Not quite the same as the two magnets. If you have a big fan and a square sail, you’re moving air, which has mass and is not attached to the boat. That alone will cause a force that moves the boat backwards. The moving air that hits the sail will not fully cancel that force due to frictional losses and air spillage from the edges.
Racing yachts are a different story. They have rigid sails that are shaped like airfoils. Blowing across an airfoil causes lift. So a big fan blowing perpendicular to the axis of the boat across such a sail would move the boat forward. But it’s much more efficient for the fan to blow backwards without the sail, hence airboats and hovercraft.
If you’d blow with a leaf blower or something to the front of the boat, the boat might actually go backwards of there’s enough force. The leaf blower is basically pushing the air forwards, therefore it’s also pushing itself backwards. Some go this will probably be cancelled by blowing against the sail, but some air will also pass around it.
I think it’s the same as trying to give a sailboat acceleration by trying to blow the sails while standing on deck.
Not quite the same as the two magnets. If you have a big fan and a square sail, you’re moving air, which has mass and is not attached to the boat. That alone will cause a force that moves the boat backwards. The moving air that hits the sail will not fully cancel that force due to frictional losses and air spillage from the edges.
Racing yachts are a different story. They have rigid sails that are shaped like airfoils. Blowing across an airfoil causes lift. So a big fan blowing perpendicular to the axis of the boat across such a sail would move the boat forward. But it’s much more efficient for the fan to blow backwards without the sail, hence airboats and hovercraft.
If you could scale the strength of blowing all the way up this would actually work though no?
For example, if you were in a light kayak with a mini sail and had a high powered leaf blower pointing at the sail, would that work?
If you’d blow with a leaf blower or something to the front of the boat, the boat might actually go backwards of there’s enough force. The leaf blower is basically pushing the air forwards, therefore it’s also pushing itself backwards. Some go this will probably be cancelled by blowing against the sail, but some air will also pass around it.