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Carving in deep powder

 Poster: A snowHead
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Like the skiers you see in Warren Miller films doing long, fast, sweeping carves in deep powder in the big mountains of Alaska.

Has anyone tried carving in really deep snow? Is it a bit like water-skiing perhaps?
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IMHO, They aren't "carving". When skiing deep, soft powder, the edges of your skis will have little effect, it is more to do with the bases. Turning on powder uses the resistance of the snow on the bases to make the turn, so a bigger base area will make skiing powder easier, as you get both more float, and more turning ability. This is why boarders find it easier to ski powder, than someone on skis.
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What is carving ? I pretty much agree with what you say WTFH, but is the use of the snow's resistance to get the skis to reverse camber not a form of carving? I have heard it being called soft carving. I guess it's down to semantics in the end.
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Carving technique is, indeed, applied to deep snow because the skis cannot skid.
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David Goldsmith, perhaps, but it is not carving using your edges, instead it is using your bases
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There's an article on the PSIA website on deep powder techniques-it's a bit long, so I guess it's best if you read it at work- with a section on carving the stuff.

But frankly, if most of us were given the oportunity to ski a steep and deep pitch with a 1000m of vertical, we would want to put in more than 6 or 7 turns!
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Suoerb article Kit - but I'm reading at home after a bottle of SA Pinotage and can't see any reference to 1000m of vertical - is it me?
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Kit Wong, as Alan says: suoerb (superb?) article.
I don't know about Carving in Deep Powder.
I am still at the Surviving in Deep Powder stage.
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what's happened to my p's? - must be the Pinotage Laughing
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Sorry Alan. The 1000m vertical refers to the Warren Miller boys in my first post taking for granted what we normally dream of.
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Kit Wong wrote:
What is carving ? I pretty much agree with what you say WTFH, but is the use of the snow's resistance to get the skis to reverse camber not a form of carving? I have heard it being called soft carving. I guess it's down to semantics in the end.


You raise an interesting question. It’s a complicated issue and I don't believe there is a generally accepted definition for carving in soft snow.
In previous posts in this thread, people have suggested:

1) “…is the use of the snow's resistance to get the skis to reverse camber not a form of carving…”,

2) “Carving technique is, indeed, applied to deep snow because the skis cannot skid…”,

3) “…it is not carving using your edges, instead it is using your bases”

IMHO, these are relevant comments, but don’t get to the heart of the matter.

My personal definition of carving is that at all positions along the base of the ski, the snow is moving by underneath the ski in a front-to-back direction, not at a sideways angle.

This definition works for hard snow situations (i.e., carving on your edges), as well as in soft snow situations (i.e., carving on your bases). It effectively defines skidding (i.e., the ski is moving over or through the snow sideways), and is compatible with the sometimes heard, “zero angle of attack” definition of carving (i.e., your skis are pointed in the same direction that your center of mass is moving).

By concentrating on the presence or absence of sideways motion, the above definition correctly ignores the compression of the snow under the skis bases when defining “carving” in soft snow. Other definitions don’t do this. For example, one hard snow definition that is sometimes carried over to soft snow is that corresponding parts of the ski all pass over the same patch of snow (or over the same point in space). This comes from the fact that on hard snow, all points along the edge of a ski in a perfect carve will pass over the same point on the surface of the snow.

For me, probably the most useful way to think about carving in soft snow is to imagine the behavior of a thin rod dropped into water. If the rod is straight, and is dropped into the water at any angle other than end-on, there will be sideways movement of the water by points on the rod. Clearly, this is not carving.

If the rod is curved (ie, like a decambered ski), you have a complicated situation. If it is heavy enough relative to its surface area, it may continue straight down through the water without any rotation at all. So, if it was dropped into the water with its lower end at exactly 90 deg to the surface, the flow of the water by the tip of the rod will be parallel to the long axis of the rod, but the flow of the water passing by the tail of the curved rod will be going the tail at some angle to the rod.

On the other hand, if the weight, surface area, cross-sectional shape, speed, viscosity of the liquid, and everything else is adjusted perfectly, such a curved rod will start to slowly rotate as it drops through the water, following a curved path through the water that is exactly the same shape as the curve of the rod itself. It will push the minimum amount of water out of its way and provide the most streamlined flow. While it is indeed difficult to adjust everything perfectly to make this happen, it can be done, and this is analogous to my definition of carving in powder – effectively, it’s getting your ski to leave the minimum width track through the three dimensional world of powder.

Thoughts?

Tom / PM
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Physicsman wrote:
My personal definition of carving is that at all positions along the base of the ski, the snow is moving by underneath the ski in a front-to-back direction, not at a sideways angle.


