Base carving

Discussion in 'Ski School' started by François Pugh, Jan 7, 2019.

  1. François Pugh

    François Pugh Out on the slopes Skier

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    A spin off from the carving on hard snow thread: "Carving" in soft snow using the entire base of the ski as your "edge". The ski base, starting with the tip creates a layer of compressed snow "under" it, upon which the ski rides. There is no hard layer that the entire ski edge gets pressed onto (and ever so slightly into); the edge at the widest part of the tip is free to extend farther from centre-line than the mid-ski under-boot edge; you are liberated from R = Rsc * Cosine (theta). Still, shape plays a role as surface area times pressure affects the force on the ski, which is bent according to the force and stiffness of the ski.

    You can traverse with fairly clean tracks in a straight line!

    You can feel like you are carving a smooth turn, until you try to turn too tight and the snow platform you created beneath you breaks away, and you are drifting like a water skier.

    On the other hand tip the skis too far over and you're on your digging your way to China.

    What does it take to "base carve" clean turns?
    1. Correct shape and flex for speed and snow conditions.
    2. .....

    @LiquidFeet ?
     
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  2. geepers

    geepers Getting on the lift Skier

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    Interesting post. Two small points.

    1. We should use plural - as in skis - since we can use both of 'em.

    2. wrt the quote above...
    Not quite - if I understand it correctly. It seems that the tip begins to compress the snow and the length of the ski following behind further compresses the snow until such time as a platform (about when the boot comes along) is created to support (and turn) the skier.

    [​IMG]

    From https://www.sciencedirect.com/science/article/pii/S1877705810003395

    So the tip cannot extend outside the centerline of the curve it is helping create - otherwise it would compress the snow out of the way and we wouldn't have a platform to support the ski = no turn.
     
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  3. Thread Starter
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    François Pugh

    François Pugh Out on the slopes Skier

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    Think deeper snow, with the entire base of the ski riding on the snow. The narrow under-boot sections travel upon the middle of the platform created by the skis's wider tips. Think skiing straight, then think in a turn with skis tipped, but still in the snow.
     
  4. Mike King

    Mike King AKA Habacomike Instructor

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    In bottomless pow, I don't think side cut has much to do with it. It's all about bending the ski. Feel free to tell me why that isn't so....

    Mike
     
  5. James

    James Making fresh tracks Instructor

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    One would hope the middle of the ski was wider than the boot or it won't work too well?
     


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    François Pugh

    François Pugh Out on the slopes Skier

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    Given the same stiffness, a ski with a wider tip and tail will bend more because there is more pressure times area at the tip and tail bending the ski, so shape does matter in bottomless powder or other deep soft (soft enough that the whole ski sinks in and not just a quarter inch of edge ) snow.

    Think of the ski as an upside-down beam supported by a single post at the boot and with a uniform snow loading (imagine it supporting 6 feet of snow applying pressure to bend the beam/ski).
     
  7. Rod9301

    Rod9301 Getting off the lift Skier

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    True, but i still like skis without a lot of sidecut in powder.
     
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  8. HardDaysNight

    HardDaysNight Getting off the lift Skier

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    It is so. However, ski shape does to some extent influence how easily the ski can be bent. To make it really easy get a fully rockered , prebent ski:duck:
     
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  9. Wilhelmson

    Wilhelmson Getting off the lift Skier

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    * This could be more of a ramble than a lucid contribution.

    In the other thread there was mention of applying the proper amount of forward/aft pressure to maintain the clean arc. I'm not a great carver but in soft snow it's the same but different Maybe the inside ski is doing a little more work since over pressuring the outside ski would push it into the snow. It seems a light tipping of the ski is all it takes sometimes, of course on steeper stuff in the woods out of caution I"m probably overturning a lot more than I remember. Here in the northeast when you dig the ski into the snow you find lots of goodies like ice crust, rocks, and downed limbs.

    Not sure what I'm doing here but the outside ski is dug in pretty good. I was staying ahead of my family to look out for the 4 foot river gullies.

    1.jpg


    Smoother but relatively wider skis and not as steep.

    2.jpg
     
  10. Rod9301

    Rod9301 Getting off the lift Skier

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    Snow plow and back seat?
     
  11. James

    James Making fresh tracks Instructor

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    IMG_5774.JPG
    Assume that's your son?
    Use line to control speed. Consider shorter poles.
     
