Well, the first thing you need is bedding. chickens make shit. And unless you are terraforming your boat, you need to have something that absorbs that shit, and the smell, which can be removed and replaced.
Pine tree boughs seem to work well for this. (yes, old christmas trees) They absorb the shit and the odor.
Chickens are dumb... so, they will probably stay on deck right up until the time they want to jump overboard for reasons one can only assume to be an attempt at drowning.
With so little area, do not get a rooster. But two hens in a small cage will probably work ok.
Haha, yea ive kept them before but on land. I reckon my boats a tad small and the smell would be a bit much. A portable pen bankside when we're stationary would work though. Nomadic hens eh?!
That was hillarious!