Hey,
There's a bit more to timekeeping than was noted in the linked article. The idea of using a half-hour glass is linked in turn to the idea that the nautical day changes at noon, vice midnight as we know today. This is because the nautical day starts with the Noon sight, taken with the sextant/octant/astrolabe to establish the current ship's latitude. At the moment of "local apparent noon" (LAN), the glass is turned for the first time of the day, and the chip log (speedometer) is hove. At 1230, the process is repeated, and the ship's bell is struck once (it was a flogging offense to miss "turning the glass" exactly as the last grains of sand ran out, thus throwing off the accuracy of the timekeeping). Every half-hour after that, the bell is struck once more cumulative (i.e., two bells at 1300, three at 1330, etc.) BUT, the bells are struck in twos for each hour, and once for each half hour (i.e., three bells are struck as ding-ding, pause, ding) an so on until eight bells at 1600. The whole process, less the sun sight, is started over for each 4-hour watch.
Each watch had a distinctive name as well. The "first watch" was the Afternoon Watch, the next, the Evening Watch (broken into the First and Second "Dog Watch" 1600-1800 and 1800-2000), the "Third" or Night Watch (hence the name of the TV series) 2000-2400, the Midnight, or Mid Watch from 0000-0400, the Morning Watch from 0400-0800, and finally the Forenoon Watch from 0800-1200. So, to express the time in traditional sailor talk, 1530 would be "Seven Bells in the Afternoon Watch"; 0930 would be "Three bells in the Forenoon Watch", etc. you can have a lot of fun with officers by expressing time this way; it irritates them to no end, and establishes you as a traditional "old salt" of sorts. There are related articles on our website:
http://tmlha.exis.netRegards,
Allen Mordica, STCWO4, USCG (ret)
Tidewater Maritime Living History Assn. (TMLHA)
