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xkcd #3193: Sailing Rigs
(imgs.xkcd.com)
Title text:
I wanted to make the world's fastest yawl, so I made the aft sail bigger, but apparently that means it's not a yawl anymore! It's a real ketch-22.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3193/
They rotate not by harvesting the wind but by pushing against it. I.e. are motorized.