What causes skis to break down

[lakeo]

In your considered opinions, how many sets is the average ski good for? We have all heard the stories of skiers on 10 year old skis who knock out 39 off, but in general people switch skis every ... how many years? I am experiencing a goode 9960 which has been a great ski carrying me into 38 off but of late has become very inconsistent. Yes, I know it could be the indian. Finally, do you think certain brands are more or less susceptible to breaking down?

[Horton]

If you ski at a high level (and it sounds like you do) at the end of 2 years the ski is simply not as snappy as it was when it was new.

 

We have all heard stories about the 10 year old ski that is good as new and you also hear stories about 6 month old skis are are dead. These extremes are not the norm.

[DW]

People with more expertise than I can add better insight, a few thoughts on ski performance degradation reasons include: core material or core bond breakdown, main material breakdown where carbon seems more sensitive especially if left exposed to heat over time or some external damage inflicted on the ski causing a weakness to develop in the area affected. In addition, the amount and number of flex events certainly contribute to a ski wearing out going to JTH's comment above.

[andjules]

Just a reminder to frame this in terms of sets, not seasons. @Horton your season has A LOT more sets than mine!

 

Side note: A couple of seasons back there was a 'legends' category at... was it Diablo? Anyhow, if I recall correctly, Carl Roberge came out on his old CR7 and ran into -39 @ 35mph!

[lakeo]

I have in the neighborhood of 250+ sets(8 passes) can't exactly without my log.

[mwetskier]

in my experience the major cause of skis breaking down is baggage handlers.

[walleye]

I was told this year by Dave G that his skis never break down. I was shocked and so were others. It would not be to his advantage to say this, it was quite a large number of skiers he said this to. This does not include damage or reverse flex which he said was worst thing for carbon fiber.

[mwetskier]

@walleye -' never ' is a very long time. did he offer to have santa or the easter bunny corroborate his claims?

[thager]

My favorite ski is an 07 Fischer #01 that has a huge number of sets. Not sure if it was originally soft or if or if @RazorSkier1 made it soft but it sure works for me. Lot to be said for RTM construction. Problem with carbon is it doesn't warn you. When it goes, it is a catastrophic failure. I believe Jeff Rogers record was set on an older ski.

[walleye]

No but he did give us all T-shirts which was cool.

[walleye]

@thager Dave quoted that very record when Rodgers went back to a very old ski.

[AdamCord]

Plastic Fatigue. @DW pretty much nails it. A ski has 3 main components: Carbon, Epoxy, and foam Core. The core and epoxy are both plastics, and plastics will fatigue over time with repeated strain. The shear loads on the core are very high, and many cycles reduce the elasticity of the core/epoxy and their bond.

 

Some skis will last a long time because the laminate is better bonded to the core, meaning the shear load is spread over more molecules. Other skis that have a weaker bond to the core (meaning there is less epoxy attached to the core surface) will break down faster. The reason a ski like the Fischer will last longer is twofold: it has an almost perfect core-laminate bond (no air pockets) and also some of the shear load is carried through the sidewalls because of fiber orientation and how the core is wrapped over the flash line.

 

Of course there are variables like type of epoxy, type of core material, UV exposure, temperature changes, etc, but that pretty much sums it up.

 

The carbon fiber itself fatigues but those fatigue tests are in the millions of cycles. The core/epoxy will break down long before you get there :)

[MrJones]

Outstanding explanation Adam. Thanks..

[kstateskier]

Outstandingly Nerdy explanation @AdamCord‌. I like it!

[gsm_peter]

A fiberglass laminate continiously keeps hardening.

One can measure an old boat bottom.

I have seen up to half an inch concave bottom thst was originally built straight.

Also as very well described above laminates becomes softer when older.

 

Gd night from Sweden!

This time with a US friend from CA Palm Desert :0)

[Ilivetoski]

@walleye its funny you say that about Dave Goode. I know one guy who just got back from over a month from Europe. 1st week he was there his brand new XT broke. That is the reason I stay off his skis. Well that and I refused to ski on the velcro. Seen some pretty bad pre releases.

[ozski]

Yet another story of a broken Goode, I've heard / seen a couple here this past season. I think that is part of the reason why they don't sell many over here.

[ALPJr]

Lifetime warranty http://www.connellyskis.com/product/connelly_slalom_prophecy_ski

[walleye]

@ilivetoski Sorry to hear about your bad experience Goode XT. Adam gave a very good explanation of what breaks down in skis. The quality of workmanship (sealing/bonding) doing the resin part is huge for all ski Mfg's. I believe D-3 and a skier named Nate used a ski for better than 6 years and set multiple records. Sun exposure, reverse flex and structure damage (usually transporting) cuase skis to break down. I shared a 9800 with a guy for 6 years, I did notice the final year it was not as fast thru the wake. What I have noticed with carbon ski/fishing pole, if you get a good one it last along time provide you take care of....Not saying there are not bad ones as many have had bad experience. More than once I have witnessed drive X miles walk in x miles first cast the tip breaks on a Hi dollar Loomis....Not me though still use the St-Crouix my wife bought me 15 years ago. I have beat it to death thru brush rock many of falls at night caked with ice just saying :)

[AdamCord]

@kstateskier I'm glad I can spread some nerditude around the forum every now and then.

