Here's a link to a study that was done using 90 officers in bridge, engineering & cargo simulators "to assess the impact of fatigue in realistic seagoing scenarios":
The study's authors have come up with a toolkit - a Fatigue Risk Management System for seafarers. The article linked above doesn't go into any detail about the study's results; they're to be published in the March issue of Tanker Operator Magazine:
So this particular blog post won't give you any information to go on right now, though you can read the article next month. But it raises the question: what do you consider a good watch rotation?
I've worked under a number of different systems - to wit:
- The traditional seagoing three-watch system of 4-on, 8-off;
- The tug-standard two-watch system of 6 & 6;
- And more recently, an experimental harbor tug two-watch system of 8-on, 4-off, 4-on, 8-off (it consisted of the Captain standing 0800-1600, the Mate 1600-2000, Captain 2000-2400, and the Mate 0000-0800). With regard to this last one, I've heard of a similar system that ran 7-on, 5-off, 5-on, 7-off. Same idea. I think I'd prefer the 8-4 over the 7-5, just because it would give you a better uninterrupted sleep time - which is the whole point.
On tugs operating strictly in harbor, I've also divided the 24 hours with the Mate into "two big chunks" - with me standing 0800-2400, leaving the Mate the night watch from 0000-0800. That's a long graveyard turn, but he gets the whole day off to sleep as long as he wants, cook, etc. And I've done this rotation as Mate, too.
That might sound tough, and in an extremely busy environment it could be. But harbor work seems to come in rushes, with time in between busy spells to rest or eat. Also, in harbor work you may have a busy day with just a few jobs at night. In Baltimore Harbor, we used to consider a night with four jobs or more for our tug a long night. So the Mate sometimes could grab a catnap during his night watch.
When I was Mate, and studying for my Pilot's license, I enjoyed working under that "two-big-chunks" system; on slow nights I'd study my chart so the time passed quickly, and then I had all day to rest up and do additional study. My liking for it as Mate led me to institute that system when I became Captain, so long as the Mate I had agreed to work that way. They didn't all like it, and if they didn't we'd work 6&6. As for the Captain's long day watch - as I say, harbor work comes in bunches with breaks in between, so it wasn't solid work; and I'd be up all day anyhow, might as well be working! It never bothered me.
Please comment with your own experiences, and the pros & cons of the systems you've worked under. This is a topic that will be getting more regulatory attention as flag states and the IMO attempt to address mariners' fatigue issues; even the deep-sea 4-on, 8-off system, which I've done for many months at a time without strain, can be stressful if you're on short runs with a lot of docking and cargo evolutions. So let us know what you think!