I know this is different from the "stock book" answer, but this is
what our experience has shown us.

Last year we had 3 legs of  10 days or longer, and a bunch
7 days of longer.  Any leg of over three days had at least four
crew who usually were not experience passagemakers.

I tried fixed watch schedules and found that with our experience with
four people in the watch schedule they did not work as well as
I had hoped.  (This pained me because I liked planning when my
watch was, but for overall safety, flexible watches ones were
clearly better).

Since our crew was often times changing and was not experienced
they often times not sleep well at first or when the seas "kicked up".
Also if we had a problem sleep was hard to come by.  We listen to
a mayday relay for four hours when someone sank, no help was
forth coming, no sleep for anyone that night.  (They we closer to
help then we were, what if we needed help?).

This is also important when someone was gets sea sick. Usually
we had at least one person got sick on most of our legs.

This is especially true on shorter legs of three or four days.
When the other crew is still trying to get a boat rhythm.

Fixed schedules did not work as well as flexible ones because
sometimes people were not as "up" for watch as others.
I did not want someone standing watch who as not able to
maintain a good visual watch.

What we found worked best was.

Whoever was on the flybridge was on watch.
(Our flybridge has 10 inch NavNet screen so they
get a full size chart plotter and/or Radar (with overlay),
full engine instruments, 2VHF radios and can bring
a Satphone handset up).

Since the person/people on the fly bridge are already
looking out they can do a watch for "free"!

Secondly during the day people who can not
read a book generally "do not mind" doing a watch.
A watch in daylight with good visibility is low work,
stress and gives them something to do.  Usually someone
else will come by and talk to them etc.

At night a fixed schedule is necessary, especially the
"bedtime" to sunrise timeframe.  We never found a
really good one.  Someone would always have trouble
sleeping.  If someone was too tired to stand a full watch,
the rule was get the next person.  I know I left watch
early at least once, and I was woken up a couple of times
early, but it was not a problem.  I would rather stand a four
or once in a while five hour watch, then have someone who
is too tired to do it well.

We found three hours works better then four hours.
It was hard to stay awake from midnight to four, it was much
easier to stay awake midnight to three, and if someone
had to stand a longer watch they had a little extra to give.

You have to work with what is best for your crew.
the same answer will not always work.

I have wondered what made our experience so different
from other people?

Anyone want to comment on why?

Scott, I find your plan interesting and responsive to the realities of your crew.

Our experience aboard Odd @ Sea was different. There were 5 crew on board, 2 women and 3 men. The men in particular were experienced watch standers with 10's of thousands of miles each. The women were a little less experienced.

We started with three hour watches in a 4 watch rotation day and night, with the two women standing a watch together. We reviewed this plan many times but no one want to change at all so every leg of the transatlantic crossing we used exactly the same rotation. The day watches often had substitutes for a while but the night watches never did. The plan was if there was a need, the next person, or the captain could be called at ANY time.

I think we all felt this worked well for us.

John Harris