Dave,

Thanks again! I am not sure if I understand it all, but it makes sense to me.

I have excelent news:

The author of the article that started this discussion, Arnaldo Andrade, sailmaker in Cognac/Brasil (and also a physicist), sent me two replies, one of them quoting your words.

He wrote them fast after a day's work and asked me to edit, but I will just correct the typos. Some parts are marked "to be completed" and I will leave them as they are now.

[color:"red"]I will post both replies on his behalf as new replies to the initial post, so please go on with the discussion from there.[/color] I am sure that we will all benefit from the interchange of ideas.

Cheers,