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Comment by FrontAid | Hacker News Reader

The article does not really explain how it works. From my naïve understanding, those wings sails do not seem to be ordinary wings but are shaped like the ones in airplanes. When they are rotated to the right angle given the wind direction, the vessel is pulled forward. The topic reminds me of the Flettner rotor [1] and other wind-assisted propulsion systems [2].

[1] https://en.wikipedia.org/wiki/Flettner_rotor & https://de.wikipedia.org/wiki/Flettner-Rotor

[2] https://en.wikipedia.org/wiki/Wind-assisted_propulsion

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They work just like normal sails. A sail is just a wing sideways. It moves the ship by generating lift.

The ship moves forward when the angle of attack is adjusted correctly. See the picture: https://en.wikipedia.org/wiki/Point_of_sail#/media/File:Poin... The ship can't move directly against the wind, but it can close-haul 45 degrees against the wind assuming it has enough keel.

Not sure about that. Normal sails "bend" away from the wind and thus have a much stronger lift. This concept's sails are "beant" outwards and would lose much of the wind's force. This source [1] states that "The futuristic sails are like airplane wigs using the same level of aerodynamic technology" which would imply that they absolutely do not "work just like normal sails".

[1] https://www.maritime-executive.com/article/swedish-collabora...

https://en.m.wikipedia.org/wiki/Airfoil

Wingsail works with the same principle as conventional sail, it's just more efficient (hang gliders use the sails to fly).

Wingsails like this generally have a 3x to 5x advantage in lift/drag ratio for equal area.

> The ship can't move directly against the wind

Is that a fundamental physical limitation, or would it be possible to come up with a design that allows moving directly against the wind (while being fully wind-powered).

(EDIT: ok, answering my own question: I guess you could anchor the ship and use a wind-turbine to charge a battery, then use that energy to move a bit, anchor again and repeat)

Wind turbine ships can sail directly into the wind. There's no need to anchor or store energy — you can just power the propeller directly from the turbine.

> The article does not really explain how it works.

It's a sail. Being rigid instead of a piece of cloth doesn't change the basics of how it's working.

https://en.wikipedia.org/wiki/Sail

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