Saturday, March 26, 2011

Fatigue... of the human variety

Watch Bill- 2 on 4 off
I have spent quite a large portion of my life on watch systems of one sort or another, and in general I dislike them all... No matter how clever the watch system is someone still has to be up and alert at 0300, and the human body (at least mine anyway) is just not designed for this kind of abuse... I struggle to keep my eyes open and mind alert, and I know I am along way from my peak efficiency (and it's pretty low even on the rare occasion that it reaches peak..)

I suppose there is one system I do quite like, It's a watch system where someone else always gets the graveyard shift, and I get to sleep. But that's not really very fair is it...

Those graveyard shifts are just bearable if I have had plenty of sleep, and are into the swing of a watchkeeping routine. If I am already sleep deprived and fatigued it is a dangerous combination that I do my best to avoid. I have already talked about Rolf and Deborah's excellent  Sleep bank concept where you make sure you have enough sleep stored up to keep you safe. Go to far into debt and the debt collectors will soon be calling. and then you will pay the price - with interest...

I always remember my father in a sleep deprived state when I was very young. We were sailing up the east coast of NZ and for whatever reason he had been awake to far to long. He couldn't correlate the chart to what he was seeing outside and so took the always reasonable approach and decided the chart was wrong and he had found some new islands... Fortunately Mum still had her marbles, and could navigate us home.

After a decent sleep my old man couldn't believe how stupid he had been (and still denies it..) but the scary thing is, abit like being very drunk, you don't know how impaired you are at the time, and to you your decisions seem rational and smart. Hallucinations are the extreme symptom of sleep deprivation. I have never got to that point, and intend never to (touch wood). But some stories of hallucinations by singlehanded sailors who have mismanaged their sleep are downright scary... Sleep deprivation is probably the root cause of a significant proportion of serious accidents at sea.

If you are alone you need to be particularly careful, to the extent that managing sleep becomes your number one priority. During my singlehanded Tasman crossing in Reiger I was lucky that the cheap alarm clock I had bought from a two dollar store (predictably) died on the second night. So I ended up sleeping at night with no alarms set. and I found that I woke up naturally every time I needed to, if the wind shifted slightly I woke up, If it dropped I woke up, and once I even woke up to see a ship 5 miles away (not on a collision course...) I think the sound of the engine and propeller woke me... It worked for me because I was well rested. If I was sleep deprived my body would not wake up for the slightest sound. I don't think I would recommend this anywhere with more traffic than the Tasman? Around the coast I kept a 20 minute look out with micro sleeps, a punishing routine - that I could only keep up for one night (anybody got any tips on this?). I guess the point here is that I made a decision that mid ocean my biggest risk factor was fatigue due to lack of sleep, rather than being run down...

With crew it is more about making sure everybody is getting enough rest. If crew decide to skip a sleep period because the weather is nice or they are reading a good book it can cause problems latter when they fall asleep on the graveyard shift. This often happens when you first leave port for a big voyage or race, most crew want to be up for the excitement or because they want to be hero's, I normally go for an afternoon nap and they think I am soft. But at 3oclock in the morning I am capable of making sensible decisions and they are struggling to keep awake... Even if I don't actually sleep in my afternoon nap, just lying down and relaxing does alot of good.

I keep away from caffeine when I am on watches. For me It can really effect my sleep patterns, but it is good to have as a backup if I really need to stay awake for 6 hours or so.

I hate the 4 on 8 off watch system, If prefer 2 on 4 off or 3 on 6 off. With only two I quite like 3on three off at night and 6 on 6 off during the day. But it is hard to get much agreement on this... watch systems deserve their own post later.

When sailing through heavy ice getting enough sleep as skipper is a huge problem, on Snow Petrel I should have stepped out of the watch system when we were in the pack ice, and been on call. I got very tired and it could have been dangerous if we had any problems. I drew too heavily from the sleep bank...

As a Skipper you need to look after your own sleep, don't be a hero, It's easy to overwork and overworry and micromanage everything and before you know it you are the one making stupid decisions, or crew take things into their own hands and "let you sleep" for a while, instead of calling you if and when they should. There is alotwatch and give crew a break as a treat... As a skipper it is good to be able to Nana nap, even just for 15 minutes can be refreshing.

On the ships we always write up night orders, with specific instructions for the officer of the watch (OOW), they must be read and signed  (and then followed..). I have used this system on yachts as well. It has many benefits, not in the least being that instructions aren't subject to chinese whispers, and are less likely to be  modified or forgotten at 3am. The night orders apply to that night only and can go in the logbook. The masters standing orders are more generic and can go at the front of the logbook, to be read and signed on joining. Masters standing orders and night orders deserve their own exciting post. But if done properly can help the skipper sleep soundly, knowing his instructions should be understood and that he will be woken when needed.

Finally another Shipping thing from the STCW these are some of the exciting Anti-fatigue rules we must abide by and they are worth considering as a minimum for yachts...
  1. All persons who are assigned duty as officer in charge of a watch or as a rating forming part of a watch shall be provided a minimum of 10 hours rest in any 24-hour period.
  2. The hours of rest may be divided into no more than two periods, one of which shall be at least 6 hours in length.
  3. The requirements for rest periods laid down in paragraph 1 and 2 need not be maintained in the case of an emergency or drill or in other overriding operational conditions.
  4. Notwithstanding the provisions of paragraphs 1 and 2, the minimum period of ten hours may be reduced to not less than 6 consecutive hours provided that any such reduction shall not extend beyond two days and not less than 70 (77 under IMO?) hours of rest are provided each seven day period.
If you have any fatigue induced error stories put them below, or any other comments.

Cheers

Ben

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