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Old 08-13-2005, 12:21 AM
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Pull force

Does anyone know of any tests done to find out the amount of force that is absorbed by a ski rope when a slalom skier is cutting across the wake full bore??? It seems like it would be a simple matter of placing some kind of strain gage in the rope. A non-skiier asked me this once to get an idea of the strength required to ski at a high level.

Any scientists out there with the proper equipment to do the test???
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Old 08-13-2005, 12:36 AM
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A device called a load cell that can read out the force.
(You were right, a load cell has strain gages in it.)
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Old 08-13-2005, 12:56 AM
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Quote:
Originally Posted by Powerslot82
A device called a load cell that can read out the force.
(You were right, a load cell has strain gages in it.)
Yeah, that's what we'd need. But it would have to have some way of recording or marking the max force, kind of like a g-meter that tells you the max g's you had...
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Old 08-13-2005, 02:51 AM
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You could mount strain guages on your ski pylon to measure the maximum deflection, then from there, there are some equations in which you could use to calculate the force, since the properties of aluminum are readily available. Howevery you'd need some kind of data logger that could keep track of very small voltages since strain guages put out very little signal. Another option would be to make some marks on the rope of a known distance, then measure the change in that distance while the skier was skiing, and then use the maximum deflection and tensile characteristics of the rope to calculate a force.
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Old 08-13-2005, 04:25 AM
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I would think you could calculate it with speeds. The boat is going away at 36 and your going accross at 80 or so I believe. Too late to break out a pencil but I would bet it wouldn't be that hard to figure out.
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Old 08-13-2005, 10:34 AM
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please dont make me break out my old college Physics book........
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Old 08-13-2005, 10:44 AM
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Put a scale in line with the rope. If you could find a fish type scale with hooks on each end.

I was reading in the official water ski association how they qualify boats to be "official ski boat" and one criteria was the pylon had to be able to handle 1323 pounds of pull. I would guess a good skier pulls 150-200 pounds at peak.
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Old 08-13-2005, 12:05 PM
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Cmon Leroy, you are an engineer. Break out the calculator and get us an answer
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Old 08-13-2005, 12:10 PM
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I would bet higher than 200. MAybe not every day Joe but tourney guys for sure. I will let you know as I have one of those Zebco fish scales and a cousin I call the "Test Monkey!" He will do anything. I think the scale will explode but that is his problem!
Quote:
Originally Posted by Leroy
Put a scale in line with the rope. If you could find a fish type scale with hooks on each end.

I was reading in the official water ski association how they qualify boats to be "official ski boat" and one criteria was the pylon had to be able to handle 1323 pounds of pull. I would guess a good skier pulls 150-200 pounds at peak.
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Old 08-13-2005, 12:13 PM
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Quote:
Originally Posted by Hoosier Bob
I would bet higher than 200. MAybe not every day Joe but tourney guys for sure. I will let you know as I have one of those Zebco fish scales and a cousin I call the "Test Monkey!" He will do anything. I think the scale will explode but that is his problem!
I can guarantee you there is WAY more pull than 200lbs. Theres more than that pulling them out of the water. If you use a 200lbs+ scale please wrap it up REALLY tight in a towel and put tape around it so when it explodes and springs go flying the driver doesn't end up with a spring hanging out of the side of his head!!
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