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Towline Tension

EdbrazilEdbrazil Posts: 1,396 Historical Baller
edited December 2017 in News & Other Stuff
Anyone out there have some information to contribute, about how much towline tension a SL skier generates?
Some years back, Dave Benzel had a computer-interfaced system, that measured tension and other factors.
I did some work at times with a Dillon Force Gage. Eay back, Jim Sylvester (AWSA President, Technical Committee)
did some measurements in the 1960s.

I have heard a figure in the range of 900 lbs. max. Don't know if this is accurate; sounds like a lot.


  • A_BA_B Posts: 4,297 Mega Baller
    That system was called LISA and there was an article in Spray or WSM. 900 was the max that Andy put on the line at 39 Off right behind the boat. The plotted pull force started with deepwater starts, which also put a fair amount of load on the line.

    I am only guessing, maybe 250-300 pounds if I am remembering right. One thing that stood out was how consistently Andy peaked and where he peaked compared to some other decent non-Pro tournament skiers. There was quite an increase as all skiers headed into the wakes.

    I wanted to get a copy of that article but WSM doesn’t have back issues, and had posted the approximate date of the article before, requesting all those guys who still have stacks of old magazines to look for it.

    The only magazine I had was one where Benzel ski school was advertising to “come ski with LISA”. Not the article.

    I’d love to see the article if any Ballers can post a copy.
  • ALPJrALPJr Posts: 2,392 Mega Baller
    I think Syderhoud measured the lbs of pressure on the rope in the West Coast Slalom video with Marcus Brown and Terry Winter.
  • 6balls6balls Posts: 5,567 Mega Baller
    In college when I was stronger and skied even more improperly than I do now I used to go through about 3 straightline brand ropes/year that were tensile rated at something like 1000-1200 lbs.

    Always carried a new one in my trunk in case I skied with friends so I could give them a rope after (often) breaking theirs. Broke two in one day once and broke one at collegiate regionals. When I was a kid @razorskier1 broke three in one day--the one we were using, our spare, and the one we bought at the marina that day cuz we were out of ropes.

    My guess is with all the understanding of efficiency now the amount of line tension on top skiers may be less than before? Dunno, in any case I bet it's still a very big number.

    Dave Ross--die cancer die
  • eleeskieleeski Posts: 3,977 Infinite Pandas
    If I remember right (it was back in college - a LONG time ago), just riding a trick ski was about 75 pounds pull, the smoothest O was 150 and a sideslide was 25 pounds. Any wake trick or hard pull went off scale on our 500 pound max scale.

    Remember the Saf-T-Pop automatic trick release? With such wide variations in load, no wonder it didn't work.

    @6balls Ropes are much better nowadays. You braggart. (I'm still impressed.)

  • pregompregom Posts: 311 Baller
    I'd like to see visualizations of the pull force through a pass in the course. Maybe something like this GIFwith the rope that changes color as the load gets higher? Or a 3D plot where the x- and y- axis represent the handle path and the z-axis represents the load? and all this with real data coming from different skiers?
  • AdamCordAdamCord Posts: 899 Open or Level 9 Skier
  • JordanJordan Posts: 1,251 ★★★Triple Panda Award Recipient ★★★
    Wondering if modern skis are more efficient at turning resistance to the boat into acceleration and therefore reduce tension on the rope?
  • mwetskiermwetskier Posts: 1,337 Mega Baller
    buy borrow or steal a copy of suyderhouds ' west coast style ' instructional video. theres an entire section on video analysis of terry winter and marcus brown skiing shortline and some of the clips have a time readout and strain gauge window that give real time values of elapsed time and rope loads. that may very well be some of the most accurate and reliable data you will ever find on the subject.

  • taptap Posts: 105 Crazy Baller
    edited December 2017
    I've measured skiers anywhere from 400 to 700 lbs. force across a pretty good range of skill level. In general, the better the skier the smoother and higher the load.

    Some previously posted data.

  • mwfillmoremwfillmore Posts: 64 Baller
    Resurrecting this thread @tap @AdamCord can we see what kind of hurt @adamhcaldwell puts on pylon
  • MDB1056MDB1056 Posts: 582 Crazy Baller
    edited January 25
    Didn't they just measure that at the last couple of majors as some new stat? Thought J Travers took top slot with some ridiculous amount of pull
  • AdamCordAdamCord Posts: 899 Open or Level 9 Skier
    @mwfillmore he pulls hard but not as hard as @FWinter