Tom,
Great comments (and I appreciate them here and on Epic), and please accept my response based on my consumption of a bottle of "Delicato" Californian Shiraz, which is quite heavy, but very drinkable...

When I think of "carving" my first thought is of carving a piece of meat. You don't carve the meat with the side of the knife, but with the edge. The edge angle, and the side of the knife help to seperate the slices, but only the edge does the actual carving.

When I think of turning in the beautiful powder found in Utah, Wyoming, and sometimes Colorado, I don't see myself as "carving" the turn, but "pressuring" it. I use my bases to turn, let them create the resistance with the snow, and not my edges.
They are very similar, and yet different actions.
Consider a 1/2 pound of butter (or similar sized cube of it).
If the butter is cold, what is the best way to to remove some of it and put it on your bread? I think it is to take a knife, and use the edge of the knife to cut through the butter, i.e. a sharp edge carving the butter.
Now take some very soft butter. If you try to carve it with the edge of your knife, the butter reforms as the knife passes through it, but if you use the side of the knife, you can push one piece far enough away to make it useable. You are using the "base" of the knife to seperate the butter. You're not "carving" it, but pressurising it apart.

Does this make sense, or have I been drinking too much?
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WTFH

I only use margarine. Does the theory still work?

Jon Smile
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spyderjon, I'm not sure.
What sort of marg?
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Nice analogy, Fox!

I agree totally with you that edges have nothing to do with ski performance in powder. However, I'm not sure if the “pressuring” part of your analogy focuses the reader on the part of the problem most relevant to making skis turn in powder.

Yes, pressing down on a ski does indeed make the ski part soft snow, but simply parting the snow doesn’t make a ski turn. For example, consider what would happen if the cross section of the ski was a tall, pointy isosceles triangle with its tip pointed down, directly under the centerline of the ski. Such a bizarre shape would still buoy you up (if it had the same projected area), and you would feel like you were pressuring it (and it was pressing back), but such a cross-sectional shape wouldn’t let the ski turn in powder.

What makes a ski turn in powder (without specific user input) is a slight differential between the force of the snow pushing upward on the front of an edged ski compared to the force pushing upwards on the rear of the ski. If the ski isn’t edged, this force differential simply makes the tip rise vertically upwards. If the ski is edged, the force differential pushes the tip in the direction of edging. When the ski is moving forward through the snow, snow is coming directly at the upwardly curved front section of the ski, so the fore-aft force differential is larger for a ski that flexes, compared to one that doesn’t.

When you think about it, a fore-aft force differential is what causes skis to turn both in powder and on hardpack. The difference is simply whether the force that the snow exerts on the ski is all concentrated at the ski’s edge, or is spread out over the entire width of the base. So, “pressuring” certainly happens on both types of snow), but a force differential is the key to any turn.

Now, once past this observation, the next interesting issue is what type of turns are available to be made. If the snow is going sideways under an edge (on hardpack) or sideways under the base (in soft snow), more drag will be generated than if the snow is passing by the ski without any L-R angle. Because this concept is identical whether the snow is hard or soft, I think it’s fair to call this type of minimum drag turn “carved” whether on a hard surface or in powder. This is the background that leads to the definition I put forth in my previous post. I’m writing fast, so I hope this explanation is adequate.

Tom / PM

PS – My previous post on carving in powder focused exclusively on coming up with a suitable definition. I thought it would be clearer if I separated any discussion of the mechanism that allows you to carve from the definition of carving. In retrospect, I probably should have put the “how-to” material of this post into my definition post, right from the start. Sorry.
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Oh dear: I am very worried: I think I might be cracking up. Sad

As young Foxy probably remembers, I have in previous posts on ski technique suggested that all this stuff on dissecting out precisely what happens when we ski was a complete waste of time: a load of pretentious hooey.
But - and this is a Big But - I have found the discourses by Physicsman and WTFH quite fascinating. Indeed I want more. (Definitely crackinig up!) I thought I understood how we turned on piste, but had never considered it might be different off piste. I now realise I didn't have a clue about either.
Gosh, this can be a humblinig site at times....
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> ...I now realise I didn't have a clue about xyz ...

Beware: Here be dragons!

Put differently, many previously normal people landed in my profession when they had similar realizations. Wink

Tom / PM
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Physicsman wrote:
The difference is simply whether the force that the snow exerts on the ski is all concentrated at the ski’s edge, or is spread out over the entire width of the base. So, “pressuring” certainly happens on both types of snow, but a force differential is the key to any turn.


