A Japanese ship was en-route to the open sea. The ships captain, sweaty and dirty, decided to take a nice cold shower,before they hit the massive waves. He undressed, and takes off his wedding ring and places it  in the table.

He in the shower for four minutes, and when he comes out, his ring is gone. Then interrogates the crew to make make sure he got his ring back.

The cook:  I was preparing lunch.

The engineer: I was in the engine room.

The first mate: I was correcting the flag, because it was upside down.

The Navigation Officer: I was sleeping in my cabin.

The radio Officer: I was sending out messages to the company, saying that we are alright.

He immediately caught the thief.

Who was thief?