Complex sentence: There is only one COB on a submarine or Coastal Patrol Ship and he is generally responsible for the day-to-day operations of the non-nuclear portion of the boat, and the morale and the training of the boat's enlisted personnel.
Split into simpler sentences: There is only one COB on a submarine or Coastal Patrol Ship. The COB is generally responsible for the day-to-day operations of the non-nuclear portion of the boat as well as the morale and training of the boat's enlisted personnel.