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# You can carve a turkey, but can you carve whipped cream?

In the recent Epic thread titled, A great picture of a PMTS lesson , Fastman suggested,

> "...You carve a turkey, you don't carve whipped cream..."

I can't resist responding, because (a) this is such a delightful turn of phrase, (b) is something I've been pondering for quite a while, and, (c) I recently responded to the same question on Snowheads.com, but the discussion never really took off.

I don't believe there is any generally accepted definition for carving in soft snow. However, I believe there is a definition (which I propose below) that encompasses both situations, is completely consistent with the usual definitions of hard snow carving, and makes sense for soft snow as well.

Clearly, carving ON a packed surface is not the same as carving IN the 3D environment of soft snow. The latter is more complicated. Soft snow both compacts under your skis as well as is displaced away to both sides of your skis (parted).

I would like to propose that carving in both hard and soft snow can be simply defined as directing the skis so that they leave the minimum width, minimum drag track through the snow.

This is equivalent to saying that the *average* motion of the snow under the ski will be in a front-to-back direction, not at any sideways angle (ie, looking down through a transparent ski with a camera mounted 90 degrees above the plane of the base of the ski).

This definition intentionally disregards any compaction of the snow. The hypothetical camera mentioned above would see compaction as snow coming directly upwards towards the base of the ski, not at some L-R angle to the centerline of the ski.

Displacement of the snow to the sides of the ski (ie, parting it) is also disregarded by this definition because snow to the right of the center line of a carving ski will be displaced to the right of the ski, and snow to the left of the center line will be displaced to the left, so that the average motion of the snow under the ski will still be straight back (ie, at zero degrees L-R relative to the center line of the ski).

A soft snow skier can orient his skis tips-up/tips-down, and tips-right/tips-left to minimize the width of his track and minimize his drag, but even at the optimal orientation, compaction and displacement of snow still occurs and contributes to the minimum drag that the skier experiences. Hence, ignoring compaction and displacement is reasonable as they are phenomena that the best skier can never eliminate.

The definition I propose is completely compatible with the usual hard snow definitions of carving, where you are carving on your edges, not your bases. Specifically, it is totally consistent with the hard snow carving definition that says, "all points on your edge will pass over the same point in the (packed) snow". It is equally compatible with the sometimes heard, “zero angle of attack” definition of hard snow carving (i.e., your skis are pointed in the same direction that your center of mass is moving), and it effectively defines skidding (i.e., the ski is moving over or through the snow sideways), both on hard snow, and in soft snow.

I believe that the concept of carving in soft snow is difficult because people try to directly use one of the hard snow definitions without modification, rather than coming up with a more general definition which encompasses both situations. For example, one hard snow definition that is sometimes attempted to be used for soft snow is that corresponding parts of the ski all pass over the same patch of snow (or over the same point in space). Obviously, this can never be true in soft snow because of the compaction and displacement phenomena mentioned above. By focusing on the presence or absence of sideways motion, the definition I propose correctly ignores these phenomena.

For me, probably one of the most useful ways to think about carving in soft snow is to imagine the behavior of a thin rod dropped into water (or whipped cream - ). 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 with minimal rotation. So, if it was dropped into the water with its lower end at exactly 90 deg to the surface of the water, the flow of the water by the tip of the rod will indeed 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 passing by the tail at some angle to the rod at that point.

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.

So, to make a long story short, I would argue that without being a Bill Clinton, if you define it correctly, you CAN indeed carve whipped cream.

Thoughts?

Tom / PM

[ May 08, 2004, 03:22 AM: Message edited by: PhysicsMan ]
PM

'The definition I propose is completely compatible with the usual hard snow definitions of carving, where you are carving on your edges, not your bases.'

Surely the carving is always done on the bases, it is a question of degree, in very hard snow not much more than the steel edge will bite but it is nevertheless the base (including the base of the edge) that does the business?

I've lifted this from the other thread:

'Is your whipped cream analogy mistaking the role of the edge in carving? Carving is done with the skibase which is why powder can be skied. The edge merely allows the base sufficent purchase on the snow.

