Buying AT skis?

[beecher]

not sure what you're trying to say Hugh

 

[Hugh Conway]

not sure what you're trying to say Hugh

 

area of the ski is what matters - people use base width underfoot as a proxy for ski area. if it was only the area "underfoot" that matter snowlerblades wouldn't be the ski equivalent of a $10 backalley blowjob

 

All sidecut is not the same - where matters as well as how much, so do tip profile, yadda, yadda yadda. Same with flex - theres more than stiff or floppy,

[hafilax]

Water and air analogies don't work well because snow isn't a fluid.

Halifax, I've gotta disagree with your statement, and I think you might too (hence the surfboard reference). Snow is not air or liquid water. But water is not air either (air being compressible, water not so much), and yet somehow the physics of a rudder, keel, or propeller blade in water are very similar to the physics of a rudder, wing, or propeller blade in the air. I am not saying there's no difference.

 

Is it just coincidence that the community agrees that the area underfoot is what counts?

 

Area underfoot = Boot length x Ski width.

 

My boot length is the same no matter what ski I'm on, so the agreement is really that the width of the ski is most important. Same conclusion the basic physical models based on fluid (or aero) dynamics would come to.

 

We all get the same fun results no matter how (or whether) we think about it.. yeeha!

You keep referring to Bernouli principal in fluids which does apply to both water and air but not to snow. The ski deflects the snow but there is no restoring force. I don't think snow behaves as a fluid. It's more like a foam. It doesn't break under small forces so it can creep, stretch and compress slightly but it crushes under larger forces without restoring much.

 

The area under foot is a rule of thumb for judging the relative area of skis of the same length. My girlfriend and I have skis of similar length and max width but mine have much less sidecut. Mine therefore have much more area for the length and float way better. Wider skis generally have less sidecut because area is important in powder and sidecut isn't so the width under foot is a better indicator of the total area than the max width. I also speculate that area further from the feet isn't as useful in providing float as the area under foot because of the flex of the ski.

 

I think the reason that people have been trending toward short fat skis in the backcountry is that they are more manageable for short quick turns in varying conditions. The width gives the float in the powder and since the moment of inertia goes like m*r^2 it quickly gets harder to turn a longer ski. Especially if you start piling heavy snow on the tip and tail. Kick turns are way easier with a short ski. The trade off is less stability at high speed and in tricky edging conditions. A long fat ski is just plain heavy.

 

The biggest problem with snowblades (which are an embarrassment) is that it is easy to get your center of mass past the tip/tail. This is completely unstable which is why snobladers do more running than skiing in deep snow. A taller person needs a longer ski regardless of weight.

 

There are other trade offs as well. A stiff heavy ski with heavy boots and bindings will be more stable at speed because of the increased momentum. Less of the forces from choppy snow are felt my your legs. A lighter setup will bounce you around.

 

So it's an optimization problem with compromises. There is no best setup for all applications otherwise there would be only one ski company. The best advice will come from someone of a similar size, ability and who skis in similar conditions but even then tastes vary. Demo's are your friend.

[beecher]

when comparing flotation of skis, and not snowblades or blowjobs, I have to stick with width underfoot being the most important criteria.

 

you're gonna pick a pair of POWDER skis that's about as fat as you'd like them to be, and a length suitable to how you want to ski that particular ski. You're not going to pick a ski of a given width and say "OK, what length will give me enough area in order to stay on top of the fat pow".

 

174cm Bandit B100 vs. 185cm Bandit B94

B100 has 100mm underfoot, B94=94mm

Which stays on top best after 12" fresh?

 

[beecher]

novascotian,

i agree with 90% of what you're saying. the selection of skis has almost nothing to do with the physics of how they generate lift, there are other more important factors.

 

all i'm saying is that powder snow flows over the bottom of skis and generates lift. and skis act a lot like a wing, or a boat, or a pair of, well, skis on the water. you change the angle of attack of a ski, you get more lift. you go faster, you get more lift. you ski through snow and it sprays off the sides of the skis from the pressure under there.

 

i'm not saying if the duck floats you're a witch.

[Hugh Conway]

174cm Bandit B100 vs. 185cm Bandit B94

B100 has 100mm underfoot, B94=94mm

Which stays on top best after 12" fresh?

 

Don't fucking ask me I'd never ski shit that short

[hafilax]

I agree that there is a dynamic force that depends on the velocity of the ski over the snow. What I'm saying is that there is a transfer of momentum from displacing the snow not a force due to differential velocities over opposite sides of a surface like with a wing. This is an effect similar to a boat planing which you have describes although the actual equations describing it would be much different since snow is not a fluid.

[Hugh Conway]

I agree that there is a dynamic force that depends on the velocity of the ski over the snow. What I'm saying is that there is a transfer of momentum from displacing the snow not a force due to differential velocities over opposite sides of a surface like with a wing. This is an effect similar to a boat planing which you have describes although the actual equations describing it would be much different since snow is not a fluid.

 

Alot would depends on the density of the snow. I've skiied some powder where it was hard to see the tracks left and it did almost flow. True "blower" pow. It would model much like a fluid.

 

Sasquatch will be seen in WA before that stuff

[beecher]

Don't fucking ask me I'd never ski shit that short

i thought i'd keep the numbers small so you'd be able to do the math.

looking forward to seeing you double eject while you show the ladies how fast you can go. ohhh wait, i bet your din's at 14, isn't it, you big mountain skier you. everyone knows all the best skiers are on the internet right now.

[beecher]

forget about equations and the semantics of whether snow is a fluid or not. give me one more chance, i promise, no fancy words like stagnation or any bullshit like that:

 

the little flakes. the ones under the ski there. they are applying a pressure to the ski as it moves along. the snow flakes or bits (like the ones bacon are made out of) are individual lil' pieces that can stick together to form larger bits, separate from each other, or change state under pressure (who cares).

 

These 'lil bits will seek an area of lower pressure, someplace it's real easy to go. if they are near the edge of the ski, they will run like hell, and if luck has it hit you in the face. The longer the 'wetted' (call it 'snoweded' if that helps) edge of the ski there is relative to the total wetted area, the more little bits will be able to run away instead of helping lift your smiling self above the masses of little freedom-seeking snowbits.

 

somewhere under the front end of your ski there will be little snowbits trying to escape, but that are too close to the middle to find the side of the ski, and my where will they go? they will rally a group of resistance fighters there for a fight to the death. a lucky few may be spat out the front, the rest are smashed underfoot. little do they know, but they have only aided your cause, raising pressure in their little cell of resistance.

 

As you go faster and faster, the pressure you're feeling down there on your skis will become greater and greater and oh my you'll soar higher and higher until fewer and fewer snowbits will be needed for you to sail proudly past the admiring onlookers. You become a stormcloud of snobits scattering fanatically spraying madly and dissolving into the mouth of a madman..

 

least that's how i think of it

 

[Hugh Conway]

looking forward to seeing you double eject while you show the ladies how fast you can go.

 

only women can multiple orgasm

 

for 12" of fresh stayin on top isn't a big concern.

[hafilax]

Beecher, sounds like you're talking about Maxwell's demons.

[beecher]

only women can multiple orgasm

for 12" of fresh stayin on top isn't a big concern.

fresh snow, not meat

 

Beecher, sounds like you're talking about Maxwell's demons.

yep, way too much caffeine today. thanks for the discussion gents, off to google maxwell's demons.