Other mistake: In the scene in the engine room, a steam pipe bursts and sprays hot steam (you can see the rising mist) on the handle of the door to the propeller shaft. After the steam has been off, Borgnine then grabs it with abandon. It should have burned his hand.
Other mistake: There was no way the dining room could have filled up with that much water in that amount of time.
Other mistake: In the scenes bookending the underwater swim, there is no way to figure out how both pools of water are set up. Sometimes a cast member jumps in and appears to be standing in 3 feet of water and other times cast members dive in as though the water is 25 feet deep. In fact, the whole underwater scene makes no sense at all. Cast members swim up meaning they're going through a hatch in the ceiling or floor, there are railings attached willy-nilly and there appears to be no regular doors anywhere.
Answer: He's the representative of the owner of the ship.