 

@walleye I've heard multiple people say that about reverse flex. Do you know where that comes from? It doesn't really make any sense to me. A ski is basically a glorified sandwich panel with carbon laminated to both sides of a piece of foam. The only difference is that normally the top skin is made thicker to reduce the chance of breakage by buckling since carbon is not as strong in compression as it is in tension. So most skis will break more easily in reverse flex, but that doesn't mean that some amount of reverse flex will really speed up the breakdown on a molecular level.

[walleye]

@adamcord I know nothing about carbon, you do. It was told to me by Dave who said flexing skiis in reverse direction is bad. Not sure if Dave was refering to the Carbon, epoxy or what??? You being in the industry know far more, mine is just one mans opinion not even my own just hear say. What I do know Dave makes some very good:) skiis that are proven by all the championships. I have had very good experience with them, I own 5 of them with no problems. Let's have a match race and turn Nate loose on one and see what happens:). That would be fun!

[walleye]

@Horton How about a Mfg's challenge Nate on a Goode with snitz and Lapoint making adjustments.

[thager]

@AdamCord Would taking the foam out of the ski's construction reduce the rate of breakdown then?

[AdamCord]

@thager Theoretically yes, so long as the shear loads are distributed in a way that it is carried fairly evenly by the carbon and there are no very high load concentrations. The Warp is a good example of how this could be done. I have not seen any of the newer Warp skis but I know some of the old ones had issues with cracking along the ribs in the ski (there are 3 vertical ribs running tip to tail, which along with the sidewall, are designed to support the top and bottom skins and carry the shear loads). I believe the cracking was a result of stress concentrations where the ribs meet the top and bottom surfaces.

 

@walleye You love that orange koolaid, eh?

[walleye]

@AdamCord love orange koolaid but hate how much it cost:(. My future is looking bright though. The wife is ready for another ski which means her and both kids will all be riding it...IE traveling with one ski instead of 3:)

[thager]

@AdamCord I am assuming the Warps are compression molded skis. Is there a way to make a hollow RTM ski?

[Horton]

@thager‌ Warps are built in an autoclave

[SkiJay]

... cooked in an autoclave, not built in one. An autoclave applies heat and pressure to the nearly finished ski after it has been assembled.

[BraceMaker]

My goode met its demise when we had a nice 90 degree day with no shade. A few ski rides later and the bottom layer of the ski had a void under it which then cracked.

 

No really degradation but thermal failure.

 

So what are the main processes?

 

Wet lay up/molding - wrap core in fiber, brush w/ resin, wrap with more fiber, brush, insert into mold - press/cure?

 

Hollow core skis - I assume with these they mold a top deck, a bottom deck, and stringers, and then assemble each component together to make a finished ski?

 

RTM - I assume this is where you put all the components into a mold, compress and pump resin through the mold?

 

 

 

 

[MISkier]

@BraceMaker‌ , go to YouTube and search "How a slalom ski is made". There is a 4:56 video of Strada construction. It may not reflect how all skis are made, but it answers some questions.

[Horton]

@jayski‌

You think that anyone who knows what an Autoclave is does not know what I mean or anyone who does not know what an autoclave is now knows more.

[thager]

@Horton Yes, what you said.......????

 

 

[eleeski]

I've broken more skis than anybody. I push the weight to ridiculous levels so my skis are right at the strength limit. If they don't completely break, they should break down noticeably - if breakdown is significant. For me, my skis don't fade with time - now.

 

Early on, my skis would change over time. Crappy epoxy creeped. Wood warped. Aluminum honeycomb corroded the core. Urethane powders with flexing. Carbon is weak in compression. The performance of the skis would change - and then they would break. Yes, skis can age.

 

Material selection can address most of these issues. Applied Poleramic epoxy is fantastic and solved my resin issues. PVC foam is stable and strong. Clever engineering and/or Boron fibers solved the carbon compression weakness. Fixing the problems allows the skis to age well.

 

My skis certainly do get stale. They seem to lose snap and acceleration. A new ski can really improve my performance. Especially when I go through the final dialing in of the ski. All the assessments of adjustments seem to really help make me ski better on the new ski. But I have come back to some old "broken down" skis and found fantastic performance in the resurrection.