Tom, thanks for the reply. I believe we are talking about the same thing, just using different words (and in my case last night, slightly inebriated ones!)
What I was trying to say, and what you said lot better than me in the paragraph I've quoted is the difference between turning using the edge of the ski, which has a very small surface area, compared with turning using the base of the ski, which is far greater.

As you say, the turn is effectively the same thing, just using different parts of the ski to enable it.
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Quite heavy Physicsman. You could reduce your sidewards movement by either tethering yourself to a length of rope like a waterskier, or to a lesser extent, mounting daggerboards to the base of your skis. Hmm, that's a thought.
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Laughing

What an sight that would be! However, you better make your daggerboards retract automatically if the skier ever hopes to put his skis flat on a packed trail. Wink

BTW, I hate to tell you, but some Maggots beat you to this idea. About a year ago, they proposed putting daggerboards on skis in a thread on Powdermag.com. I think it was in the thread on swallowtail designs. Unfortunately, since the archives were destroyed, that thread is probably gone.

Tom / PM
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Well, using daggerboards wouldn't make the snow ski more like the water skis?
Or like those waterboads that are used nowadays that have "fins" at both ends?
I think of skiing in deep snow more like waterskiing than carving.
Meseems to remember that Todd Murchison wrote somewhere that one skis into the powder not on it...
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How do the boards designed by Shane McConkey work in powder? You know the model that sort of looks like a surfboard?
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You mean the "Spatula", ie, the one with negative camber (curves up at the tip and tail) and negative sidecut (wider in the middle than ends)?

If so, here's a review that seems pretty representative:

tetongravity.com

There are some people who simply can't get past the fact that they don't carve on packed snow, but from what I hear, they sound like a complete hoot in soft snow.

The next time I run into a powder day, just for yucks, I'm going to tie a string between the tips and tails of my Explosivs, and tension it to keep them in permanent reverse camber. Maybe the experiment will give me some idea how the Spats feel. Wink

Tom / PM


Last edited by After all it is free Go on u know u want to! on Tue 11-05-04 15:48; edited 1 time in total
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Physicsman,
Quote:

(curves up at the tip and tail)
Quote:

wider in the middle than ends
Isn't that a banana?
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Exactly. Fortunately, they are not yellow. Wink

Tom / PM
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Physicsman, No, it's a pair of Pocket Rockets! Wink
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Physicsman, so how do these spatulas work - they seem to go against all I understood about how girlie-shaped skis turn. These are pot-belly skis.
Skis, Jim, but not as we know them. Please explain !
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99.99% of what you hear about how skis turn applies ONLY to turns made on a firm surface by a "normal" ski. That stuff doesn't apply to Spatulas because on a firm surface, their tips and tails are up in the air, not contacting the snow at all.

Thus, Spatulas can be pivoted easily and skid around like crazy on such surfaces (but are manageable). They are specialist skis designed for soft conditions. They turn on their bases like any other ski in soft snow.

Turning "on their bases" was described a bit in my previous messages in this thread and simply involves a difference between the force the snow is applying to the wider front half of the ski and the force being applied to the rear half of the ski by the snow. If the ski isn't edged, this force differential will simply cause the tips to rise. If the ski is edged, the force differential will have a component in the plane of the snow, and cause the tips to be pushed in the direction they are edged. Keep this up for long enough, and your skis just made a nice curved arc in the snow.

The reason for the negative camber and sidecut is to make the skis less twitchy than regular powder skis in irregular, cut-up snow. I've never tried a pair, but apparently this design works extremely well in such conditions. Obviously, they completely gave up any possibility of hard snow carving in order to get this benefit.

HTH,

Tom / PM
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David Goldsmith wrote:
Carving technique is, indeed, applied to deep snow because the skis cannot skid.


Only just seen this thread, my 2 Euro cent .....

I thought there was no such thing as the perfect carve.

Can't some very skilled ski professionals travel 'sideways' in powder as do some ##"&^$^%£!!! boarders.

Going back to the original question by Kit -
In powder speed is your friend. The faster I go the more skiing powder feels like carving on the piste. Yes (for me at least) similar to water skiing. At higher speeds the powder/water feels like a solid surface and not something you flex into and out of.
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Yup, higher speeds will make you plane higher in the powder and make it feel more like a solid interface (or at least, water skiing). The higher your skis are in the snow, the easier it is for them to do everything - pivot, skid, hop upwards, etc. More surface area on your ski bases does pretty much the same thing, AND allows you to do it at the lower speeds which might be necessary because of trail width, crowding, slope angle, etc.

