The secret every paddler should know: the science of gunwale bobbing

Perhaps you too were routinely chastised by a camp counsellor for standing up in a canoe. But a group of scientists wants you to forget all that and take a stand on gunwale bobbing.

Gunwale bobbing (pronounced “gunnel”—“one of the delights is its funny spelling,” says Stephen Morris, a physics professor at the University of Toronto) is an odd pursuit with little purpose beyond novelty, the glee of thumbing your nose at dictatorial camp counsellors, and the chance to test a theory of quantum physics.

At least that was partly the motivation of Jerome Neufeld, a professor of earth and planetary fluid dynamics at the University of Cambridge and a cottager on Muldrew Lake. Neufeld remembered gunwale bobbing from his childhood—the goal then was to see who ended up in the lake first—and decided to pass down the pursuit to his kids.

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Gunwale bobbing involves standing up in a canoe and creating waves by bouncing up and down, then riding those waves to move the canoe forward. Or, more academically, it’s “a phenomenon in which a person jumping on the gunwales of a canoe achieves horizontal propulsion by forcing it with vertical oscillations,” as described in the American Physics Society’s journal Physical Review Fluids.

Neufeld routinely finds himself “explaining fluid phenomena in the natural world,” he says. Gunwale bobbing turned into the perfect opportunity to demonstrate how a particle can be both a wave and a particle, a vexing ancient problem in quantum mechanics.

Physicists came up with a demonstration a few years ago, using liquid. The demo showed that if you shake a layer of fluid, and you put a little droplet of fluid on its surface, instead of just falling into the fluid, the droplet bounces up and down. “And that little bouncy drop can start to ‘walk’, to move across the fluid,” says Morris.

It was Jerome, Morris says, who noticed that the reason that the droplet moves is simply that it makes waves and then “surfs” on those waves. Neufeld summarizes it this way: “Long story short, the droplet and its wave then behave like a quantum particle/wave, and so can mimic many nanometre scale phenomena.”

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Fast forward to Neufeld holidaying and gunwale bobbing at his Muskoka-area cottage. The canoe, he realized, was doing the same thing as that surfing droplet. The physicists, great fans of wordplay, call it the “quantum canoe.”

When Neufeld, Morris, and their research colleagues got together to produce their paper on the bouncing droplet, the Powers That Be at the journal in which it was published wouldn’t greenlight mention of the quantum canoe. But it does use the same math, Morris says.

Though I, a Canadian, had never heard of it, Morris insists that “gunwale bobbing is a Canadian thing.” And it’s a Canadian thing that fellow Canadian, Neufeld, thought “needed an explanation.”

The applications of this research varies from better understanding the energy created by boat wake (and thus shoreline issues) or even ways that Olympic canoeists can increase their speed.

But, says Neufeld, “Being able to explain the physics of the phenomena is, honestly, mostly fun and I’m delighted there are fun new ways the kids can viscerally explore waves when they’re playing in the water at the cottage.”

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