wrote in message
oups.com..
..
A question sometimes asked is that if you have a large fan
at the
stern on a
sailboat blowing forward into the sails would that propel
the boat
forward? The usual answer given is no because the fan
blowing air
forward would produce momentum propelling the boat
backwards. This
would swamp the effect of an effective wind acting on the
sails.
But suppose instead you had the fan in front blowing
rearward into the
sails?
In this case the momentum would propel the boat forward.
Furthermore by
using the method of tacking into the wind, the wind
blowing into the
sails could produce a force with a forward component as
well. Then the
acceleration forward should be higher than that produced
by the
momentum flow of the fan alone. The speed could also be
higher than the
speed of the air created by the fan since tacking into the
wind can
give you a higher speed than the wind speed.
Would this work?


Of course it will. Haven't you ever watched a Popeye
cartoon?

SV