critiqued by a ski instructor...wigglers unite!

[sledhaulingmedic]

Let's separate the instructors from the method. I'm not picking on PSIA instructors, but rather on the PSIA doctine of howskiing is meant to be taught. (A s an analogy, I hold a National Ski Patrol Outdoor Emergency Care Certification, (along with National Registry of EMT's Paramedic, State of MA Paramedic, TEMS Swat Medic and Wilderness EMT.) While I hold the OEC certification, it's certainly not the only game and I don't believe it's the best.

Likewise, I don't feel that because an instructor is PSIA level whatever, that they are necessarily no good. I've had some great lessons from members of the "E" team. And I've also skied with some with "lesser" certified PSIA types who were outstanding. What I have found is that the "PSIA Method" seems to focus too much on carving on groomers and very little else. Don't confuse that with the ability of some (and probably many) PSIA instructors to address other issues, but from my very limited experience, when they do that, it's outside of the PSIA doctine.

 

[Marc]

I frickin hate the National Registry. They're such pains in the ass. I let my NREMT-B go. w00t CT DPH.



Sorry, I'm still a little bitter.

 

[KevinF]

What I have found is that the "PSIA Method" seems to focus too much on carving on groomers and very little else. Don't confuse that with the ability of some (and probably many) PSIA instructors to address other issues, but from my very limited experience, when they do that, it's outside of the PSIA doctine.

I am not sure what this "PSIA doctrine" thing is suppossed to be. I have had the good fortune to be coached by some of the more senior members of the PSIA hierarchy over the years.

First, let me agree, that there are a good number of instructors out there who are bad teachers and not the greatest skiers themselves either. In any large organization, there will be bad apples. There are bad doctors, bad lawyers, bad engineers, and bad teachers of every discipline.

The PSIA doctrine, as I have been taught it, is simple: there are three things you can do to a ski. rotate it, edge it, and pressure it. If you prefer to think of it in aeronautical terms, you have yaw, roll and lift.

How you choose to blend those three factors is everything. You can get everything from a pure carved turn to the windshield-wiper 100% skid. Master all three components and learn to blend them seamlessly and you have some incredible skiing to watch. The trick is finding an instructor who can actually utilize all three and, better yet, teach you how to do the same.

 

[gladerider]

which way do you like better?
i change my stance on the fly based on terrain. i am with the school of thought that a good skier should be able to ski any type of terrain. very tough to ski wide stance through deep moguls...or in bumped up tight glades....

 

[sledhaulingmedic]

I frickin hate the National Registry. They're such pains in the ass. I let my NREMT-B go. w00t CT DPH.



Sorry, I'm still a little bitter.

I keep mine for the cool looking patch

Back to our regularly scheduled thread, already in progress.

My experience (however limited) with instructors teaching by the book, PSIA-wise, is that the PSIA aproach is to teach carving on groomers. This view has been supported by conversations with several NSP ski examiners, including certified.

Now I know that the PSIA and NSP are dangerously incestuous, but I still hold the PSIA in higher esteem than the upper ranks of NSP (whom I rank somewhere below blood sucking leeches:smile

 

[OppositeGeorge]

Yeah, you're going in the right direction, but your physics seem a little iffy. I would imagine that the coefficient of friction has less to do with stance width than does the centrifugal/centripetal forces that you would have to manage (where a wide stance would be more beneficial for stability at speed). But, like you, I'm no physics expert.

I know just enough physics to get me in trouble but why let that stop me from throwing in my undereducated two cents?

The way I see it there are two coefficients of friction we're interested in -- the one we normally think of operating lengthwise and the less-obvious coefficient of friction operating perpendicular ("normal") to the length of the ski; that is, how much centripetal force the hill/edge interface is able to supply to keep your skis from sliding out from under your feet. Even though we don't usually think about it as a coefficient of friction, probably because its value is much, much greater than the COF parallel to the edge, that's exactly what it is.

