Thanks for the reference. I only have the 1996 version of Hecht
(with calculus) in my office. Thanks to your directing me to the
problems, however, I did find Discussion Question 17 which seems
to deal with the problem. It also has the Flettner rotor ship. I
will take it home with me for some light reading and get back on
when I figure out what he has to say. Thanks for the tip,