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Clive asked-

Does  anyone know of a really good way of checking leeway?

=============================

Presumably we're talking about motion of some sort of yacht, with a
real keel, and not a motor-boat.

Then I ask, what's the problem about checking leeway? Just guess it;
that's what I do.

Steering a sailing craft is a pretty inexact science at the best of
times. Leeway only becomes appreciable (couple of degrees?) as the
vessel gets to a close reach, and gets important (5 degrees?) only
when close-hauled. In awkward conditions (short chop which takes her
way off, from time to time), perhaps 10 degrees. Rough conditions,
rather more.

When sailing close-hauled, my wife is usually given the tiller, as she
does a much better job than I do, having that knack of getting the
right compromise, and making more ground to windward. After a time,
inattention gets the better of me. So, with me at the helm,
close-hauled, the allowance for leeway should be somewhat more.

I have an old Walker log (the mechanical type, towing a spinning
propellor). When out of harbour, there's usually the log, or a fishing
line, towing from the transom (not both, because they tangle). But any
old object, towed on a string, will suffice, to provide a
back-bearing, by handheld compass, on the direction that such a line
leaves the stern. Adjusted by 180 degrees, this provides a good true
course, already corrected for leeway, if that's really needed.

I remember a voyage, years ago, not in my own boat, which happened to
be liberally provided with sliced white bread, that tasteless
substitute for a real loaf. Slices were thrown from the bow now and
again, and timed in passing from bow to stern, as a Dutchman's log.
Prior to their sinking astern, compass bearing gave a measure of
leeway. It was the most useful thing we could do with the stuff.

====================

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.






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