A ski which was just a side edge, with little base edge and an open lattice where the plastic base is normally, would not ski (it would be like sharpening an ice skate to razor thinness - it wouldnt work either, it is the base that does the business)'
PM

this is indeed an epic post of yours and it deserves answers, so having gone over it again, I am giving it another one.

I like the metal rods and expect a bent arrow would do likewise. Another analogy some may find familiar is the falling leaf, its shape providing an aerofoil which moves it this way and back in the same way a skibase is deflected as it moves through snow (but without the stalling, except in bottomless Utah powder).

But I think your starting point definitions are questionable and need to be less peripheral to the essence of carving, the turing mechanism. The track is merely an outcome. I would sooner define carving as the travel of the ski resulting from its shape and how it moves most efficiently, it could be a straight carve as in a traverse, but once the ski is bent it would be the following of that shape.

Now while graphically the side view of the curve of the ski (seen edge on) may predict shape of the curve, it is in the plane of the base that the critical interaction with the snow takes place which is why zero sidecut skis can carve.

Whether on hard snow or in powder the mechanism is identical, namely the deflection of a curved base along a deflecting path (on hard snow it may only be a small proportion of the base, even only the base of the edge itself, but always the base, although that edge may be vital in gaining purchase on hard surfaces).

So I agree, the carver can have the cream and the turkey.
Quote:
 Originally posted by daslider:...PM 'The definition I propose is completely compatible with the usual hard snow definitions of carving, where you are carving on your edges, not your bases.' Surely the carving is always done on the bases, it is a question of degree, in very hard snow not much more than the steel edge will bite but it is nevertheless the base (including the base of the edge) that does the business?...

I have absolutely no argument with this first comment of yours. When I said "edges", I indeed meant "the base surface of the edges", not the "side surface of the edges".

I always worry about my technical posts being overly dense and opaque. So, I try to minimize the use of longer, but more accurate phrases by using shorthand like "edges" whenever I think the meaning will be clear to most people.
--------

Quote:
 Originally posted by daslider:...and need to be less peripheral to the essence of carving, the turing mechanism. The track is merely an outcome. I would sooner define carving as the travel of the ski resulting from its shape and how it moves most efficiently...
The definition I proposed was: "Carving in both hard and soft snow can be simply defined as directing the skis so that they leave a minimum-width, minimum-drag track through the snow."

At the most fundamental level, I would rather that a definition for something like carving be purely outcome based (ie, "minimum drag") whenever possible, and leave the "how do you do it" part to separate discussions of technique.

In my definition, I intentionally did not include any mention of a specific turning mechanism (eg, sidecut, longitudinal flex, differential forces on the front and back of the ski, etc.) because, in my experience, when you attempt to define something by "how you do it", you will almost always leave out somebody's favorite technique, or a mechanism appropriate to a situation you hadn't specifically considered, and this will flaw your entire definition.

Once past this, it would appear that our definitions are fairly close, with the exception that you leave out the human part, my "directing the skis" phrase, and instead, emphasize the importance of the ski shape.

I didn't explicitly mention the shape because, in addition to it being a "how" (discussed above), to me, the shape is essentially "a given" for a particular skiing situation. IMHO, the act of carving is more about how a skier uses his skis to most efficiently proceed down the mountain, and that is why I emphasized the skier's input (ie, "directing the skis"), but made the gold standard for carving something related to an outcome that could in principle be quantified, ie, minimum track width or minimum drag.

Without an explicit emphasis on "directing the skis", I would be worried that defining carving by "the travel of the ski resulting from its shape and how it moves most efficiently" might allow one to conclude that the refrigerator mounted on shaped/flexing skis heading straight down the hill at a SpringFest event was doing a great job of carving.

Tom / PM

[ May 09, 2004, 03:55 AM: Message edited by: PhysicsMan ]
Agree with much of this PM. By ski shape I mean the shape the ski assumes rather than its munufactured shape specifically, hence the remark about zero sidecut, this is the shape given it by the skier so we concurr here.

