Part 5 of the series “The Science of Sailing” has been allotted to four distinct topics. The first of these is associated with force- and moment equilibrium and free moments—the basis for the calculation of the performance of sailing craft. The second deals with the lift, drag, and moment properties of foils and foil sections such as keels and rudders. The third covers the design and performance of different hull forms, and the fourth is my personal account of the design of “Australia II”, the yacht that won the America’s Cup in 1983.See: https://oossanen.nl/the-science-of-sailing-books/