Why 18-hour schedule on submarines?

December 7, 2012 12:59 AM

Why do US Navy submarines operate on 18-hour schedules, with 6 hours on watch and 12 hours off? How did this start? Is there independent justification, or is this some hold-over from old traditions? Why did someone think this was a good idea?
posted by cthuljew to Law & Government (4 answers total)

Best answer: There is a whole book on this from 1996.

From the book: "The 6-on/12-off schedule is operationally valuable because it allows 24 hour coverage with only 3 watches. This is required by the space limitations on submarines. The schedule also limits the duration of each watch to 6hr. The shorter watches are considered necessary to assure maintenance of alertness during sometimes monotonous work performed at all hours of the day."

The book also explains why a lack of 24 hour phasing was not considered an issue at the time: no natural light on submarines and no weekends/days off for crew members to adapt to their biological clock.

According this article, the 18 hour schedule was introduced in the 60s. Before that, apparently, a 4 hour on/8 hour off schedule was the norm.

"Since the 13th century, maritime workers have utilized a 4 hours on, 8 hours off (4/8) watch schedule that continued into the Polaris submarine patrols of the early 1960s. However, because modern Submariners must also train, qualify, and conduct drills when not on watch, the 4/8 schedule prevented them from obtaining sufficient sleep during their off-watch periods. During prolonged patrols, Submariners suffered from progressive sleep debt. To remedy this, the 6 hours on, 12 hours off (6/12) schedule was adopted."
posted by MuffinMan at 1:26 AM on December 7, 2012 [7 favorites]

Response by poster: I kept seeing this paper pop up in my searches, but couldn't find a link to the actual content, so thanks a lot for that! I also saw the second article you linked, although it didn't explain what I was hoping to learn. And the study it talks about seems to be arguing, and it makes sense to me, that having a 24hr cycle with 8 hours on watch would be just as effective. Myself being a full time overnight worker, I find that an eight hour shift after a full night of sleep is much easier than any shift after less than eight hours of sleep.
posted by cthuljew at 1:41 AM on December 7, 2012

cthuljew: "And the study it talks about seems to be arguing, and it makes sense to me, that having a 24hr cycle with 8 hours on watch would be just as effective. Myself being a full time overnight worker, I find that an eight hour shift after a full night of sleep is much easier than any shift after less than eight hours of sleep."

As someone who has done it, 6 hours is PLENTY of time on watch for the kinds of watches that are on submarines; it is incredibly boring. you are required to sit at your station (although some watches are 'roving') and monitor whatever it is that you are supposed to be monitoring. whether that's the Reactor Control Panel, or the Control Planes. You make adjustments to the operation of equipment, and take logs. that is it. Any maintenance or calibration that equipment might need has to be done by someone not on watch. Typically that was done by the 'offgoing' shift; the one that had watch previously, had their meal, and are in their 12-hour 'off' time. you do whatever work you are scheduled, which didn't normally take 6 hours and then go to bed. Some days that 'off' time was interrupted by things like casualty drills, training, and once a week whole-ship cleaning (field day).

4/8 schedule is still pretty normal when in port.
posted by ArgentCorvid at 5:24 AM on December 7, 2012 [6 favorites]

For future readers: related Metafilter post.
posted by Chrysostom at 10:11 AM on December 7, 2012 [1 favorite]