Slalom Course Redesign - a thread for those suffering from B.R.D.S.

HortonHorton Posts: 27,143 Administrator
edited December 2014 in Technique & Theory
It is that time of year where many of our minds wander into the "Wacky Zone". Maybe is it the B.R.D.S. talking (Buoy Rounding Deficiency Syndrome - pronounced "Birds")

Based on comments that @JimBrake made in another thread @AdamCord‌ and I were talking the other day about a wider course. I think that if the balls were 10 feet wider I could run 15 off*. Balls at 47.5 feet from center and 60 feet of rope. That is 12.5 feet to spare. It would be a challenge but how hard could it really be?

@AdamCord‌ tried to tell me that if the balls were only 18 inches wider I would struggle to run a pass. As usual @AdamCord‌ must be wrong for me to be right.

(* I would not bet very much on this)

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Comments

  • klindyklindy Posts: 2,247 Mega Baller
    For what its worth I agree with @AdamCord. If the course was 10' wider you'd look like you were skiing in a cable course pulling quite long after the second wake. Likewise, if you made the course 10' wider you'd need to make the course proportionately longer as well.

    Either way drop some buoys in that new lake of yours and grab a video camera! If nothing else, it will be entertaining!
    Keith Lindemulder
    AWSA Vice President
    AWSA Southern Region EVP
  • 6balls6balls Posts: 5,031 ★★★Triple Panda Award Recipient ★★★
    Only if lengthened as well, just 10 feet wider no chance.
    Dave Ross--die cancer die
  • Than_BoganThan_Bogan Posts: 6,346 Mega Baller
    Interesting. Firstly, width is a much bigger deal than rope length. Dr. Jim helped demonstrate that, but it's also clear (ish) from the geometry: 5 feet less width decreases the required rope angle more than 5 feet of extra rope does. (Until they meet when both require the full 90 degrees.)

    So if the course is 10 feet wider, -28 is gonna be harder than -38 is now. But -15 is probably still pretty doable after getting acclimated. From a combination of science and pulling stuff out of my ass, I think it would be harder than -32 and easier than -35.

    Try it and let us know how our predictions were!!
    Nathaniel Bogan -- GUT Padawan
  • bowtybowty Posts: 75 Baller
    What if we add more buoys?
  • 6balls6balls Posts: 5,031 ★★★Triple Panda Award Recipient ★★★
    @than_bogan I'm no engineer but agree by seat of the pants. One of the courses I ski is a squeak narrow. It's hard to measure it accurately to see how much given how a person has to measure...but it's pretty close.

    That course is duck soup to ski. I don't miss 38 there and 35 feels like 32 (only easier). A ski partner who runs most of his 35's by season end but one in a zillion 38's makes 38 there. If I was given a half foot of extra rope, I don't think it gets that easy. I have had legit shots at getting out of 39 on that course...that doesn't happen anywhere else and again...give me a half foot or foot of rope and that doesn't happen.
    Dave Ross--die cancer die
  • Jody_SealJody_Seal Posts: 2,629 Mega Baller
    The answer is not to widen the course at all but rather enter course right to left after every completed line length. Most sites (except sites with the pesky jump in the way) currently would be able to accommodate a 12 buoy opposite course. run 28 from left to right then right to left before shortening!!
    Hobby Boats can be expensive when the hobbyist is limited on their own skill and expertise.


    crashmanJJVDMZN
  • EdbrazilEdbrazil Posts: 1,396 Historical Baller

    Dr. Jim's course, in "narrow mode" was about 2 1/2 feet narrow on each side. And, he was
    running 41 on it at "record" tournaments. I expect that amount was worth 2+ passes.
    Would be EZ to check out on a modified crosslined course with some high-level Open skiers,
    both Men and Women.

    I had a friend, who was not a deep shortline skier, run thru at least 41 on the INT "inner"
    course, which is 4 meters (about 13 feet) narrower each side. Was apparently ridiculously EZ.

    In the wider direction:
    Back in 1964, at his ski school in Sarasota, he had one course that was just one foot wide on
    each side, which he described as a bitch of a course. At that time, he was occasionally clearing
    24 off and getting into 30 off at tournaments.

    10 feet wider each side would make the course nigh unto impossible for beginners.

    Note: Chet Raley has the Left-Hand course option at his ski school operation in Boca Raton.
  • EdbrazilEdbrazil Posts: 1,396 Historical Baller
    Note: that was Joe Cash in Sarasota.
  • gregygregy Posts: 2,544 Mega Baller
    I was at a clinic with Wade Cox and he had someone go through the coarse opposite.
  • RazorRoss3RazorRoss3 Posts: 1,327 Mega Baller
    There is an obscene amount of time at -15 but I'm not sure I could do it at 34, in face 38mph may be required in order to carry speed out to the wider buoy. I'm not sure a longer course is necessary but in terms of width it will feel like skiing -28 but moving a lot farther. So maybe yes to the longer course... More variables than I think o can accurately account for.
  • IheartJumpIheartJump Posts: 41 Baller
    interesting to think about:

    shortening the rope doesn't necessarily change the distance you have to cover in the same amount of time; but making the course wider does.

    by making the course 1 foot wider, you have to go out 1 foot wider at 1 ball, come back from 1 foot wider at 1 ball and then back 1 foot wider at 2 ball etc.

    shortening the rope only increases the angle of the pull of the boat (i.e. the boat is pulling you harder back to center at shorter lengths)

    by making the course wider (but not longer) you actually have more ground to cover in the same amount of time, meaning your average speed has to increase.

    with a shorter rope, you still have the same distance to cover in the same amount of time (same average speed), but you need to do more work behind the boat to get free and make it out to the buoys before you're pulled back in.

