The engines work, the fathometer is down

Michael tells Desmond that the engines should be working and Desmond runs to tell Hendricks, the helmsman. The engines fire up and they dial in the bearing, 305, but but there is something causing interference on the fathometer and they can't see the reef. He says it's coming from the boat and Desmond runs off to find it and shut it off. Hendricks also says that he won't get any closer to the island that 5 miles without the fathometer.

It's not important but as Desmond's running out, there's a "how to wear a life preserver" poster next to the door. I just thought it was funny.