I'm beginning to suspect that the Admiral is a ghost. That would certainly explain why we never see him, but only hear his disembodied voice. Most of the crew could be ghosts, too. Ghosts who keep the bits of the ship we can't see running at ship-shape.

Although...I honestly can't think of a single soul who, while alive, was interested in looking at people without their trousers. [Because Bertie leads a VERY SHELTERED LIFE.] So I can't imagine why a ghost would.