"Jeff" wrote in message
. ..
Scout wrote:
Read that somewhere recently.
I knew downwind sailing was "it" for a very long time, but did the
concept of sailing to wind really come about with the evolution of the
wing and mechanical flight?
Scout

So this discussion tweaked my curiosity about just how weatherly the old
square riggers were. Some of the modern square riggers actually do fairly
well, with modern sailcloth and yards setup for getting to about 45
degrees off the wind, with modest leeway. However, the old ships couldn't
come close to this.

There was certainly a huge variation, and many ships could not go upwind
at all, but most of the ships made for exploration and general commerce
(as opposed to specific routes) could go upwind to a limited degree. And
there are famous stories of long and tedious beats to windward.

But what was the standard? Texts from 200 years ago, such as Bowditch and
Darcy, list six points as the closest you can make to the wind. This is
67.5 degrees. Some ships, such as the USS Constitution, were considered
quite weatherly, and did somewhat better, perhaps as much as a point in
ideal conditions, but this was a fairly recently development.

And how much leeway? Bowditch summarizes several other earlier writers
and claims:
"1st. When a ship is Close-Hauled, with all her sails set, the water
smooth, and a moderate gale of wind, she is then supposed to make little
or no lee-way.
2d. Allow 1 point, when the top-gallant sails are taken in.
3d. Allow 2 points, when the top-sails must be close-reefed."

And so on. So in ideal conditions, 6 points net off the wind might be
held, but if sails have to be taken in, the leeway is 1 point (11 1/4
degrees) or more. Bowditch finishes the navigation text section of his
book with an example journal of dead reckoning, "The journal of a Voyage
from Boston to Madeira." It includes all of the log entries shown with
speed, wind, and leeway estimates, along with notes on how to do the
various computations. All of the close hauled sailing is at 6 points off
the wind, with leeway estimates of zero, a half point, or a full point.
When footed off to 7 points, generally there is no leeway, but a few
entries list half a point. BTW, Bowditch was famous for the high accuracy
of his dead reckoning, so this technique, although it seems crude, must be
effective.

Ans what does this mean for the VMG to Windward? The cosine of 6 points
is .38, so if she were making 6 knots, the VMG would be 2.3 knots. With
half a point of leeway, that becomes 1.75 knots, and with a full point its
only 1.2 knots. In other words, a ship beating into the wind will make
some headway, but it might only be 30 to 40 miles in a full day. And its
easy to see that with rough seas, or an adverse current, or even a minor
mishap, all headway for a watch could be lost.

Jeff,
Thanks for the details - great reading!
Scout