However I am still puzzled by your insistence that carving on hard and soft snows is essentially different, whereas I would say they are essentially the same. You do not carve on your edge, you carve on your base using more or less of it as conditions demand. The sharpened edge provides the purchase where necessary.
>...I am still puzzled by your insistence that carving on hard and soft snows is essentially different, whereas I would say they are essentially the same...

Actually, I would also say that they are essentially the same. That is, in fact, the fundamental reason why I started this thread and is what is behind the common definition I offered.

I don't see where I "insisted" that they were essentially different.

About the closest statement I can find is my paragraph:

> "...Clearly, carving ON a packed surface is not the same as carving IN the 3D environment of
> soft snow. The latter is more complicated. Soft snow both compacts under your skis as well as is
> displaced away to both sides of your skis (parted). ...

In it, I do claim that they are not the same. I claim "more complicated" and give a couple of examples, but I certainly don't claim that they are "essentially different". Is this the remark of mine that you were referring to?

Tom / PM
PM

'The definition I propose is completely compatible with the usual hard snow definitions of carving, where you are carving on your edges, not your bases.'

Perhaps I presumed your 'compatibility' with this bit of nonsense meant your endorsement of it. 'not your bases' sounded like your qualification remark rather than part of an erroneous definition. Sorry if I've misunderstood.

Your defn : 'I would like to propose that carving in both hard and soft snow can be simply defined as directing the skis so that they leave the minimum width, minimum drag track through the snow.'

This seems to me as being in need of more intent and less result. After all the Jetfighter's purpose is not to leave jet trails. Without any reference to turning, your perfect carve would be a straight schuss.
Surely, any snow where you can leave a track ("carve trenches") is being compacted and displaced to a certain extent? I may be stating the obvious here, but this is not an either/or situation of hard or soft snow, rather a long continuum from boilerplate through to "bottomless".
Martin Bell:
> ...this is not an either/or situation of hard or soft snow, rather a long continuum from boilerplate through to "bottomless".

Exactly. Because of this continuum, I'm trying to construct a definition of carving that will be reasonable at any depth or softness of snow.

Tom / PM
How about "Disturbing the minimum amount of snow necessary to change direction in a controlled manner"
SJ's definition is good - how does it differ from "trying to leave as narrow a track as possible"? - except that it deals with three dimensions instead of two.
Martin,
It's taken me a while to come up with this one, but I thought about it in light of previous discussions on here about why we turn. The conclusion, if I remember correctly was "I turn because I want to go over there". So, I guess the perfect carve turn must involve a change of direction and control.

Oh, and welcome to Epic!

### Some earlier definitions

Quote:
 "Carving in both hard and soft snow can be simply defined as directing the skis so that they leave a minimum-width, minimum-drag track through the snow."
--PM, 2004

Quote:
 "Pure carving utilizes the mechanics of the ski design to turn with a minimum of skidding. With increasing skill, sensitivity and subtleness, a skier is able to exploit the ski design more and more."
-- Horst Abraham, Skiing Right, 1983

Quote:
 "Carving: The skis, traveling forward through the arc of the turn, where the tails follow the same path as the tips of the skis."
US Skiing, Alpine Athlete Competencies, 1997

I notice there's nothing in the earlier definitions about snow conditions. What do you infer from that?
Even as late as 1997, there were shaped skis that would carve easily, and fat skis that would float easily, but no shaped fat skis, so it wasn't particularly easy to carve through powder. Hence the omission in the '97 quote?
Hi PM, Fastman here.

I have no problem with your definition for carving. It provides a broad spectrum description that leaves plenty of wiggle room to incorporate the concept of tracking turns with the minimum tip/tail divergence through all varieties of snow. Perhaps your definition is what's required to identify what it is we're truly attempting to accomplish, regardless of the medium we encounter. Perhaps carving is in essence simply the ability to control line with the least muscular input, to utilize the shape and mechanics of the ski, to flow with the mountain, to harmonize natures forces? This can be done in any environment.

My whipped cream analogy was sensory based. In theory I fully support your position that carving, by your definition, can be done through fluff, mush or slush, as well as on hard packed. However, in execution the sensations are so polar they almost scream to be recognized as individual entities.