  12. Wilhelmson

    Wilhelmson Getting off the lift Skier

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    Definitely back seat, even for a foot of snow. Snowplowise that's what I first thought but I think you would see it in the tracks.Also the left ski looks flat, whereas the right ski is tipping (or skidplowing) into the turn. I think the left ski would be tipped if in snowplow. Hard to tell with one picture.
     
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    François Pugh

    François Pugh Out on the slopes Skier

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    It's not so bad.

    He's at the end of a turn, and bringing the skis together, maybe a bit of a residual a-frame. Or maybe, like many recent learners, he spent too much time skiing in a wedge and still has a remnant thereof.
    Backseat? Maybe he's forcing his tips up (no need to do that)

    Anyway nobody asked for detailed MA. I only piped up in response to other posters comments. He's skiing and riding the bases. That's what counts.
     
  14. Wilhelmson

    Wilhelmson Getting off the lift Skier

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    That's cool. I had some recent pictures so figured I'd show me digging my ski in and my kid staying on top of the snow. Always something to learn, even from a single picture. I found a video of him in the woods where he used a similar right ski brush or whatever you call it before jumping off a steep section. I'll have to watch him more closely in the moguls, but in general there's no classic snowplow left in his style. Not needed in the the picture, but I suppose a pivot would be a more technically correct speed check. I've seen racers snowplow down to the the start gates plenty of times.

    Neither turn is perfect, mine shows that putting too much pressure on the outside ski causes it to sink whereas my kid was too far back which lifted the tip of the inside ski and caused the outside tail to skid out slightly. I was probably overturning to avoid following the snowboard track to the right and was going to hold that line through the open section to the left.
     
    Last edited: Jan 10, 2019 at 7:02 AM
  15. Chef23

    Chef23 Putting on skis Skier

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    @Wilhelmson those conditions look sweet. I haven’t seen conditions like that in years. Have fun with your kids.
     
  16. karlo

    karlo Out on the slopes Skier

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    I do not understand the physics of it, but if I understand the what the OP is referring to, then short turn base carves in steep deep powder results in lots of powder flying in every direction, flying behind you, to either side, and when sufficiently steep, deep, and fast, huge plumes flying into your face. The only time I’ve had such an opportunity, I pulled up, having felt a bit of claustrophobia. But, the interesting thing is that one can emulate exactly the same movement patterns on lightly packed powder or wind blown. The result is what I’ve previously described as being in a warp field, incredibly quiet and tranquil inside, incredibly turbulent outside. To accomplish such in less than deep powder, pretend and imagine one is in a field of such powder, do as one would do in such powder, and wow! Base carving, if I understand it correctly, is very dynamic skiing that, yes, bends the ski. And every turn is a blast, a blast of snow.
     
  17. Josh Matta

    Josh Matta Making fresh tracks Instructor

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    curious ghost is there base carving going on here?

     
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    François Pugh

    François Pugh Out on the slopes Skier

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    ^^^Looks like it.^^^
    I was thinking of fewer, but longer and longer-sustained turns causing more change of direction, but video above looks like quickly alternating left and right turns that are made by pressuring the bases of curved skis riding on the snow the skis are compressing.
     
  19. Dakine

    Dakine Getting off the lift Skier

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    In deep snow, skiing has more to do with hydrodynamics than mechanics.
    Once you get going fast enough to get on plane, the edges of the ski have little to do with what happens.
    It is all about shape and pressure distribution.
     
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  20. mdf

    mdf back to being an ordinary Gatheree Skier

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    I'm not sure if this is a vote for or against the "base carving" concept. I'm a firm supporter. I invoked a similar concept a few years ago (maybe on Epic) when complaining about how "vague" the Soul 7 was. I said it didn't want to "carve" a path in the powder, the carve being analogous to hard snow carving. And a lot of people objected. (Maybe some of the same as here?) The point is distinguish technique and skis that like the tails to follow the tips from those that purposely smear (or those, like those Soul 7's, that just don't reliably do what you ask them to).

    We can ponder the physics behind it (compression wave? consolidated snow? a directional design that likes to stay aligned even if the feeling that the snow has memory is an illusion. That does not diminish the fact that some powder skiing feels a lot like carving.
     
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