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Old 25-04-2016, 16:15   #1
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Sleep Science and Watch Keeping Schedules

Hi all, I was having a conversation with a friend of mine who is a sleep scientist about watch schedules during offshore passages. I know this issue has been discussed extensively and I am familiar with most of the most common schedules. Yet, this conversation made me wonder how much the standard schedules have been informed by sleep science.

Take for example the common “3 hours on 6 hours off” schedule often used by 3 person crews. This schedule correctly allows someone to sleep for 6 hours, thus benefiting from all sleep stages and waking up during REM (and refresh). Yet this schedule forces the cycle to shift every day, so that your circadian clock never settles. This apparently is a big “no-no” in sleep science. My friend said “if you want to really mess up with their schedules, keep shifting their sleep every day. Your clock never sets and you’ll get disrupted sleep every day. It’s like sleeping in a new place every night”. The 3 on 6 off plan sounds like a good idea because no one is "stuck" with the bad shift every day, but this shifting of schedules can create havoc with people's sleep quality. Apparently the science of shifting schedules suggests that doing so keeps people from getting to deep sleep and do not feel rested even after sleeping for 6-8 hours.

Apparently, the key, from a sleep science perspective, is to provide 1) consistency 2) ability to sleep uninterrupted no less than 4.5 hours in 1.5 hours increment, with 6 hours being optimal.

I looked at multiple watch schedules and did not find anything that provides such set up for a 3 person crew.

So I played with different options and came up with this for a 3-person crew: Three 5-hour shifts during the day starting at 0600 and three 3-hour shifts during the night starting at 2100. This allows for all crew members to experience 6 consecutive hours of sleep sometime during night hours and yet keep the night shifts manageable at 3 hours each. This is also a stable schedule that remains the same day after day which helps the crew’s circadian clock to “set” and thus facilitate restful sleep. The plan would look like this:



As you can see, every crew gets to sleep during the night for 6 hours. Crew 1 from midnight to 6, crew 2 from 3am to 9, and crew 3 from 2100 to 3am. Every crew also gets a long period of off time of 8 to 10 hours.

For those of you who have done offshore passages with 3-person crews, any thoughts on this schedule? Any major problems you see?

Thanks! bb.
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Old 25-04-2016, 16:23   #2
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pirate Re: Sleep Science and Watch Keeping Schedules

Looks good to me mate..
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Old 25-04-2016, 16:30   #3
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Re: Sleep Science and Watch Keeping Schedules

You'll need to fit cooking and cleanup chores into the schedule, as well. Don't forget the head, it wants a quick wipe down, as well.

Ten hours in a row off, not dedicated to any purpose is a looooong time.

Why do you want a third person, anyway? With 2 people, 6 on 6 off, loosely configured for a nap as part of the off watch periods works really well, rest-wise, and allows time for falling asleep for those who take about 45 min. to fall asleep.

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Old 25-04-2016, 16:46   #4
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pirate Re: Sleep Science and Watch Keeping Schedules

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Originally Posted by Ann T. Cate View Post
You'll need to fit cooking and cleanup chores into the schedule, as well.

The one coming off the last night watch (0300-0600) does B'fast, 1st night (2100-1159) watch does lunch and the morning watch (0600-1100) does supper

Don't forget the head, it wants a quick wipe down, as well.

Leave it as you find it.. CLEAN..

Ten hours in a row off, not dedicated to any purpose is a looooong time.

Not if'n youz a lazee booga..

Why do you want a third person, anyway? With 2 people, 6 on 6 off, loosely configured for a nap as part of the off watch periods works really well, rest-wise, and allows time for falling asleep for those who take about 45 min. to fall asleep.

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Old 25-04-2016, 16:54   #5
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Re: Sleep Science and Watch Keeping Schedules

three man crew... what's wrong with 4 on 8 off? Simple, repetitive and long enough sleep times.

Jim
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Old 25-04-2016, 16:58   #6
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Re: Sleep Science and Watch Keeping Schedules

Thanks Ann, yes the assumption is that all cleaning and cooking duties would be divided during the off hours. So the long off hours would not be fully off.


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Old 25-04-2016, 17:01   #7
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Re: Sleep Science and Watch Keeping Schedules

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three man crew... what's wrong with 4 on 8 off? Simple, repetitive and long enough sleep times.

Jim

I think that would work perfectly too.


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Old 25-04-2016, 18:39   #8
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Re: Sleep Science and Watch Keeping Schedules

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As you can see, every crew gets to sleep during the night for 6 hours. Crew 1 from midnight to 6, crew 2 from 3am to 9, and crew 3 from 2100 to 3am. Every crew also gets a long period of off time of 8 to 10 hours.

For those of you who have done offshore passages with 3-person crews, any thoughts on this schedule? Any major problems you see?

Thanks! bb.
I have routinely used something like this on longer passages with crew that can be split into three watches (3 or more).

Don't get hung up on sleeping during the night. The reason that short watches are often employed at night is to reduce operator error caused by fatigue during night watches.

The long off time during the day is for catching up on sleep.

After 3 to 5 days depending on the person you are in the cycle and generally get enough sleep, prior to that everybody sleeps almost every off watch moment (or at least is in their bunk)

The four on eight off works well in more benign conditions but in rough weather the four on can be a bit much for some.

