180516-N-UG095-051 SAN DIEGO (May 16, 2018) Machinist’s Mate 2nd Class Chester Rosal, assigned to amphibious assault ship USS Boxer (LHD 4), explains the purpose of main control to nuclear propulsion officer candidate educators during a tour of the ship’s forward main machinery room. Boxer is pierside in its homeport preparing for sea trials. (U.S. Navy photo by Mass Communication Specialist 2nd Class Michael Eckelbecker/Released)