At least you'd have a genuine refuge for most of your time, and you'd only encounter zombies when you were fully prepared for it. That's miles ahead of anything we've seen in either Dawn of the Dead or the Walking Dead.
Plus acquiring food and water (assuming they could get their hands on a few desalination devices) would limit how often they'd have to dock. They also wouldn't have to worry about wasting any more ammunition then they'd have to, such as when waking up in the middle of the night when a herd of zombies just happen to be wandering by.
It's not like there's been any evidence that the virus has spread to any animals or anything. So fishing would be perfectly viable, and extremely plentiful now that all the commercial fishing is no longer an issue.