Sailing with just my partner and myself we tend to slip into a three hour night watch schedule when the conditions are tough but when the sailing is easy we just split the night in half. The days are flexi and we each take a nap as we feel like it.

On the long nights if we find we can no longer stay awake we simply wake the other person.

On the subject of keeping a non shifting watch schedule or one where each watch is the same each day. That has definitely a 50/50 split among the human race I would say. I prefer to rotate so that I get to enjoy sunrises, sunsets, midday, midnight etc.. It can be boring to only have the middle night watch and one in the middle of the day for 30 days in row.

Other people swear by keeping to the same watch each day. Usually those that bag the watches for themselves that are most broadly similar to a normal day i.e. a late evening watch, sleeping from midnight to 8 am, etc... those people are not going to want to change I sailed with one skipper who always wanted precisely that routine.

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Old 25-04-2016, 19:13   #9
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Re: Sleep Science and Watch Keeping Schedules

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The four on eight off works well in more benign conditions but in rough weather the four on can be a bit much for some.
Thanks Chris, I was wondering about this issue. This makes my original idea a bit tricky to pull off in rough weather because the long 5h shifts during the day. Although there are easy ways to split or share the day shifts into smaller chunks without entering a shifting schedule (Although I know some like you like the shifting schedule) :-).
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Old 25-04-2016, 19:42   #10
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Re: Sleep Science and Watch Keeping Schedules

Nice post! I like what you say. My comments:

Are you in the North or South now? Are you sailing in the respective summer?

I ask as the tropical night tends to be 12 hours and given that we sleep better at night, I would move the sleep part of the scheme to start at sunset. (this would imply moving the scheme "up" by about two hours)

I like that you set the scheme so that the night watches overlap - it sure would help me to have someone to talk to on the night watch (quetly, of course).

My other idea is that from the three onboard you can tell (from observation or by asking your crew) who a sparrow is and who an owl is ..., then assign them the night watches that fit their natural sleep preferences best. No help if you have three owls onboard though! ;-)

Thank you for this very interesting thread. If you apply your science to real life sailing, perhaps you can find time to come back to this thread after the season and post your findings from the field?

Cheers,
b.
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Old 25-04-2016, 20:31   #11
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Re: Sleep Science and Watch Keeping Schedules

I like it. Splitting the day into 5 hours shifts is clever. I hate revolving watches. I much prefer the routine of a fixed shedual, but thats me, and some swear by rotating it so it different each night. 3 hours is all I want to do at night. I hate 4 on 8 off, it gets so repetitive and the night time watches get so long if its cold and you are tired.

I actually use, and quite like 2 on 4 off for cold weather but the sleep period is a touch short. Prehaps a inverted version of this would work with 2.5 on 5 off at night and 3 on 6 off during the day. Got to try playing with it.

Its also worth trying to adhere to the IMO requirements of 10 hrs off in two blocks with at least one being 6 hrs, that way you can argue in an incident that your fatigue management was as per recomended.

I usually also schedule in duties, ie dinner, lunch etc and who is on call if needed.

With 4 people I do two things, either have a floater (ie capt on call) and run a three watch system. Or I pair up and run a two watch system and run the watches as either single or double depending on fatigue and conditions.

Thanks for posting the watch bill. I think its a good one.


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Old 25-04-2016, 21:08   #12
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Re: Sleep Science and Watch Keeping Schedules

As captain, I find it very difficult to sleep more than 2-3 hours at a stretch unless its very mild. I have some type of built in gyro that only dampens for that amount of time.

You guys really sleep 6 or 8 hours solid offshore? Not since I was 17.
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Old 25-04-2016, 21:41   #13
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Re: Sleep Science and Watch Keeping Schedules

I found out decades ago that if I can sleep a couple of hours between midnight and dawn with a power nap when needed, that I stay in fair shape for over a month.

My longest run was 90 days but I was all out of sweet by the end of the trip.

As I age and lose more P&V , I find I need to kick back for a couple of days and recoup afterwards.
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Old 25-04-2016, 22:00   #14
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Re: Sleep Science and Watch Keeping Schedules

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You guys really sleep 6 or 8 hours solid offshore? Not since I was 17.
If conditions are good and I trust my crew I can happily sleep till the cows come home...
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Old 25-04-2016, 22:42   #15
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Re: Sleep Science and Watch Keeping Schedules

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Thanks Chris, I was wondering about this issue. This makes my original idea a bit tricky to pull off in rough weather because the long 5h shifts during the day. Although there are easy ways to split or share the day shifts into smaller chunks without entering a shifting schedule (Although I know some like you like the shifting schedule) :-).
I was referring to night watches really. But yes in rough weather you have to monitor people, and yourself, very closely. As Ben suggested be prepared to drop down to 2-hour watches and I have heard of people dropping down to steering stints of 30 minutes or so.

I think you have to get away from the idea that night is for sleeping. All off watch time is for sleeping if desired although in the tropics I have found that sleeping after mid morning is more a case of laying on your bunk and sweating

The purpose of any watchkeeping system is to keep everybody fit, well and alert for those time when the excrement hits the turbine and then it becomes a loose template at best.

Please don't take these comments as criticism because as I said at the beginning my first response what you have posted is more or less what I use on crewed trips these days. It will work fine

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