Anatomy of a Ski ?

[aswinter05]

Noob question here. What are all the parts of a Ski? I know what bindings, wings, and fins are, duh. But sometimes I see you guys posting about rocker things, rails, 5 stage this, 3 stage that, blah, blah.

 

I want in. Can someone provide some definitions of all the common waterski parts?

 

( @Horton , I realize this post forever bans me from entering the "Advanced Topics" section)

[ForrestGump]

Rocker is the amount of curve built into the running surface of the ski. It can be a continuous radius curve like a reflex warp or A3, although most skis have rocker in stages. Some skis will have one amount of rocker in the tail, another under the rear foot, another under the front foot, and one in the forebody.

 

Rails are the flat spots in between the sidewall and the concave on the bottom of the ski. Rails can be different widths dependent on the overall width of the ski and width of the concave.

 

Bevels are the radiuses that join the sidewall and the bottom of the ski. They can be round or they can be composed of a series of flats that make up a radius. You can have different bevels in different areas of the ski, too.

 

Sidecut is the amount that the ski profile, when looked at from above, hourglasses or curves inward. You can have a forebody sidecut and a tail sidecut on some skis.

 

Flex is the stiffness of the ski measured at 17", 25", 33", and 41" from the tail.

[ForrestGump]

Rocker is the amount of curve built into the running surface of the ski. It can be a continuous radius curve like a reflex warp or A3, although most skis have rocker in stages. Some skis will have one amount of rocker in the tail, another under the rear foot, another under the front foot, and one in the forebody.

 

Rails are the flat spots in between the sidewall and the concave on the bottom of the ski. Rails can be different widths dependent on the overall width of the ski and width of the concave.

 

Bevels are the radiuses that join the sidewall and the bottom of the ski. They can be round or they can be composed of a series of flats that make up a radius. You can have different bevels in different areas of the ski, too.

 

Sidecut is the amount that the ski profile, when looked at from above, hourglasses or curves inward. You can have a forebody sidecut and a tail sidecut on some skis.

 

Flex is the stiffness of the ski measured at 17", 25", 33", and 41" from the tail.

[Horton]

Ok @Shaneh can you explain "inside radius sidecut?"

[Horton]

Ok @Shaneh can you explain "inside radius sidecut?"

[BraceMaker]

It can be pretty interesting to flip skis over and look down them on a slight angle in different lighting.

 

Add to:

Full Concaves

Tunnel Concaves

 

 

[BraceMaker]

It can be pretty interesting to flip skis over and look down them on a slight angle in different lighting.

 

Add to:

Full Concaves

Tunnel Concaves

 

 

[RichardDoane]

@shaneh - flex is a measurement of the amount of weight (pounds of pressure) that needs to be applied to the ski in those areas in order to flex it 1"

[RichardDoane]

@shaneh - flex is a measurement of the amount of weight (pounds of pressure) that needs to be applied to the ski in those areas in order to flex it 1"

[ForrestGump]

@richarddoane Yes, which is what we all interpret to be the stiffness of the ski in those areas.

 

 

[ForrestGump]

@richarddoane Yes, which is what we all interpret to be the stiffness of the ski in those areas.

 

 

[h2odawg79]

A Ski is also broken down into 3 basic Zones; Zone 1 (from Tail to heel of rear foot) Zone 2 (from rear heel to Front foot toes) Zone 3 (from front foot toes to end of running surface) Each zone will usually have a different (Modified) Bevel.

 

Basic Bevels cuts can range from a hard cut 45 deg to a more rounded (radiused) bevel with little to no 45 deg left in the bevel.

 

(Very Short example) A hard angle Bevel (45 deg w/no radius) will produce an edge that will allow the Ski to sit higher in the water and track like it is on rails. A modified bevel will allow the Ski to roll onto it's edge easier and ride a little deeper in the water, creating a Ski that will turn easier but not track as well.

 

The outside edge of the Bevel (top side of bevel) can be Tuned for particular performance characteristics. As well as the inside edge (bottom) of the Bevel. Tuning would be "Softening" or "Sharpening" the Outside/inside edges, based on the desired change needed.

 

All three Zones will usually have a mixture of edges. "Blending" Hard edges to Rounded edges to create the desired performance Characteristics of the Manufacturer or Personalized by the Skier...

 

Much like Tuning a Fin, tuning the Bevels can enhance or reduce certain performance characteristics of a Ski or help to personalize it for an individual...

 

Caution: Don't break out the File and Block sander and start "Tuning" just yet! -This is waaaaaay more crucial and exacting then tuning a Fin and there is No going back once you've gone a little Too far!