  • Dacon62Dacon62 Posts: 813 Crazy Baller
    edited January 25
    Whats going on here? That is a heck of a lot of load/weight. There is no way I could hold almost a 1,000 lbs in my hands if I was standing straight up with good posture.
    In the West Coast video I recall that 400-500 lbs was the max measured range. It went up slightly with each shorter pass. How did we get to 900+ pounds. Is the way the load is measure in the post above measured differently?
    Does the boat provide some of the measured load as it moves forward. Obviously, it does provide load that is how cross course speed is generated. I guess what I am asking is only half the load amount felt by the skier because the other half of the load is taken on by the boats forward momentum?? Anyone understand what I mean?
  • elrelr Posts: 328 Mega Baller
    Interesting that 2 of the 3 scores into -41 were at the bottom of the list.
    Ed Rink - LSF Texas
  • Dacon62Dacon62 Posts: 813 Crazy Baller
    lighter guys, less swing weight I'm guessing.
  • ReallyGottaSkiReallyGottaSki Posts: 218 Baller
    edited January 25
    Yes although the raw numbers remain impressive, I'm sure it's been mentioned normalizing the measured peak force to body mass better delineates some skier efficiencies in accelerating. Also a skier maintaining less peak force but for over a longer duration can apply more total power , and if applied in the right locations, accelerates in better shape and gets to the buoy earlier.
    Also a 'save' on a turn/cut can really load the line so one would have to be certain to compare only 'normal' turns and trim the flyers for all groups, analyze what is typical before any technique and style comparisons

    @Dacon62 , I believe it's legit, the force is the same both ends of the rope, else there would be separation of the two points occuring. Their movement relative to the observer is not a factor, and the ropes mass is negligible
  • aspskiaspski Posts: 227 ★★★Triple Panda Award Recipient ★★★
    Mostly you can endure it for very brief periods of time. If it was several seconds no way, but 1000lb for 0.01 seconds the human body is capable of that. I remember seeing sports science clips showing forces of skiers and snowboarders landing large terrain park jumps. The force of landing was 2,000-3,000 lb in some cases, but only lasted for very brief period of time.
  • Than_BoganThan_Bogan Posts: 6,878 Mega Baller
    edited January 26
    It's surprisingly important how long the measurement is integrated. Otherwise, what a person would call vibration and/or "instantaneous" deformation can register as a massive peak force.

    That said, it's pretty sensible that if 500 is routine for these guys, then somewhere around double that would breifly appear during an Oh Crap Moment!

    So my hunch is the measurement interval on TWBC stats is reasonable.
    Nathaniel Bogan -- GUT Padawan
  • buoyboy1buoyboy1 Posts: 127 Baller
    I have always wondered why TWBC rewarded the highest rope tension load since it takes more skill to NOT peak ZO and try to stay as light/invisible as possible. TWBC should take the 39 off pass for men and 38 off pass for women and use the smallest load number to determine the "smoothest skier" award. I think we all are really good at spiking ZO when we are in scramble mode.
  • chrislandychrislandy Posts: 188 Solid Baller
    @buoyboy1 I think it's more that the rope sponsor can prove the tow line strength, although I did notice that towards the end of the season they changed it a bit so it wasn't just the highest tension, wasn't it highest tension "while in control" or something like that?
  • AdamCordAdamCord Posts: 899 Open or Level 9 Skier
    But I thought I was supposed to hide from Zero Off!! ;)
  • JackQJackQ Posts: 398 Open or Level 9 Skier
    I think many skiers look at this the wrong way, it is not so much peak load. It is the "area under the curve" the pull from the ball to CL, not just one point (peak). No one is going to run 39 off by just standing up after the buoy.

    The goal in my experience is to get as much angle and load at the buoy you can "comfortably" maintain to the centerline, better to have a little less than more. Typically though many skiers bite off more than they can maintain, spike line tension, ZO reacts and they get pulled up or out of position.
  • HortonHorton Posts: 30,238 Administrator
    @adamhcaldwell Here is how I see it. Tell my if you disagree.

    I want as much angle as possible and I need take enough load in the rope to maintain this angle but any load in excess of what is needed is to my detriment. Excess load in my hands at centerline diminishes my ability to stay in control after centerline.

    Assuming I leave the ball in control and in position it is generally not to my advantage to drive my upper mass farther away from the boat approaching centerline.

    ( I am not talking theoretical ideals what might work for a SUPER ELITE skier trying to run 41 or get some at 43. I am talking about the rest of us mortals. )

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  • slowslow Posts: 441 Crazy Baller
    Well said
  • RednucleusRednucleus Posts: 559 Crazy Baller
    edited January 29
    Between Adam & Horton I now have a brain ache
  • slowslow Posts: 441 Crazy Baller
    They have a lot of time on their hands
  • HortonHorton Posts: 30,238 Administrator
    @Rednucleus & @slow the conversation I'm having with Caldwell is exactly what I built this website for. This is why I'm here.

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