The book is dated 1949 last modification 1957

This is an aerofoil book and not a surface piercing foils book.

surface piercing foils have progressed a long way since the 50's.

I'll bet my bottom dollar that this book only deals with high speed aerofoils and does not handle low speed aerofoils like sails and handgliders. let alone surface piercing foils which are daggerboard and rudders. Even just submerged foils like keels notice the proximity of the watersurface and display abnormal behaviour when compared to foils surrounded by one one medium with no transition bounderies.

It may be a good starting point for complete novices but Steve won't find the answers to his question in this book.

Wouter