    ** this is under the assumption that the skier path for 15 off is the same as 41 off. which we know isn't exactly true
    Horton
  • IheartJumpIheartJump Posts: 41 Baller
    just did a little trig because this sparked my interest.
    @boat speed 36 mph, if a skier followed the straight line path from buoy to buoy he would travel 293.75 meters in 16.08 seconds = 40.86 mph
    if you make those buoys 10 feet wider, the skier travels 312.74 meters in 16.08 seconds = 43.51 mph.

    so maybe it won't feel so much like the rope is shorter, but that you're going super fast!

    iwsf.com/rules2004/rulebook2004/diag04a.gif
  • AdamCordAdamCord Posts: 701 Open or 55K Rated Skier
    @Horton are you really bored or something?

    The one time I tried a course that had mistakenly been installed with the turn buoys ~1.5 feet too wide, neither @adamhcaldwell or I could manage to run 28off on it. If we had had a longer rope we would have tried it. We found that we could get the ski outside of the ball, but there just wasn't enough speed/energy to carry you back to the line. Maybe with some serious practice and a different ski setup it can be done, but NO ONE is running a pass at 15off with the buoys set 10' wide.

    If you stretched the course and used a ski that had insanely low drag, like a trick ski, it might be possible.

    I also once tried a course where the buoys were I think ~4 feet narrow. Running 43off was easier than 15off on a normal course.
  • NandoNando Posts: 480 Crazy Baller
    Over the years there has been some occasional discussion about very short line being unfair to shorter skiers. One thought other than messing with the width of the course to change things up would be to keep the width as-is and reduce the distance between buoys from 41M to 40M- that might make things interesting...
  • buoyboy1buoyboy1 Posts: 70 Baller
    Many years ago back in Ohio I skied on a portable course on a river and was able to get 3 @ 35 off. At that time I could barely run 15 off at 34 mph. We measured the course arms when we got done skiing and the turn balls were 16" narrow on each side. Course width makes MUCH more of a difference than the length of the rope. I sure miss that course......:)
  • buoyboy1buoyboy1 Posts: 70 Baller
    Typo, I meant to say 3 @ 32 off......
  • 6balls6balls Posts: 5,031 ★★★Triple Panda Award Recipient ★★★
    edited December 2014
    Holy crap the Dr. Jim thing was 2.5 feet per side meaning 5 feet narrower overall??? That's nuts. I can post WR big score on that one and the pro's?...ridiculous.
    Dave Ross--die cancer die
  • HortonHorton Posts: 27,143 Administrator
    When I first mentioned this to @AdamCord‌ he gave me some crap answer about how who ever designed the course must have spent a long time thinking about it. @Edbrazil‌ will correct me but I assume it was semi random. A standard rope was 75 feet long and the balls were originally exactly 1/2 that wide. (37.5 x 2 = 75 for this of you in Minnesota).

    I have trouble finding the time to try this kind of wacky crap but I really want to.

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  • Ed_ObermeierEd_Obermeier Posts: 1,339 Crazy Baller
    FWIW I'd vote for adding a couple more buoys. That or adding buoys on the opposite side per @Jody_Seal's post above. A lot of private sites probably couldn't accommodate another couple balls longer but an opposing course would be relatively simple to do.
    Ed Obermeier - owner, EZ-Slalom Course Systems
    www.ez-slalom.com
  • Than_BoganThan_Bogan Posts: 6,346 Mega Baller
    Aha! The Adams cheated by actually trying it! :) Interesting results. I can definitely believe that a very different ski design would be needed for even a little more buoy width.

    Btw, Yoda with caliper is the coolest icon EVER.
    Nathaniel Bogan -- GUT Padawan
  • thagerthager Posts: 4,424 Mega Baller
    @Horton Thanks for explaining that to us in Minnesota. Don't you have a tree or something to hug?
    Stir vigorously then leave!
  • HortonHorton Posts: 27,143 Administrator
    @thager‌ did you just call me a tree hugger? Do you know what I do for a living? "Drill Baby! Drill!"

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    kstateskier
  • thagerthager Posts: 4,424 Mega Baller
    Yep, And I bet you are a closet Demoncrat too!!
    Stir vigorously then leave!
  • thagerthager Posts: 4,424 Mega Baller
    I am pretty sure I have the BRDS Flu. Went to buy "holiday" gifts today and spent 20 minutes at a sports store staring at waterski stuff. I think I was drooling too.
    Stir vigorously then leave!
    schafer
  • drewdrew Posts: 75 Open or 55K Rated Skier
    I would like to see the course dimension of 11.5m from centerline changed to 12m, all else equal.
  • HortonHorton Posts: 27,143 Administrator
    @drew It is not super cold at your house. Drop in some balls and get us some video. It will give you an excuse to show off your pretty green ski.

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  • Chef23Chef23 Posts: 5,887 Mega Baller
    Does making the course wider change the fact that as the rope get shorter being tall is an advantage. It doesn't seem to me that it does.
    Mark Shaffer
  • HortonHorton Posts: 27,143 Administrator
    @Chef23‌ the fun part of a thought experiment like this is we really do not know any of the answers.

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  • HortonHorton Posts: 27,143 Administrator
    What I do love about this thread is the comments about how 6 inchs of width on the balls can totally change scores. Brings me back to another thread...

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  • MattPMattP Posts: 5,979 Mega Baller
    I remember hearing a comment that @Mapple made about how running 41 is easier now than when he did it the first time because the buoy tolerances have gotten smaller thus moving the course in. If I remember the rule book correctly the course is measured to the middle of the buoy and not to the outside edge so the distance we think we are traveling is actually less than what we have to travel to get around the buoy. @Edbrazil‌ I'm sure would know the exact numbers
    Horton

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