 Poster: A snowHead
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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Dan, Yeah? and that retching noise behind the lift cabin is not breakfast saying hi again?
Got to be honest here, my usual experience of 'Spawn of Masque' and his mates on an early lift is . . . stumble, whinge, sleep on the way up, sit down at the top and roll a phat-one to share! I pick up the idle ßuggers on the second uplift and warch half a dozen semi-concious clowns eat snow for the first half hour. They do, eventually, improve . . . coffee helps. 
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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You need to Login to know who's really who.
You need to Login to know who's really who.
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Physicsman-you're not Tom Jungst, are you?
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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Physicsman, I agree that fats are a great help off piste and can make a huge difference to the clients' enjoyment of it, but at the end of the day there's no substitute for good technique. If you have bad technique you fall over in deep snow - end of story. If your technique is reasonable you can cope with it.
Having said that the newer slalom skis are virtually unskiable in deep snow. Personally I only have 2 pairs of skis and no locker room (here in France we go up the mountain in the morning and carry on teaching until the end of the day) so I have Volkl P50's (slalom) for everyday use and Rossi Scratch FS (yes FS) for days when I expect to go off piste. I find them great, they carve adequately, plough well and float off piste being so soft. Oh yes, they also weigh about half as much as the Volkls.
I use deep snow as a sh*t or bust teaching technique. 
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You'll need to Register first of course.
You'll need to Register first of course.
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kevin mcclean: Physicsman-you're not Tom Jungst, are you?
Given his extreme skiing reputation, unfortunately, not.
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easiski: Having said that, the newer slalom skis are virtually unskiable in deep snow.
Amen, brother! That's exactly my experience as well. I would rather be on my 1980-era 205 Volkl Zebra than on some of these skis. With respect to new designs, it will be interesting to see how the new Atomic Metron B5 works out. It has a SL-like sidecut (11 m), but is something like 76 mm underfoot, so Atomic is claiming that it will be the best of both worlds. I'm worried that it will be the worst.
The recreational slaloms make darting around the groomers so much fun that I see ever increasing numbers of guests on them. Unfortunately, when it begins to snow, these people then find themselves on a really inappropriate and difficult to handle equipment.
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easiski: I use deep snow as a sh*t or bust teaching technique.
I don't know why, but for some strange reason, my ski school director just isn't big into that technique. 
Tom / PM
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I agree 100% with Physicsman. I tried out some fats in very heavy spring powder/sludge last season. Rarely had such fun. You should bear in mind that having fun is what it's all about. Nobody is going to be impressed by the fact that you can do powder on skinny skis. They'll just ask themselves why you look as though you're working too hard. If you look at what the good powder skiers are using these days, it's always something fat.
In fact I found that the fat skis were quite useable on the piste as well. Obviously not the same as race carvers, but you get around.
Right now I still ski fairly long (1.90) Atomic 11.20s, which are billed as powder skis, but the next pair that comes into my cellar will definitely be shorter and a lot fatter!
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Mike offered what I consider to be an excellent perspective on fats from the point of view of a recreational skier.
His comment, "... In fact I found that the fat skis were quite useable on the piste as well. Obviously not the same as race carvers, but you get around. ...", is what I and many avid skiers in our Pacific NW region feel. I have often said that I would much rather unexpectedly encounter ice on a pair of fats (caveat - of reasonable stiffness, with well maintained edges) than unexpectedly encounter deeply rotted, tracked up slop on narrow or even mid-fat skis.
I presently own three pairs of fats (95, 95, and 114 mm wide underfoot), and have intentionally taken each of them out on icy days to test the limits of their performance before I came to the above conclusion. I have also skied soft, difficult snow for 20+ years on skinny straight skis, and the last ten years on "shaped" skis in difficult soft snow before I bought my first pair of fats about 7 years ago, so, I certainly know that can be done as well. My conclusion is that I'd much rather be in the first situation.
Tom / PM
PS - I should also add that for a 110 lb woman a 65 mm wide ski will likely float higher and be able to turn more easily in soft snow than a 220 lb guy would get on 95 mm skis, so, what's "fat" for one person may or may not be fat for another. IMHO, I consider "fat" as a performance description, not an actual width in mm. I have written quite a bit about this over on Epic, and if anyone is interested, I can post some links to those threads.
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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| Quote: |
if anyone is interested, I can post some links to those threads.
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Physicsman, Please do. I am interested and I'm sure others will be too.
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Maggi – In looking over the threads on this subject over on Epic, my current feeling is that the basics get a bit lost in the lengthy discussions, so I’m going to try to summarize things first, then provide the links.
The basic idea, stripped of all the details, is that the physical quantity that is most important in determining how far snow will indent when weighted is the pressure (ie, pounds per square inch, or per square cm, or whatever) that is being applied to it. As an example, if a 100 lb woman is on a very stiff ski which has a load bearing area of 1000 square cm, she will be applying 0.1 lbs per sq. cm. to the snow, and that will indent the snow by a certain amount, say 1 inch. If a 200 lb guy is on the same snow on a very stiff ski which has a load bearing area of 2000 square cm, he will also be applying 0.1 lbs per sq. cm. to the snow, and to a very good approximation, he will also indent the snow by 1 inch.
If skis were infinitely stiff, had no sidecut, and were simple rectangles, the load bearing area would simply be the length times the width. They do have a non-rectangular shape, so one has to use the average width. As one goes towards fat skis, their waist widths increase, but so do the tip and tail dimensions, so, to a reasonable approximation, a 10% increase in waist width will increase the average width by a number pretty close to 10%.
