Can confirm, weird things happen after you spend a lot of time underway. I did 4 years on submarines and you start to see and hear things in the sealed boat after a few months at sea. Its like the ghosts of sailor past are coming up from the depths to haunt you. Shadows going around the corner in a room thats empty, knocking sounds from the hull. It can really get to you after a while and the only thing you can do is bear it. Im not the only one whos seen and heard things on my boat either. Keep your wits about you and try to maintain your sanity if you can.