Comments on: Episode 56: Killer Whirlpool

By: Justin S

Justin S — Sun, 11 Jul 2010 19:11:52 +0000

Mythbusters should redo the Snow plow with car myth
I live in wisconsin and during are winter session we get 60 to 90 mile per hr winds, if you add wind to the factor with going 70 miles per hr on the road you will flip another vehicle, with all that wind being forested against the blade of the snow plow angel towards the car the force will tip a light weight car over.

By: Oslofyr

Oslofyr — Sun, 02 Aug 2009 18:22:00 +0000

The worlds largest tidal worldpool is not in Canada, but Saltstraumen in Norway.

Bad research, boys.

By: Tristan

Tristan — Fri, 10 Apr 2009 05:48:09 +0000

I would love Mythbusters to bring back the Whirlpools. As a whitewater kayaker I am around moving water all the time. I think it has to do more with volume of the water and a bit of geography, what the water is being forced through or around, as we know this and gradient is what forms rapids and other features such as whirlpools. The ocean is a bit of a different story since the gradient, more or less, is the tide going in and out. But Tidal rapids are still formed by compression, all that water between a few islands at 14 knots…something is going to happen.

A whirlpool can definitely drown a person, one river I work on this has happened. On this same river I have gone for a few rides for a number of seconds underwater in a 70 gallon kayak. The best example I have seen to illustrate a “Killer Whirlpool” would be Skookumchuck Narrows near Vancouver Island in Canada. Here I have seen people in their kayaks disappear for 40-50 seconds!(they lived but didn’t get back on the water) Yes, still no ship but definitely impressive and scary.

There are rarely whirlpools that will sustain their shape or position…they usually come and go. But it is possible to go from one whirlpool to the next. This I have experienced in smaller whirlpools on another river I work on, a fun little spot to voluntarily jump into the whirlpools for a 10-30 second ride ( underwater with a PFD on). These whirlpools are only about 3-4 feet in diameter and I wouldn’t doubt this could drown someone without a PFD or Lifejacket on. There is also a crazy sport out there called squirt boating. Where you are in a kayak that has extremely low volume and they are designed to be pulled down by an eddy line or whirlpool. I have seen these kayakers disappear for 10-40 seconds on purpose and apparently the longer you are underwater the better.

In the end could whirlpools sink a ship? A tanker well highly improbable but a fishing boat, sink yes, pull the boat underwater instantly, very unlikely. I would love to see the dust blown off this myth for another go.

By: Mr.Woob

Mr.Woob — Tue, 10 Mar 2009 03:55:16 +0000

Lake Peigneur was considered a whirlpool. If you can show me one definition of a whirlpool that does not simply state a circular current of water that near by objects are drown into then I retract my statement. Everything I found considers it a whirlpool and it did happen. A lake went from 10ft deep to 1500ft deep. That is a crazy bathtub and I cannot find any other “bathtub” like it.

By: Persojet

Persojet — Sun, 14 Sep 2008 15:10:19 +0000

for the snowplow thing could you test the myth with snow conditions and not in “summer”

By: Dick Veldkamp

Dick Veldkamp — Tue, 25 Mar 2008 09:19:28 +0000

Distance/time scaling.

For the scaling to be right (i.e. the flow problem resulting in the same Navier-Stokes equation) two numbers should remain the same:

Reynolds number Re = rho U L / Eta
Froude number = Fr = U / Sqrt(g L)

g = gravity’s acceleration = 9.81 m/s2
L = ship’s length [m] (and vortex dimension)
rho = water density = 1000 kg/m3
U = speed [m/s]
Eta = water’s dynamic viscosity [Ns/m]

Supposing we have only speed U and dimension L to play with, clearly we cannot keep both Re and Fr constant, because that would mean that simultaneously:

U L = c
U / Sqrt(L) = c

I don’t know offhand which number is most important in this case, but my guess would be Fr because a vortex shape has to do with speed and gravity (we may usually allow Re to vary within a decade without significantly changing the problem)

This would mean that we have to scale down speed U as the square root of the dimension L.

By: Andrew

Andrew — Sun, 10 Feb 2008 05:27:00 +0000

I really think the snow plow myth should be revisited. I compleatly agree that the test peramiters were all wrong. First thing I noticed was that the weather was all wrong, I have passed big trucks and snow plows on a nice calm clear day too and didn’t even notice anything, icey roads or not, its the wind that makes the differance. If you had a tail wind of 100 km/h, which isn’t unheard of in southern alberta, and you met an oncoming snowplow going 115 km/h that would mean that truck is moveing through the air at 215km/h. believe me you sure feal that in what ever kind of car or truck you are driveing.

By: bob miccoli

bob miccoli — Tue, 08 Jan 2008 06:15:05 +0000

In regards to tidal vortex, look up the Knox Mining disaster near Pittston , PA.It happened in 1959 when coal miners dug too close to the river.they tried to plug the hole by dropping railroad cars into the vortex.Maybe not a “tidal vortex’ but a great illustration of the force of water.A short video exists showing the event. More info can be obtained from The Lackawanna Coal Mine Tour in Scranton , PA
Bob

By: trevor

trevor — Tue, 06 Nov 2007 03:22:51 +0000

I missed most of this episode but the road they were travelling was it icy or dry obviously that would make the difference. You usually only see snow plows after a storm.

By: Michael Carnevale

Michael Carnevale — Sat, 03 Nov 2007 20:21:35 +0000

You did the snowplowing myth all wrong. You should have the plow and the truck going in the same direction, with the car possibly stationary, the snowplow passing the car on the left while plowing snow. You had the plow facing the wrong direction when you did it. So your BUSTED.