A 127-year-old physics riddle regarding the Kelvinangle in boat wakes solved

&gt; <i>&quot;Fuel consumption can double if the vessel is traveling downstream compared to upstream,&quot; Ellingsen said.</i><p>This is counterintuitive. The fact that it&#x27;s easier to make waves traveling upstream must outweigh the fact that if you&#x27;re going downstream the water, you know, carries you.

Can someone please explain to me why this is so groundbreaking? If I blow a smoke ring and there is no wind my smoke ring stays circular. If there is wind blowing from the side my smoke ring will become distorted. Likewise if there is a current in water then I expect that current to disturb the propagation of waves moving through the water, not so? The medium in which the wave is propagating is itself moving.<p>Surely this has not remained a mystery for 127 years.

Other interesting physics riddles solved after some time:<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Feynman_sprinkler" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Feynman_sprinkler</a><p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Blackbird_(land_yacht)" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Blackbird_(land_yacht)</a><p>And the infamous plane on a treadmill..

I hate the way this article is presented.<p>It takes an interesting and intuitive effect that we couldn&#x27;t explain mathematically and now can, and tries as hard as possible to shove every fucking clickbait word in as possible.<p>Kudos to the author for presenting this material in possibly the least consumable way imaginable. I hate it.

I understand that there is now proof of the usual V-shaped wake angle not always being ~39 degrees depending on subsurface currents.<p>I&#x27;m a bit confused about the ring waves part of this article. How is the boat leaving a ring wave when it moves? Or is the boat just being lowered into the water to form a ripple? You can&#x27;t tell this from the top-down view.<p>For some reason, the way that the article was written made it seem that a boat moving through the water could leave an off-center ring wave wake, which makes no sense.