We all control this "normal COF" by adjusting our edges, and varying stance allows us to fine tune how the centripetal force gets apportioned between the skis. Specifically, a longer baseline between the centers of the feet (wider stance) allows for a more subtle variation in force apportionment between the skis for a given center of mass/line of action shift. And thus we control individual edge force better with a wider stance and so help fight washout. So, so far I'm in agreement. But ankle roll/edge angle control (which, remember, is our major input controlling the normal COF) is to a large part also dependent on this force apportionment, and I think that the additional control over force apportionment that a wider stance offers would therefore allow for better fine tuning/maximization of normal COF on each ski.

We need a lower normal COF when we're sliding on a more-compliant, less-elastic surface (i.e., softer snow,) and because the COF peaks somewhere in between the extrema of edge angle (roll too much or too little and your edges wash out) softer snow means we can be sloppier and still carve turns. This means we can get away with a narrower stance on softer snow and less-steep slopes, and enjoy the other advantages of skiing with feet close together (e.g., smaller center-of-mass displacements required for balance reapportionment.) OTOH, the relationship of COF to speed is more complicated as increasing speed, and therefore radial acceleration for a given turn radius, increases the downward force at the snow/ski interface and the force required to resist washout is the product of downward force and COF. It turns out that a wider stance offers at least as much if not more stability at higher speeds, but I'm not sure if the model developed above is sufficient to explain why.

(I think.)

 

[OppositeGeorge]

I maintain that anybody who can lay way over into a carved turn has (or at least could very easily) pick the inside ski right up off the ground anytime they felt like it. Saying your inside ski is "holding your weight" is, IMHO, wrong. The only time my weight falls onto my inside ski is when I've just made some really big mistake.

Up until last week I would have agreed with you. Since then I've taken some classes emphasizing the importance of independent balance and pressure control and have found much better results when I ski on both skis as opposed to just the outside one, even on (especially on?) steeper, icy runs.

Getting to this point was a bit scary, but we had a good instructor who drilled the hell out of us and made us ski just on the inside ski for a long time before getting back to outside ski involvement.

 

[riverc0il]

I am with OppositeGeorge on this one. The idea that the outside ski carries all your weight and force and carving is independent of the inside ski is old technique. I have seen various percentages of ideal weight, but suffice to say while the outside edge carries more weight, it is not a completely overwhelming majority. I could no more pick up my inside ski mid-carve than my outside with risking serious off balance issues. Not convinced? What some pro video of racers who routinely loose their outside edge but hold a turn on their inside ski. Pretty wacked out stuff.

 

[OppositeGeorge]

I have seen various percentages of ideal weight

My hunch is this is heavily dependent on conditions, slope and intended maneuver.

 

[drjeff]

The biggest difference you'll often see in the wigglers vs. wide trackers technique debate is in the hips. Most wiggler's (and I'm not talking bumpers in the zipper line, but the "old school" on the groomed knees/ankles welded together wiggler's) will early in their turn rotate their downhill hip out from their body and then their feet somehat follow, but never really get our from under them. Basically causing their upper body to act as a counter weight to their lower body with the fulcrum point being their pelvis.

Most wide trackers willl get their feet way out from under them and maintain a much more straightline posture from their ankle to their head, with no real fulcrum.

Wiggler's (even bumper's in this observation) also tend to maintain a taller stance where as wide trackers tend to have more vertical motion.

Me, I like the wide track, and I know that I'm in a good, stable position if my uphill ankle is further downhill than my downhill knee during my turn. If you can really get the angulation going and the skiis hooked into the snow with a solid carved turn the energy rebound you can get when linking some turns this way as a wide tracker gets real similair to the sensation you get when "floating" through deep powder.

 

[JimG.]

