Wind blowing on bare poles will make the boat go.

The apparent wind created by a boat drifting withe the current (in still air
relative to the ground) will make it go faster than the current.

Yes, the fan blown into the sail at the correct locations will increase boat
speed. Blowing it from the rear and using ballistic theory will not yield
the true answer. Blowing the fan over the sails and correctly applying
Bernoulli's Laws shows the sailboat will indeed move forward. Under the
right conditions the sailboat will move faster than the windspeed of the
fan.

I am an intellectual (Mensa member in good standing), look great in Speedos
and wonder if LP is available. Kates keeps on standing me up - without
Viagra!

Jax