Ryk wrote:

Yes, a tight course is important near shore or other hazards, and
essential in traffic, but is it necessary out on open water? 15
degrees of wandering costs less than 4 percent in course made good
and few cruisers put the effort into trimming sails that
efficiently. A DR track can only be as good as the course keeping.
Are there other reasons than DR to try to steer a tighter course?

I tend to think that steering error itself is not inherently the issue
offshore. What it boils down to is: "How do I get to the destination from
where I am _right now_?" This becomes more important (or even critical) as
the distance to the destination decreases

In any kind of offshore leg the effects of current, leeway, inattention,
instrument error, etc., will usually put the boat off the rhumb. It then is
up to the pilot or navigator to adjust the course to reach the destination.
Even in a short leg, say from Maine over to Yarmouth, this happens many
times in the course of a single crossing.

With respect to the degree or error that you suggest, I think that the
actual error that is attributable to the helmsman himself
will be buried in the overall set of other factors, and will be almost
impossible to isolate. However if you find you are visibly "wandering" 15
degrees off the desired heading, then it is probably time to concentrate
more.

BTW, neither my autopilots nor my steering vane show this kind of error over
a relevant time period.

--
Good luck and good sailing.
s/v Kerry Deare of Barnegat
http://kerrydeare.home.comcast.net/