Thus, if you keep the length of the skis under consideration constant, one can set up a simple proportionality between waist width and skier weight that will keep the pressure on the snow (lbs per sq. in.) constant. This is the basis of my “equivalent float chart”. For example, here are one set of numbers, originally posted on http://forums.epicski.com/showthread.php?t=521 that holds the pressure (ie, float) constant at one value:
(lbs)..(mm)
100.....49
120.....58
140.....68
160.....78
180.....87
200.....97
220....107
240....117
260....126
Thus, if you are a little slip of a 120 lb woman, you will have the exact same float on a 58 mm wide pair of skinny boards that Mr. Average Guy (at 175 lbs.) has on his 85 mm "lite-fat" skis (eg, Rex, g4s, etc.)
Basically, on any sub-70 mm ski currently being sold (because they are all greater than 60 mm), Ms. 120 Pounder will sink in less than Mr. Average Guy on his Rex's, so its to be expected that a light weight person might not fully appreciate the need for fatties (at least from direct personal experience). At the other end of the spectrum, at 210 lbs, I will need to be on 100 - 105 mm boards to achieve the same float as Mr. Average Guy on his sticks. The bottom line is that guys, especially big guys, have a valid point in wanting to be on wide skis in soft snow.
Next, I have to throw in a few “ifs, ands, and buts”, mostly related to the fact that skis are not infinitely stiff in flex.
1) Their waist area deflects into soft snow more than their tips and tails. This raises two issues. The first is what is the exact definition of “float”. Do you consider “float” to be how far the skier (ie, his boots = the middle section of the ski) sinks in, or do you consider “float” to be the average depth of compaction of the snow over the length of the ski? I consider it to be the former, so, without going through the formal argument, this emphasizes the actions of the center of the ski more heavily and makes the linear scaling approximation I presented above even more accurate.
The second issue that ski flex introduces is that flex concentrates the pressure that the skier is exerting on the snow in the middle section of the ski. Again, without presenting a formal argument, I will again simply state that this also makes the linear scaling approximation mentioned above even more accurate.
2) I should caution that the above chart says absolutely nothing about how the indentation depth (float) varies with changing pressure, only that at the same pressure, the indentation will be the same. So, for example, If the guy in my first example is now on 1000 sq. cm. skis instead of 2000 sq. cm skis, the pressure he will be applying to the snow will now go up to 0.2 lbs per sq. cm. This does not mean that he will indent the snow by 2 inches. The indentation may be more (say, if the snow is rotten underneath), or less than 2 inches (say, if the snow is of a type which compacts into a firm mass under pressure and doesn’t crumble).
3) I should also caution that this chart doesn’t explicitly say anything about how easily a fat (or other) ski will turn in soft snow. Softer skis will carve turns in soft snow more easily, but be more easily deflected by crud. For a given weight skier, a softer ski will also flex in the middle more than a firm ski, putting the skier deeper into the snow and making it seem like it has less “float” (at least in one sense). OTOH, there will be more upward curvature to the forebody of the ski, and this will tend to prevent dreaded “tip-dive” and going over the handlebars.
4) Finally, I should point out that adding width comes at a cost. For example, both the overall mass of the ski and the swing weight increases dramatically as you “go fat”. This makes both pivoting moves as well as retraction/extension moves (ie, porpoising ) require more energy and become slower. Also, when used on hardpack, wide skis require more torque from angulation to keep them at the same edge angle.
Here are a few threads over on Epic which discuss these and related issues:
http://forums.epicski.com/showthread.php?t=1441&page=3 (I joined the thread on page three)
http://forums.epicski.com/showthread.php?t=650
http://forums.epicski.com/showthread.php?t=12250 (discussion of skis for spring slush)
HTH,
Tom / PM
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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Thanks Tom. Absolutely fascinating! And at 116 lbs, I guess you've saved me some money - I don't need fat skis!
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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comprex,
As opposed to the 2 dimentional stuff 
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You know it makes sense.
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Maggi I think that by 3d comprex meant that in powder/crud a skier is in the snow (much like a waterskier really) rather than on the snow...
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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| maggi wrote: |
| Thanks Tom. Absolutely fascinating! And at 116 lbs, I guess you've saved me some money - I don't need fat skis! |
You are quite welcome.
BTW, don't forget that while my little table may tell you that you get the same float on (approx) 58 mm skis that a 180 lb-er would get on 87 mm skis, you may actually prefer even more float than that.
As an example, during a 30 inch dump we were getting, my daughter (~ 75 lbs at the time) pleaded with me to let her try the short pair (165 cm) of Explosivs (95 mm waist) that I own. I told her that these were heavy, stiff skis that were typically used by full grown adults, including some of the best powder skiers in the world. She persisted, so I reset the bindings and off we went.
After about two turns, she had them dialed in, and was skiing beautifully - absolutely flying, when almost everybody else on the mountain was bogged down, fighting the heavy wet snow. When you looked carefully, you could see why. She was so light for that width of ski that she hardly indented the snow at all, so she was able to ski it exactly like one might ski freshly groomed corduroy, and could even do skidded turns (which were absolutely impossible for anyone heavier and/or on narrower sticks).
After a couple of hours on them, their weight started to get to her and she decided to go back to a pair of 75 mm wide sticks. These didn't float quite as high as the Explosivs, but they floated adequately AND were much more maneuverable and obviously took less muscular effort to ski.
I would interpret the table this way: For someone of your weight, the (float) performance of skis will change dramatically in the range 55-70 mm wide, whereas for someone of my weight, the (float) performance will be essentially constant up to about 85 or 90 mm (ie, they will hardly float unless going at high speed - another issue, not yet mentioned in this thread), and for me, the transition to true "fat ski" behavior will come in the range 90 - 110 mm wide.
So, as in all ski purchasing decisions, aids like my "equivalent float table" can help guide the decision, but deciding on exactly what is optimal for you is best done by demoing.
HTH,
Tom / PM
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FAQ
