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/
I forget what they are called, but there is basically a parachute on a rope that gets dropped into fast deep water currents to tow boats.
That's called a sea anchor.