When I carve on hard packed snow I'm immersed in feelings of control, balance, platform consistency and strength, line precision, track cleanness, efficiency, economy of energy. It's reminiscent of driving a highly refined sports car through a series of S turns. I feel like I'm locked in the arc and in complete control.

When I carve through deep snow I feel a contrasting loss of precision. The sensation of snow contact is vague and the platform the ski compacts and rides is inconsistent and unreliable. Build too much force and it breaks away, it lacks integrity. This creates an environment in which the turn radius is susceptible to sudden unintended changes, and constant adjustments must be made to compensate for this inconsistent medium. Snow is being plowed and displaced which requires balance adjustments that disallow true through the foot balance platforms to be consistently maintained. In contrast to the hard snow sports car feeling, this is more reminiscent of driving a tractor through a muddy field.

While a tractor can be driven skillfully through a mucky field it will never feel like my lotus on dry pavement.
Quote:
 Originally Posted by Rick When I carve through deep snow I feel a contrasting loss of precision. The sensation of snow contact is vague and the platform the ski compacts and rides is inconsistent and unreliable. Build too much force and it breaks away, it lacks integrity. This creates an environment in which the turn radius is susceptible to sudden unintended changes, and constant adjustments must be made to compensate for this inconsistent medium. Snow is being plowed and displaced which requires balance adjustments that disallow true through the foot balance platforms to be consistently maintained. In contrast to the hard snow sports car feeling, this is more reminiscent of driving a tractor through a muddy field. While a tractor can be driven skillfully through a mucky field it will never feel like my lotus on dry pavement.
Thanks - now can you please send me that in a poster so I don't have to keep explaining to people why ice is MASSES easier for me to ski than deep soft snow

I'll add the motor control & feedback stuff (unless you want to)

### Snow specs

Martin, I believe the earlier definitions did not specify the snow conditions because the authors did not think that carving was something we do on hardpack alone. I think the notion that carving can only occur on hardpack is of fairly recent vintage.

A carving ski is tracking forward with very little sideways drift. Sometimes a skier wants to add some sideways drift for one reason or another. The point is not whether a skier can carve, but whether the skier can fully employ the ski's design.
The notion that carving can occur in deep powder is also of fairly recent vintage. Ski films were pretty much full of skiers using bouncy short turns in the deep stuff until Nobis started carving big SG turns down Alaskan faces. Fat skis weren't essential but they gave him and the likes of McConkey the confidence to ski that way. Of course, the sideways standing fraternity were ahead of the 2-plankers when it came to arcing long turns in powder...

### More Definitions of Carving

Quote:
 A turning of the skis with little lateral movement of the skis over the snow.
--ATM, Teaching Concepts, 1980 (Horst Abraham)

Quote:
 A turning of the skis with little lateral movement of the skis over the snow.
--ATS, Strategies for Teaching, 1987

I take back what I said about the old definitions--over the snow is different from in the snow. I agree with you, Martin, that the snowboarders showed skiers and ski designers how to expand the definition of carving.
Quote:
 Originally Posted by Wear The Fox Hat Martin, It's taken me a while to come up with this one, but I thought about it in light of previous discussions on here about why we turn. The conclusion, if I remember correctly was "I turn because I want to go over there". So, I guess the perfect carve turn must involve a change of direction and control. Oh, and welcome to Epic!
How's tricks, SJ? Thanks for the welcome message. Is Big John talking to you yet? Ever find out what his gripe was?
I'm not bad, Martin. No, haven't heard from John. Managed to make 29 peaks in the end - was good to meet up with you in Austria.
Are you going to be in England in the summer? If so, give me a shout!
Running my camp at Wycombe Aug 23-27, and then over again at ski show time in October. Well done on the White Peaks - I notice the SCOPE Colorado event unfortunately clashes with the Epic Ski Academy, which I notice you are a big fan of...
Martin Bell wrote "Even as late as 1997, there were shaped skis that would carve easily, and fat skis that would float easily, but no shaped fat skis, so it wasn't particularly easy to carve through powder."

Are you saying here that without a sidecut a ski won't carve or is just more difficult to carve?