And, yup, actually, most people do travel sideways in powder, at least to some extent. The most obvious way for this to happen is in a steeply banked, tight turn, where the snow is compacting under you as you go. Looking down from above the skier (perpendicular to the snow surface), this compaction of the snow appears like the skier is skidding sideways, especially when compared to the clean track left on a firm surface by a carving skier. This compaction can't be eliminated by any technique, and I don't tend to think of this as "skidding".

OTOH, if the skier isn't banked quite enough for the G-forces of the turn, there will indeed be additional sideways movement through (or over) the snow. I do think of this as "skidding" (whether in powder or on a groomer). This is probably what you were referring to.

The thing that is very difficult to do when your skis are immersed in deep heavy snow is to pivot them around the axis of your legs. When you can't pivot them at all, but you can edge them adequately (eg, by banking into the turn), the resulting turn is what I would call a carved turn (in powder).

Finally, I will agree with you that there is no more of a perfect carve made by a skier, any more than there is a perfect circle on paper made by a person. There are, however, both theoretically perfect circles and theoretically perfect carves to which we can aspire.

Tom / PM
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I've come rather late to this thread, Wear The Fox Hat, but your warm butter analogy sounds like a complete skid with no carve. (I wanted to check it full-scale but couldn't find a large enough butter-pat for my skis.)

Titian, in the famous anecdote, is supposed to have drawn a perfect freehand circle to show his skill to the emperor via the messenger who had asked for a sample of his work.
Does an anecdotal perfect circle count as a theoretical one?

I don't know why I am adding to this thread since it is obviously written-out. Another example of me talking to myself, I'm afraid. Mumble mumble mumble.....
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snowball, hello, this is doctor Fraiser Crane, I'm listening...
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No, it's in your anorak hood Madeye-Smiley
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Bye, bye till later, folks.
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I attended a concert last fall by a group called the Watercarver's Guild. I think a good powder skier is a watercarver, as is a good slalom waterskier, despite claims to the contrary. There's definitely something artistic about powder skiing.
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Physicsman wrote:
Nice analogy, Fox!

<snip>

What makes a ski turn in powder (without specific user input) is a slight differential between the force of the snow pushing upward on the front of an edged ski compared to the force pushing upwards on the rear of the ski. If the ski isn’t edged, this force differential simply makes the tip rise vertically upwards. If the ski is edged, the force differential pushes the tip in the direction of edging. When the ski is moving forward through the snow, snow is coming directly at the upwardly curved front section of the ski, so the fore-aft force differential is larger for a ski that flexes, compared to one that doesn’t.
<snip
.


I have slight understanding trouble with the above paragraph, PM. It sounds as though you're describing turning about foot center (requiring ankle flexion). How do you resolve this differential into a net force directed into the center of the arc?
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Hi Comprex. Good to see you over here. With Epic still down, I'm starting to feel like we are in the midst of an epic diaspora.

Yup, you are absolutely correct - I omitted a critical linkage in my logic. Thanks for pointing it out.

The net force that the snow exerts perpendicular to the base of the ski pushes the ski upwards when the ski is flat, and pushes the ski to the side when it is edged. This is necessary, but not sufficient for a turn to continue. In addition to pushing sideways, the tip of the ski must continue to rotate in the direction of the turn as the turn progresses.

One way to accomplish this is for the skier to provide an adequate rotatary torque. This will work even on a pair of 2x4's (ie, straight skis with essentially infinite sidecut radius). If the skier provides too much torque, the tails will skid out. If the skier provides not enough, the turn will stop, even though the ski might still be edged (note: still talking about powder conditions).

A second way to accomplish this is for the ski itself to provide this rotary torque. This is what the force differential that I was talking about in my previous post provides. The extra force on the tip compared to the tail is (as you point out) a torque, and it keeps the turn going automatically, even with no torque provided by the skier's leg.

Sorry about not giving a complete explanation in the previous post. I try to avoid being too wordy and sometimes I omit a critical piece of the puzzle. Thanks again for pointing this out. I hope this didn't confuse anyone.

Tom / PM


PS - Comprex - because Epic's private messaging system is down, would you send me a regular email at physicsmanDELETE000 AT DELETEyahoo.com. It looks like we will soon be neighbors - I just accepted a senior faculty position near you & will start in June. We should have lunch someday.

PS#2 - For those of you that don't know him, Comprex is extremely knowledgable about many aspects of skiing, particularly, the physics & mechanics of it. He undoubtedly knew the answer to this question perfectly well but is too courteous to just jump in and tell me, "Yo, dood - you missed the important part. Here's what you should have told them ...". Very Happy
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snowHead Welcome comprex! snowHead , Hope you stay around even when Epic is back up and running......
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Welcome to snowHeads comprex snowHead

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