thank you all for the informative discussion.

Henry Miller ("Sailing Yacht Design" (1965) also disagrees with me,
writing "As the driving medium, the size of the sail plan obviously should
bear some relationship to the resistance of the hull. Unfortunately there
is no direct means of evaluating the driving force that can be produced by
a given size sail plan under specific wind conditions." That seems odd to
me. Surely a somewhat idealized model can be described mathematically and
boundary values computed. I'm having a samilar problem comparing heeling
force of the sail to righting moment of the hull and crew to see how much
sail to carry. The books discuss the Dellenbaugh the angle I was asking about
in an earlier thread and another method both of which depend on
measurements taken from the dynamics of the completed hull or model. I must
declare I'm disappointed. I think I'll keep working on these analytically
to see if I can get any useful numbers.

I appreciate the need to compare with data from exsisting boats to check
any calculations. I realize its the practice among yacht designers to use
comparisons where they can't calculate numbers analytically. I've got lots
of data on specific day sailers and light crusiers to use, and some
scatterplot summaries of data on daysailers and light cruisers, all from
books at the public library. The design I'm playing with appears to be
reasonable by comparison. As I work on the design I have to answer a lot
of questions which refine my ideas about how the boat will be used and
under what conditions. Its interesting to try and come up with a roomy
ultralight cruiser with sufficient power and response to work the shifty
winds on inland lakes and rivers like the waters we have on the Rideau
system, hopefully without resorting to auxilliary power.

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