I am with OppositeGeorge on this one. The idea that the outside ski carries all your weight and force and carving is independent of the inside ski is old technique. I have seen various percentages of ideal weight, but suffice to say while the outside edge carries more weight, it is not a completely overwhelming majority. I could no more pick up my inside ski mid-carve than my outside with risking serious off balance issues. Not convinced? What some pro video of racers who routinely loose their outside edge but hold a turn on their inside ski. Pretty wacked out stuff.

I agree.

Especially on steep terrain.

 

[jaywbigred]

I don't know where the "increased surface area" concept is coming from. Two skis have the same amount of area no matter where they're held.

I guess what I should have said here is effective surface area? My physics is weak, but I think that in supporting the same amount of weight, two skis held closer together provide more effective weight distribution and thus float in softer snow. Not sure though.

I maintain that anybody who can lay way over into a carved turn has (or at least could very easily) pick the inside ski right up off the ground anytime they felt like it. Saying your inside ski is "holding your weight" is, IMHO, wrong. The only time my weight falls onto my inside ski is when I've just made some really big mistake.

I am going to hop on board with OppositeGeorge, Rivercoil, and Jim G on this one, and disagree with you. If you are properly angulating, your uphill ski will certainly be providing some degree of weight support. I am not saying it support anywhere near to all, or even most, of your weight, but it certainly should be providing some. I agree with others' advice to look at a modern ski racer in a turn with an angulated uphill ski; then imagine him with one leg only...would he still be upright? I also agree that watching a skilled racer recover a turn in which they have lost the downhill edge by completeing the turn with the uphill edge is a good exercise as well.

...and the less-obvious coefficient of friction operating perpendicular ("normal") to the length of the ski...Even though we don't usually think about it as a coefficient of friction, probably because its value is much, much greater than the COF parallel to the edge, that's exactly what it is. .

Yep, that was the one I was referring to.

We all control this "normal COF" by adjusting our edges, and varying stance allows us to fine tune how the centripetal force gets apportioned between the skis. Specifically, a longer baseline between the centers of the feet (wider stance) allows for a more subtle variation in force apportionment between the skis for a given center of mass/line of action shift....[however] We need a lower normal COF when we're sliding on a more-compliant, less-elastic surface (i.e., softer snow,) and because the COF peaks somewhere in between the extrema of edge angle (roll too much or too little and your edges wash out) softer snow means we can be sloppier and still carve turns. This means we can get away with a narrower stance on softer snow and less-steep slopes, and enjoy the other advantages of skiing with feet close together (e.g., smaller center-of-mass displacements required for balance reapportionment.)

I believe this is the correct way of stating what I was trying too in my much-less-well informed post.

Which lends credence to what drjeff says, which I agree with, that

If you can really get the angulation going and the skiis hooked into the snow with a solid carved turn the energy rebound you can get when linking some turns this way as a wide tracker gets real similair to the sensation you get when "floating" through deep powder.

 

[OppositeGeorge]

I guess what I should have said here is effective surface area? My physics is weak, but I think that in supporting the same amount of weight, two skis held closer together provide more effective weight distribution and thus float in softer snow. Not sure though.

Okay, I'm getting deep into blowing-this-out-my-ass territory here, so indulge me but please feel free to nitpick and correct. This is all really just thinking out loud:

I think in the interest of clarity maybe we should forget about the term "surface area" (temporarily -- see below) and focus on the second half of what you said -- more effective weight distribution. The more I think about this whole subject the more I suspect that the close-together stance is better in powder because those conditions are so, so sensitive to pressure -- put just a tiny, tiny bit too much weight on one ski and that ski goes right down (as I recall... as a NE skier my experience in such conditions is rather limited...) And you have to tweak this all the time in response to microconditions and terrain.