 

 

 

 

[h2odawg79]

A Ski is also broken down into 3 basic Zones; Zone 1 (from Tail to heel of rear foot) Zone 2 (from rear heel to Front foot toes) Zone 3 (from front foot toes to end of running surface) Each zone will usually have a different (Modified) Bevel.

 

Basic Bevels cuts can range from a hard cut 45 deg to a more rounded (radiused) bevel with little to no 45 deg left in the bevel.

 

(Very Short example) A hard angle Bevel (45 deg w/no radius) will produce an edge that will allow the Ski to sit higher in the water and track like it is on rails. A modified bevel will allow the Ski to roll onto it's edge easier and ride a little deeper in the water, creating a Ski that will turn easier but not track as well.

 

The outside edge of the Bevel (top side of bevel) can be Tuned for particular performance characteristics. As well as the inside edge (bottom) of the Bevel. Tuning would be "Softening" or "Sharpening" the Outside/inside edges, based on the desired change needed.

 

All three Zones will usually have a mixture of edges. "Blending" Hard edges to Rounded edges to create the desired performance Characteristics of the Manufacturer or Personalized by the Skier...

 

Much like Tuning a Fin, tuning the Bevels can enhance or reduce certain performance characteristics of a Ski or help to personalize it for an individual...

 

Caution: Don't break out the File and Block sander and start "Tuning" just yet! -This is waaaaaay more crucial and exacting then tuning a Fin and there is No going back once you've gone a little Too far!

 

 

 

 

[MattP]

@richarddoane is it not the amount of pounds to flex the ski .1" ?

[MattP]

@richarddoane is it not the amount of pounds to flex the ski .1" ?

[aswinter05]

Good stuff everyone. Thanks and keep it up. Very informative. Starting to wonder if I'm more confused now or before..

[aswinter05]

Good stuff everyone. Thanks and keep it up. Very informative. Starting to wonder if I'm more confused now or before..

[BraceMaker]

@aswinter05 - one thing that has always intrigued me is the shape of the tail of the ski, and if it is predictive of the ski's feel.

 

For instance the Reflex Hybrid has the swallow tailed area.

 

Nano one has almost a flat back but is radiused onto the tail of the ski.

 

The D3 Quest has almost a round looking tail section.

 

Since we measure from the tail of the ski, I have to assume these differences impact the ski's attitude.

 

But how? Can we predict how a ski finishes a turn? Or perhaps the finish of the turn? Or what does the tail shape do?

 

[BraceMaker]

@aswinter05 - one thing that has always intrigued me is the shape of the tail of the ski, and if it is predictive of the ski's feel.

 

For instance the Reflex Hybrid has the swallow tailed area.

 

Nano one has almost a flat back but is radiused onto the tail of the ski.

 

The D3 Quest has almost a round looking tail section.

 

Since we measure from the tail of the ski, I have to assume these differences impact the ski's attitude.

 

But how? Can we predict how a ski finishes a turn? Or perhaps the finish of the turn? Or what does the tail shape do?

 

[ral]

@aswinter05, I think you got it right on your last sentence.

[ral]

@aswinter05, I think you got it right on your last sentence.

[ral]

@BraceMaker, I think that the Quest statement is a bit extreme...

[ral]

@BraceMaker, I think that the Quest statement is a bit extreme...

[BraceMaker]

What do you call it?

 

http://i49.tinypic.com/11cdqnp.jpg

 

Tail looks round to me.

[BraceMaker]

What do you call it?

 

http://i49.tinypic.com/11cdqnp.jpg

 

Tail looks round to me.

[BraceMaker]

Mapple Tail looks pretty square.

 

http://www.mappleskis.com/images/reel/3/mapple-ski-056.jpg

[BraceMaker]

Mapple Tail looks pretty square.

 

http://www.mappleskis.com/images/reel/3/mapple-ski-056.jpg

[BraceMaker]

So the question becomes, does the shape of the tail of the ski, not the rocker of it, but the shape impact the way the ski feels?

 

@ral - I don't get where I was far off on that being round.

[BraceMaker]

So the question becomes, does the shape of the tail of the ski, not the rocker of it, but the shape impact the way the ski feels?

 

@ral - I don't get where I was far off on that being round.

[MattP]

@bracemaker that first one looks like a red circle, cant see the tail.....

[MattP]

@bracemaker that first one looks like a red circle, cant see the tail.....

[Horton]

Everything impacts how the ski works

[Horton]

Everything impacts how the ski works

[ral]

@BraceMaker, the "section" word made me think about another thing. As in "Section: the profile of something as it would appear if cut through by an intersecting plane ". Yes, all D3's have kind of the same tail shape.

