Quote:

> >the optimum sailing angle can not be determined from a simple vector

> >analysis, i.e a decomposition of the net-force-vector.

This is a correct statement as there are a myriad of variables.

Quote:

> But vector analysis ---snip--- use some help...

You can get pretty close to it using vector analysis as there will be a

point in the polar VMG diagram where the available driving force due to

the velocity squared (apparant wind) function is balanced by the course

dependent forward component of the lift vector. However, you will have

to know or make some assumptions regarding lift/drag coefficients,

sheeting angles, wind speeds, drag from the board and fin, degree of

side 'slip, degree of 'perfectness' of air as a fluid, water surface,

etc.

AND, the biggest variable will be the response of the board as a

function of driving force, as the faster you go the more the apparant

wind moves forward.

This is all a good rainy day exercise and perhaps an interesting

Master's Thesis, but a lot more fun on the water. Just get on a solid

close reach and start bearing off. It will become obvious within a few

seconds for your particular set of variables and best of all, porter

beer belliedness is automatically included...

I believe Sailquik has done this with his GPS (for his set of

variables.) Roger?

- Bill Hansen

Sail Design/R&D

Windwing