I've not used such fat skis but I had always assumed that they would deflect beneath your weight and allow you to make carved turns, in the same way that better skiers on old 'straight'er skis were able to despite lack of sidecut.

I suppose my definition of a carved turn would be one in which the ski is deflected (bent) and travels along the arc that that deflection descibes with the tail following the tip.

Something discussed elsewhere (thread about PMTS) is just how the shape changes as turn radius varies, does the tip somehow set a new course or does the foot bend the ski from the midpoint into a new shape. Well we have all summer to sort that one out.
Quote:
 Originally Posted by daslider Are you saying here that without a sidecut a ski won't carve or is just more difficult to carve?
Just more difficult. There already exists an example of a ski (sort of!) that has no sidecut but can carve - it's called a grass-ski. Although the rail that carries the belt is bent into a permanent "reverse camber" shape (saving the skier the effort of having to bend the ski for each turn), the "plates" that are in contact with the grass are all of the same width, so the sidecut is 100% straight. Yet, if you watch grass-skiers, or try it yourself (Arthur's Seat would be ideal) it is clear that the movements and sensations are similar to those of carving. And unless it's particularly muddy and the dreaded drift kicks in, the "hard snow" definition of carving ("all points on your edge will pass over the same point in the (packed) snow") does hold true - replacing "snow" with "grass" of course.
Thanks Martin Bell, the grass ski does rather bare out the conclusion that it is not the sidecut but the effective reverse camber that allows carving, and therefore that carving can happen with turkey and with whipped cream. As the Arthur's Seat snowmaking scheme seems to be on hold, grass skis maybe the answer and we've certainly had some fun there on a mountain board. Have you ever done Edinburgh's 5(?) Peaks? (Corstorphine, Arthur's Seat, Braids, Castle Mount, Calton Hill).
No, but at Hillend I have skied on 3 surfaces: plastic, grass, and snow (on the golf course - the golf club was not impressed).
By the way, when I was a kid growing up in Edinburgh, my mum always said that the city was "built on seven hills, just like Rome" - maybe your five, plus Blackford Hill and Craiglockhart Hill?
Quite right, I had forgotten those 2, though for some reason Craigmillar is sometimes included rather than the higher Craiglockart. The account I've heard, which really ought to be published, involved doing the whole circuit early in the morning before the Parks police could intervene and/or the snow melted which included the steep south face of the Seat (because the Parks police had anticipated the easier route), and then the narrow Clermiston Road down from Corstorphine amid the floundering traffic!
If you want to see a good example of soft snow carving, or rather heli-skiing where the skiers are actually making short to medium radius slalom turns in bottomless powder check out the most recent Warren Miller film. There is a section in it that was filmed by and for Salomon (to be used in their 2003 - 2004 promo DVD) that shows ex racers (now free skiers) making some quite astonishing turns in powder - leaving perfect trenches and springing back and forth as if they were on a shorty slalom ski. These turns were made on short AK's, short Xtra Hots, and Pocket Rockets (mostly Pocket Rockets) - all team issue of course due to the level of the athletes. The Salomon DVD is the best place to find the clips but it is hard to come by. It really shows what a short fat soft powder ski can really do.
Later
GREG
Quote:
 Originally Posted by daslider Thanks Martin Bell, the grass ski does rather bare out the conclusion that it is not the sidecut but the effective reverse camber that allows carving, and therefore that carving can happen with turkey and with whipped cream.
Yes, but to avoid confusing anyone, you should add that greater sidecut does enable the easier achievement of reverse camber - I'm sure you meant to add that anyway!
Quote:
 Originally Posted by Martin Bell The notion that carving can occur in deep powder is also of fairly recent vintage. Ski films were pretty much full of skiers using bouncy short turns in the deep stuff until Nobis started carving big SG turns down Alaskan faces. Fat skis weren't essential but they gave him and the likes of McConkey the confidence to ski that way. Of course, the sideways standing fraternity were ahead of the 2-plankers when it came to arcing long turns in powder...
Well I guess I'm not the only one who thinks it's O.K. to carve SG turns in moderately (real steep won't hold deep) steep and deep snow. I did it on SG skis back in the late 1980s though; I bet it's a little easier with softer tails.
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