye on.

Food supplies are said to be running low, with passengers forced to queue for hours for cold onion and cucumber sandwiches, and there are also reports of fights breaking out as groups of “savages” fight over the dwindling supplies.
http://www.independent.co.uk/news/world/americas/cruise-hell-sewage-running-down-walls-and-savages-fighting-over-dwindling-food-supplies-8492863.html

Where do you find these?  I am starting to think you have a fetish for the worst in humanity.   

This actually would make for a good thought experiment, or a baseline in general.  These folks are scared enough to panic, enough to follow an authorative leader who could produce quick results.  Also important is the ability to also plan for long term. . .

I love human nature oddities, even the most civilized among us will slit your throat if it comes down to survival.

I no longer trust Govt, especially under a Marxists rule, so if shit hits the fan, I want to know what to expect and learn from every situation like this that arises.
One thing all these situations have in common, is a lack of leadership, it always seems to start with one out of control idiot, a panicked fool starts the stampede so to speak, and the crowd, not wanting to be last, always jumps in.

The one lesson to take from this is setup a chain of command early, people like structure, they want to know everyone agrees on a plan of action and everyone Must participate.
Mob rule will always win, so organize the mob early on.

Nonsense! We'll just ostracize those who refuse to play by the rules! That'll restore order!

Well played!!!

There was a Chain of Command, The Captain should have kept control. There is no way to tell what the issues really are until they dock. Some people suffer from the "Mountain out of a molehill " perception and spread grief.

Well played!!!

Yawn beat me to it.

A perfect example of a volunteer society with no government.