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Comment by hownottowrite | Hacker News Reader

The article says there are 15 in operation with 5 more coming in the next year. I couldn’t find details on those ships but the MV Afros is a working cargo ship outfitted with wind assistive technology.

https://www.nytimes.com/2021/06/24/magazine/cargo-ships-emis...

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The 15 in operation are not the puffy sails that the headline is talking about. They are a rotor design by a different manufacturer. The rotor style sails can save about 10 to 20% of a ship's fuel https://theicct.org/sites/default/files/publications/Rotors_...

Found this awesome simple demonstration of Flettner rotors.[1]

One question I have is, how would this work with a sort of semi-circle fan version, where the blades retract when they start getting pushed into the wind. This could theoretically have the rotor turn off of just wind power instead of external power. Here's a crude drawing lol [2].

[1] https://www.youtube.com/watch?v=XsGin7CFaF8

[2] http://draw.to/D47BxHT

Informative video on how it works [1]. Btw the 20% is an overly optimistic scenario.

[1] https://youtu.be/JhAlWHSez90

that's a great paper! I love that it walks the reader through the math! I wish more did that! I often feel papers I read are just a little outside my abilities, but this one actually makes a person smarter!

I think most papers do this mostly to prevent too much scrutiny of their calculations. Publish or perish etc

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