976: Sail

Sail

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Title text: It only works a few times before you have to capsize the boat in a soap lagoon again.

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Explanation

This comic has been selected as This Week's Explanation for Improvement. Anyone is encouraged to help explain this comic! Every little bit counts; even just adding a sentence or fixing a typo is another step towards improving the wiki for everyone. Suggested improvements:   Explain whether this idea could actually work in real life, (with the right weather conditions)   How fast would the wind need to be to form a bubble?   What is Cueball pulling? Is he trying to create the bubble or govern the ship?   Would a boat be able to float in a "soap lagoon"? Click here to get started! If you are new to wiki editing, see our editing FAQ for guidance, or simply learn by doing!

A billowing sail sometimes looks like the first stage of blowing a bubble. A strong gust of wind blows by and fills the sail, which Cueball is clearly surprised by and fights to keep the sail under control. As the wind continues, the sail warps and begins acting like a film of bubble soap, eventually separating into its own bubble and floating off and the sail reverting to the original position, as the gust of wind dies down. Sails do not typically act like this under strong winds^{[citation needed]}.

If the booms and mast were actually attached by a rope on the far side, the sail frame could function as a large bubble wand. Commercial 'bubble ropes' can have an area of at least a couple of square metres, but it would need the right velocity and consistency of wind to sustain the bubble long enough to separate cleanly from the sail. This could, theoretically, be possible under extreme wind conditions, but it would be rare to find such winds.

The title text suggests that the water the boat is sailing in is a soap solution that can be used to create the bubbles. If the boat was overturned (capsized) in such water, a film would form between the mast and the boom. The film would become like the sail in the comic, filling with air and forming bubbles. However, with each bubble that is released the remaining film on the boat would become thinner, until it can no longer sustain itself, at which point it would need to be refilled by capsizing again. While this arrangement could be used to produce large bubbles with a sufficient film, Cueball would likely not have to pull on the mainsheet as much as is depicted in the comic, as the 'sail' isn't mechanically attached to the vessel for long, since it is a bubble film, not a piece of cloth.

Transcript

[Cueball is sailing a lateen rigged sailboat.]

[The wind picks up, pushing the sail forward.]

[The wind builds strength. Cueball has to stand up to hold on to the main sheet, with shaking depicting his tugging.]

[The distorted sail balloons out. Cueball is still holding on to the main sheet. More curves depict a stronger tugging.]

[Part of the sail separates into a bubble. Cueball falls backwards into the boat. The sail begins to return to its normal shape.]

[Cueball lands on his rear and scratches his head in confusion as the sail-sized bubble floats away.]

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Discussion

The explanation for comic 976: Sail was selected by the Explanation Improvement Project as This Week's Explanation for Improvement after being nominated in October 2026 by Titintheword. During that week, editors focused on expanding and polishing this explanation as part of an ongoing effort to keep older or under-developed explanations fresh and complete. (view the explanation before improvement)

Really doubting the Armistice Day thing.--Jimmy C (talk) 03:21, 29 November 2012 (UTC)

I agree. I've removed the mention. lcarsos_a (talk) 19:44, 12 December 2012 (UTC)

TWEFI 'questions' and my maybe slightly confused answers:

• Could this idea actually work in real life, with the right weather conditions?
  • You can blow bubbles purely with wind, yes, just hold the 'activated' bubble-blower wand up in wind within an appropriate range of strengths and let it do the job of you otherwise blowing through it or moving the wand through the air.
• In this xkcd universe, how do the sails interact with wind?
  • Like sails in our universe?
• Why is Cueball pulling a line? Is he trying to create the bubble or govern the ship?
  • From where it is shown attached to the boom, in every frame, it's probably just a standard mainsheet line. He lets it go slack to allow the boom to swing round, then holds it to stop it swinging entirely free and uncontrolled, so as to let the sail-bubble extrude properly.
  • Or else it's a halyard of some kind to control the exact "soap bubble wand/rope" that's pretending to be a sail.
• How would the "soap lagoon" work?
  • It's a lagoon. Full of soapy water. You'd sail in it. And maybe occasionally dunk your mast in it, apparently.

But I get the feeling that the questions need more/different explanation themselves, and that I've not answered what was actually being asked in any of these cases. 78.151.45.31 20:54, 17 October 2026 (UTC)

I tweaked them. They're just there so that new editors are interested in starting to edit our wiki. Feel free to add your own or remove irrelevant ones. FaviFake (talk) 22:15, 17 October 2026 (UTC)

"Is he trying to create the bubble or govern the ship?"

I think from his confused/surprised reaction in the final panel it's clear that he wasn't expecting this behaviour. 86.22.132.121 16:37, 20 October 2026 (UTC)

"Would a boat be able to float in a "soap lagoon"?" Yes. Citation: I put a Lego one-piece boat into a sink full of soapy water and it floated. SCIENCE! 7amiþ = moi.__init__(t, c) 06:31, 18 October 2026 (UTC)

Thank you for kindly providing your empirical anecdotical evidence, but that alone is not science (apart from the fact that man-sized boats usually are not made of LEGO plastic^{[citation needed]}); rather this is: Vessels float on the surface of fluids, not because of surface tension (which is used, e. g., by water striders indeed), but buoyancy; the latter boils down to the ratio of mean densities in the setting of a homogeneous gravitational field. Now depending on the soap, the soap water has the same density as pure water, give or take, whereas the density of the boat, including everything contained in it, has not changed; ergo the latter would float just fine. To put it differently, the hydrostatics of soap water would not change much compared to pure water—but the hydrodynamics might drastically so because of raised viscosity. – M. L. Juhos 134.60.67.135 07:37, 19 October 2026 (UTC)

397: Unscientific. It's not rigorous, because it wasn't meant to be: it was a reference to some of Randall's footnotes, where he'll state a fact, then say he tested it then and there, and finally cry SCIENCE! - because it's an empirical experiment. It was also a semi-joke. (Follow-up: I wonder what the America's Cup would look like if it had been raced on 5%v dish soap soln...) 7amiþ = moi.__init__(t, c) 01:02, 20 October 2026 (UTC)

My first edit (the page did say 'learn by doing'), added some wikipedia citations to make the article internally consistent and tried to expand on the possibility of bubble boat a little bit.Meltro (talk) 07:54, 20 October 2026 (UTC)

Welcome to exkcd! Just as a note, we use in-text references and external links here. Thanks for the contribs! 7amiþ = moi.__init__(t, c) 17:59, 20 October 2026 (UTC)
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