 

As far as technical reasons for ski degradation, mechanical breakdown of the flex is not the only (or even the main factor). I wonder if anyone has documented flex changes over time with a flex tester. Base texture seems to change, either with little scratches happening or the roughness wearing down. I will often redo my texture to rejuvenate my ski. Another serious wear point is the edge. Critical for the feel of the ski. Each time in and out of the bag, boat rash and even the rope on startups takes its toll. Note that the top edge is relevant. Even little aging factors like finbox or binding screw tightness can have a noticeable effect. Little things can add up enough to be noticeable. New skis rock! Plus new skis are just plain fun.

 

Eric

[jayski]

@Horton ... @SkiJay‌ not @jayski once again, you ever been diagnosed with Dyslexia?

 

[SkiJay]

@jayski‌ Dyslexia with a dash of hypersensitivity. Why the slap @Horton? Sheesh . . . .

[gator1]

He's in the sleep deprivation stage of new fatherhood.

[eleeski]

@Horton‌ ??? An autoclave just heats under pressure. A mold is still needed and many different processes can take advantage of an autoclave.

 

Warp's coreless construction does need a complex mold and molding process. It is innovative but debatable whether lighter, stronger and more durable. The technology has been around since the 70s (Durafiber snow skis and Maherajah water skis). And many factors matter when determining how well a ski performs. Or holds up.

 

Eric

[gator1]

@eleeski‌ how do you rejuvenate bottom texture? Wet fine sandpaper? I've noticed some shiny spots on my rails and have started obsessing about laminar flow.

[Horton]

Dyslexic yes

@SkiJay‌ you were correcting me.. no stress... or more accurately quick responses on my phone sound much grumpier than I intended. and yes I am sleep deprived thank you very much

[BraceMaker]

@MIskier - yes that's where I was commenting on wet lay up. You have a core wrapped in fibers, a technician then brushes, pours/squeegies wet resin into the layers and then crams the whole thing into a mold, puts it under pressure and lets it kick off and cure.

 

But that's the most basic of methods.

 

Goode shouldn't be made that much differently than the strada, only the material is "prepreg" or comes already soaked in resin which is kept from curing by refrigeration. So the technician layers already cured materials into a mold, inserts a core, more layers, closes the mold, pressure and cure.

 

The main difference is that prepreg materials tend to be more consistently saturated and the Resin should be stronger. Atleast with what I do we view prepreg laminations to be more structurally strong per weight due to a few factors.

 

I get foggier on the difference in RTM and in how a coreless ski is made.

 

I'm still of the assumption that coreless skis are made in parts and assembled instead of molded in one shot - otherwise you'd have to have some form of core which could be desolved/heated out, like wax/foam - then plug the hole.

 

My assumption with RTM is that the material is placed in a mold dry and resin is forced through the mold while a vacuum is applied - but I'd love more detail.

[mwetskier]

autoclave sounds very high tech maybe too high tech $$ for water skis. the first skis andy mapple made as a independent manufacturer were hollow and no autoclaves were injured or killed or even plugged in during the building of those skis.

[Horton]

@eleeski‌ I think autoclave is impractical for mass production but I believe for super high end motorsport and aerospace applications it is 1 of the preferred methods

[eleeski]

@gator1‌ I actually prefer a rather rough texture on my skis. I scratch the surface with 40 grit sandpaper as my final surface. When this gets dull, I can easily scratch it again. If there are unwanted scratches or damage, I will fill with either JB weld, Superfil or paint. I might need to sand with a bug sander and 100 grit before painting.

 

When I try a slick finish (wet sanded 220) the ski gets both slippery and sticky. Both slalom and tricks. Sharks have some texture on their skin to minimize drag so my preference of roughness has some basis. Didn't HO offer a fancy bottom surface? Besides, life is too short for fine sandpaper.

 

Comet or Ajax works well with localized gloss, wax or grunge.

 

Eric

[eleeski]

@horton The word autoclave is used too specifically by you. I built an autoclave to cure prepreg for really cheap. It worked quite well. Heat and pressure are not that exotic.

 

I had trouble bonding my prepreg to the core. Wet resins made a better bond - dry prepreg made a better skin. I had good luck with a mix. But I now use dry cloth and wet resin in a room temperature pressure mold.

 

I had an interesting conversation with Will Bush today. He claimed that the skis he measured got stiffer with age. Makes sense as plastics (epoxy) get more brittle with age. Overloads or defects would make a ski age softer but normal use should not break down a ski.

 

Your technique breaks down with too much familiarity with the ski. New skis are fun and challenging but not structurally better - unless the manufacturer has developed a new technology.

 

Eric

[Wish]

Is it weird that I want to sit down with @eleeski‌ for several hours just to pick his brain? I'd bring the beer.

[Horton]

@Wish lots of beer

[Dusty]

Q.- Was there a kind of threshold date that skis began using particular types of cores that are more resistant to heat degradation? Reason I ask has to do with a Duvall that I owned- Didn't hold up for a whole season- several skiers suggested it was due exposure to sun/heat- it was nearly unskiable by September. Much softer flexing than new. