I still think they should steal my idea.
It's kind of a waterworld (minus the suckiness) with Zombies.
Think about it. After the world is infected, what happens to all the people that are oceanbound? The virus has such a rapid incubation rate that it would most likely not spread to those out to sea during the 'event'. Unless a sick person was let onto a ship (why would that happen?) they are in the clear.
Now mankind must survive by retaking the land by force. A nice aircraft carrier would be very effective...
They have an abundant supply of energy (nuclear). All they need is raiding parties to resupply food and other perishables every so often. Eventually they will need to secure some land to plant crops to ensure a future food supply.
Hopefully there are some womenz on the ships, or else this might turn into a gay flick as the sailors try to propagate the species...