Airplanes deploy revers thrusters when landing which are basically just shaped metal shields that move into place behind the engines to provide reverse thrust and slow the plane.

But adding a fan on a sailboat is seen as stupid and doesn’t work.

  • Fan on a boat does work, just not efficiently enough to overcome anything but static air if you’re talking about facing the fan into a sail and not something like an airboat. Put a jet thruster on it and it would work really well. But an airboat with opposing fans would also work.