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> Bill wrote-
>
> "If I understand, DR is course and speed.  Once you factor in set,
> drift and
> leeway you are into the area of EP (estimated position)."
>
> I'm not sure what Bill implies. Is that really what the books, and the
> training courses, teach nowadays? Surely, if you're going to draw a
> line on your chart, representing your passage through the water, it
> makes sense to estimate a leeway correction to your course, there and
> then, before drawing that line. That's what I have always done, and I
> presumed that's what others did also. Perhaps I'm just out-of-touch.
> But if it's common practice to plot a course without allowing for
> leeway, then include it later with current set, can someone explain to
> me the rationale behind it?
>
> What, in this context, is "drift", as distinguished from "set", and
> "leeway"?
>
> George.

George

First, the whole deal on a (relatively) small sailing vessel is somewhat of
a guessing game.  You take your best educated guess of the average speed
for, say an hour.  You take your best guess at average course.  D=S*T gives
you a baseline without other, more fuzzy variables.  Call that DR.

Now add in any known helmsman idiosyncrasies (in some schools, add that to
DR), current set and drift, and leeway to establish an EP.

In practice, you and I are doing the same things, I see it as a matter of
semantics.  To that end, I define leeway as GOG vs where the lubberline is
pointed--with no current. I define set as the angle any current is heading
towards (as opposed to wind, which is the angle the wind is coming from).  I
define drift as the speed of the current.

Put another way, imagine a tide stick several feet deep but with only 1"
above the water so wind and waves will have little affect on its motion.
The resulting direction and speed are set and drift respectively.

Now imagine a board boat on a lake with no current.  Sail close hauled with
the dagger board down.  Your COG will not equal your compass heading.  That
is leeway.  Now pull the dagger board up.  Your COG will not equal your
compass heading, to a greater extent.  That too is leeway.

But I bet your already know the above, and I have to go racing and Great
Lakes sailing in 7 hours, so I'll continue when I return if I have not
adequately answered your questions.

BTW.  If "teaching nowadays" includes 47 years of recreational sailing in
CT, RI, NJ and the Great Lakes, yes.  On the other hand, if you recall the
discussion of current texts' definition of "Angle on the bow" vs. "Relative
bearing," who knows?  It would be nice if the definitions were all the same
for learning/teaching, but in the end do you have the global overview of the
forces in play to get from point A to point B in a safe and efficient
manner?

Bill

Bill





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