There are many field examples[1] of motorized, wheeled vehicles capable of staying on the surface of water. It appears that the requirement is sufficient "reverse-pressure" against the part of the water surface being interacted with. Can somebody explain the physics of this? and...

Question: Is it possible for a stationary wheeled vehicle to remain on the surface of water? For instance, would a vehicle with two powered wheels turning in opposing directions be able to remain on the surface? Maybe wide, slick wheels... à la Tesla turbine?

[1] Snowmobile: https://www.youtube.com/watch?v=6gNNcdsjvso

Quad: https://www.youtube.com/watch?v=SWWt9IC7mGs

Dirt Bike: watch?v=oD3BVxQm6ds

Buggy: watch?v=Eo77vgUK6iQ

  • $\begingroup$ I am afraid you question contains a lot of loopholes that offer several easy solutions and cannot be closed without ruining the question. For instance, you cannot really stay above water, at least some part of the vehicle has to be a bit sumberged, to be in contact. How much submersion do you allow? Why? Do you allow some fins or rotors attached to the wheels? Or what about if finned wheels spin so fast that the vehicle will essentialy almost fly above water thanks to redirected air? I think the answer is obviously yes. It is possible for stationary vehicle to remain on the surface. $\endgroup$ – airguru Dec 1 '15 at 22:14
  • $\begingroup$ I kindof see your point. So, in the case of finned wheels (if its even possible), what exactly is the physics where, at some speed, the up-pressure and the equal down-pressure of semi-sumberged, finned wheels keeps a certain weight of vehicle from sinking (completely) below the surface... and more importantly, why? $\endgroup$ – Sy Moen Dec 1 '15 at 23:36

All of these vehicles are functioning exactly like a waterski; they are impacting the motionless water and pushing it down, thereby being themselves pushed up. The only difference is what keeps them moving; a waterskier is pulled by a boat, the snowmobile is pushed by the ribs on the belt, and the ATV is being pushed (somewhat) by its wheel treads.

But, the all depend on impacting new, motionless water so they can push it down and thus keep from sinking. Notice in the video of the ATV; when it was mostly across the bay it was slowing down and sinking further. Had it completely stopped, it would have sunk, as would have the snowmobile.

A vehicle can stand motionless on water if it has some sort of propeller to thrust the water down, sort of like an upside-down helicopter. Simple spinning wheels won't do it, though.

  • $\begingroup$ Okay, even a razor blade on edge with enough velocity could skip / hydroplane for a while. So... there must be some generalized equation that says something like: fx(velocity) * fy(surface area) = buoyancy These functions must derive from the compressibility or plasticity of water. If this is the case, isn't there a sort of phenomenal scenario where velocity achieves general resonance with water compressibility and stationary buoyancy is possible? $\endgroup$ – Sy Moen Dec 2 '15 at 22:47
  • $\begingroup$ ahh... like maybe this "Woboba ball" which seems to be designed to achieve simple resonance with water --> youtube.com/watch?v=k4767cZzS28 $\endgroup$ – Sy Moen Dec 2 '15 at 22:57
  • $\begingroup$ Don't use the word "buoyancy"; it doesn't apply here, and is confusing. And, water's minuscule compressibility is irrelevant here. The Woboba ball works because it is impacting the still water, and then moving on to impact elsewhere, just like the waterski. None of this will help your stationary wheeled vehicle to stay on top of the water. $\endgroup$ – Daniel Griscom Dec 2 '15 at 23:09

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