Anyway, getting back to the point, my guess is that because the sinking happens so fast you're better off being able to react quickly and often to keep both skis floating evenly. Remember, close skis mean less center-of-mass movement required to adjust relative pressure means faster reaction is possible. Trying to remember what skiing deep powder is like (again, hazy memory here,) and imagining keeping the legs wide apart, it seems you would get way out of balance really fast. That's because (again, a guess) you need to move so much more to correct pressure, and also once one ski gets really deep the whole geometry of the setup changes and now you have to move in ways you're not used to (as well as fight gravity if it's the downhill ski that is overweighted) in order to get back over the shallower ski. And there's probably a bit of a non-linear, runaway phenomenon too -- the time you have to straighten things out likely gets (exponentially? polynomially?) worse as out-of-balance increases.

Now, back to the surface area thing -- since skis have a low coefficient of friction on the sliding surface and also because soft snow is a deformable surface, surface area perpendicular to the line of action is probably what we're most concerned with. In other words, flat skis float and edged skis dig in. So it isn't inconceivable that altering stance will change the "flatness" (base perpendicularity to line of action) and change that "effective surface area." Obviously, the best stance to keep the skis flat depends on a lot on the individual, but my guess is most of us are built in a way that on most hills the flatness sweet spot maxes out someplace where the feet are relatively close together.

In other words, even though base surface area doesn't change regardless of stance, a stance leading to flatter skis yields more "effective surface area" than the alternative. It would seem that would only help in powder (but it's just one component in a complicated equation.)

Anyway, all the above is hypothesis and it wouldn't surprise me if there's something very wrong about the line of reasoning. Be interested in hearing everybody's thoughts.

 

[OppositeGeorge]

Or maybe a different way of stating the first part of the previous tome. I think the physics is the same but this is simpler: Think about pulling up on the sinking ski. It's easier to do this when your leg is relatively straight than when your knees and ankles are way out and you have to do it through an angle (try it.) Close-together feet means straighter legs means an easier time of it. (Maybe?)

 

[jaywbigred]

Both good points. I agree especially with your points regarding reaction time to correct a mistake being less in powder. Two the degree that, in carving, a skier coordinates each leg differently, in powder, the reaction time decreases to a point where the independent leg coordination becomes inordinantly difficult. The answer is to move the feet closer together so that the skis work less independently and can be coordinated as more of a single unit.

Also, we can't forget that deeper snow also adds friction (drag?) around the feet and legs (and maybe more, if you are really lucky!). In a wide stance, varying snow properties (depth, weight, compacted-ness, etc) would effect each ski, foot and leg differently, further hindering the ability of the skier to coordinate each ski as a seperate entity.

 

[OppositeGeorge]

Also, we can't forget that deeper snow also adds friction (drag?) around the feet and legs (and maybe more, if you are really lucky!).

In a wide stance, varying snow properties (depth, weight, compacted-ness, etc) would effect each ski, foot and leg differently, further hindering the ability of the skier to coordinate each ski as a seperate entity.

Agreed. I was dancing around this with the term "microconditions" but didn't get all the way there. You stated it it much more clearly and flipped a switch here in my gourd -- thanks!

 

[JimG.]

I smell smoke.

Skiing lends itself to the on snow demo.

Talking about it gets convoluted to say the least.

I agree with the comment that a narrower stance is more efficient and effective in deep snow.

 

[ckofer]

τ=r X F
F=m * a
e=m * c^2

In other words if you're taking a fast turn on your inside ski, you're close to failure. If you keep your skis together, they are easier to control as if one big ski but harder to carve with. This is more about you than physics. The third equation? Ask Einstein. I googled Einstein and ski. The most promising looking link ended up passing me over to a p0rn site which tried hard to load and .exe file onto my Mac. I guess he didn't ski much but he probably would have tele'd.

 

[OppositeGeorge]

Einstein was kind of known for baggy pants so obviously he would've been a snowboarder.

 

[jaywbigred]

Einstein was kind of known for baggy pants so obviously he would've been a snowboarder.

I dunno. With the 'stach and hair he sported, he reminds me more of those grizzly old telemarkers I so envy...