... levers and pulleys give a _tremendous_ amount of
mechanical advantage if you understand a few basic
principles...

Thanks for your suggestion. But at this point, I think I will avoid a
boat that has many major damages in the bottom that are so severe that
require me to roll the boat up to have a clear way of the bottom. I
figure that if I narrow my selection to boats that have very limited
damage (if any) in the bottom, I probably can get by without rolling
the boat.

Jay Chan