 

I would say that it might have an impact, as @Horton states, but not huge. I can tell you, the tail shape on the Fusion and the Quest are the same or very similar. The rocker of the tail section is different. And the impact of that rocker is significant.

[ral]

@BraceMaker, the "section" word made me think about another thing. As in "Section: the profile of something as it would appear if cut through by an intersecting plane ". Yes, all D3's have kind of the same tail shape.

 

I would say that it might have an impact, as @Horton states, but not huge. I can tell you, the tail shape on the Fusion and the Quest are the same or very similar. The rocker of the tail section is different. And the impact of that rocker is significant.

[BraceMaker]

@MattP - www.d3skis.com - I tried to replicate the shape of the top sheet of the tail as accurately as I could in paint.

 

I'm sure its not perfect.

 

@ral - I'm looking at my skis now, the top sheet on my nomad is round, the bottom of the tail has a flat section in the middle. And I figured you were thinking that, I thought the comparison to the reflex ski which has a V in the rear would make the difference.

 

I guess the basis of it, is how much is this a cosmetic treatment, how much does it just impact how the measurement for DFT is set in relationship to the sides of the ski, and do you think manufacturers try different tails? Rounding them off in body filler, or squaring them up.

 

@eleeski - anything you feel the contour of the tail does specifically?

[BraceMaker]

@MattP - www.d3skis.com - I tried to replicate the shape of the top sheet of the tail as accurately as I could in paint.

 

I'm sure its not perfect.

 

@ral - I'm looking at my skis now, the top sheet on my nomad is round, the bottom of the tail has a flat section in the middle. And I figured you were thinking that, I thought the comparison to the reflex ski which has a V in the rear would make the difference.

 

I guess the basis of it, is how much is this a cosmetic treatment, how much does it just impact how the measurement for DFT is set in relationship to the sides of the ski, and do you think manufacturers try different tails? Rounding them off in body filler, or squaring them up.

 

@eleeski - anything you feel the contour of the tail does specifically?

[h2odawg79]

Since a Ski is designed as a total package, it would stand to reason that 2 identical Ski's would react totally different if the only change between them was a Round and a Square Tail.

 

Example: A rounded tail will generally ride deeper through the Turn and produce a tail that is less prone to blow out, but can create tip rise after apex and a Square tail will ride shallower and help keep the attitude of the Ski flatter increasing the opportunity to hold speed better through the turn.

 

But, these same characteristics could also be replicated or reversed with different rockers, widths, rails and bevels, etc... -that is why everything impacts the ski characteristics

[RichardDoane]

@mattp - I forgot the decimal, you are correct

[Horton]

@h2odawg79 totally different ? No. You are overstating the impact of the tail radius.

[h2odawg79]

@Horton, No. You are overstating the impact of the tail radius.

 

O.K. then, a Significant Difference. (Mainly through the preturn and the Turn aspect) -Enough difference to envoke some skiers to want to adjust their bindings slightlty fwd/aft or tinker with their Fin...

 

can I get an Amen?

 

[Horton]

I asked a pro skier about it today. He gave me a "meh, yea it is a factor"

[h2odawg79]

Can I at least get a "meh," Amen then!

 

of course I was really shooting for a Big Johnny Bravo Hoo Haw Amen... =D

[eleeski]

@BraceMaker and @h20dawg79 I have played a fair amount with the tail shape. Tail shape is a minor factor. Fin adjustments can hide or offset the effects of tail shape on my skis.

 

In theory, sharp edges lift and rounded edges suck. Also sharp edge terminations are lower drag than rounded terminations. In practice these traits tend to offset. The deeper riding tail from a rounded tail makes the whole ski ride deeper in the turn but a bit harder to keep the tip down. In the pull the sharp edge's lower drag is counteracted by the lift putting more of the ski in the water.

 

I slightly prefer the more rounded tails personally. But the tails seem to get rounded for aesthetic reasons - and the skis I spend (waste?) time on appearances are the skis that I tend to like the best fundamentally.

 

An interesting note, DFT hasn't proven to be overly sensitive to tail shape on my skis.

 

More important than tail shape has been a small (couple mm) kicker added to the last few cm of the tail. Reverse rocker? Magic? So many characteristics interact with each other that ski specifications relation to performance really is a trial and error thing.

 

Eric

[wilecoyote]

I'll add one more thing to Eric's analysis. The distribution of lift under the ski changes a lot with it's angle of attack. ie the higher the tip, the more the lift is distributed over the length of the wetted portion of the ski. When the tip is low, most of the overall lift will be concentrated forward on the ski. So from a theoretical POV, one would expect to feel virtually no impact from tail shape across the course, but some (very little) at the end of the turn where the tip tends to be higher.

 

Chris