What's wrong with writing poetry on an aircraft carrier? I can't speak to being on an aircraft carrier, but on a submarine you are not in war mode 24/7; there's time to do ordinary things. (usually).
Let me guess: Tommy here hasn't ever served in the military, right? All he knows about it is from movies?
I wouldn't say 90% but it is significant. "Hurry up and wait" is a common phrase in the military - you don't exactly have much "free time" (where you could do as you please) but you do have a lot of time wasted because you have to be at this location at 5:30 so you can wait for an evolution at 6 that doesn't actually involve you doing anything until 7:30. So you just sit around waiting to do shit but can't go anywhere else. Poetry sounds like a better way to pass the time than what I did in those situations, which was usually nap or BS with the others waiting around.