I'm not much of a sailor, but I am mathematically inclined...
Here's a little table of what a difference in 5 degrees pointing
makes in your actual upwind speed:
10-5 degrees: 1%
15-10 degrees: 2%
20-15 degrees: 3%
25-20 degrees: 4%
30-25 degrees: 5%
35-30 degrees: 6%
40-35 degrees: 7%
45-40 degrees: 8%
50-45 degrees: 10%
55-50 degrees: 12%
60-55 degrees: 15%
65-60 degrees: 18%
70-65 degrees: 24%
75-70 degrees: 32%
80-75 degrees: 49%
85-80 degrees: 99%
90-85 degrees: infinity
That is, if you can point at 30 degrees off the wind instead of 35
degrees off the wind while maintaining the same boat speed, your true
upwind speed will increase by 6%. Alternatively, it means that if
you point 5 degrees higher than 55 degrees off the wind, and you
pinch and slow down boat speed by 12% or more, you have gained
nothing in terms of true upwind speed.
At 90 degrees you make no forward progress at all, of course. The
extreme numbers at the top are meaningless for sailboats, though I
understand that ice boats can point *very* high, and can get up
incredible speeds (they are going so fast that the apparent wind is
shifted a great deal from the true wind).
These are purely theoretical numbers, of course.
-- Kent Crispin "Do good, and you'll be kent@songbird.com lonesome." -- Mark Twain