boat we hear the sea depth given as "310  meters"; thats equivalent to 170 fathoms or 1,020 feet. We then  hear the same depth given on board the destroyer as "150 fathoms".  Murrell converts it in his head first to meters, then to feet, even  though as an experienced American seaman he would certainly know  that 1 fathom is exactly 6 feet. Furthermore, although the fathom  depth was wrong, he converts to the right value: "310 meters 