a traditional way to mourn the death of a sailor, whether lost
at sea or not, is the ringing of eight bells. In the standard watchkeeping system, where a bell was rung every half hour, eight bells meant the end of watch.
If you've never heard it, the bells are rung in groups of two. Five bells, for example, two and a half hours into the watch, would be rung: bong bong--pause--bong bong--pause--bong. So eight bells would be rung in four sets of double rings.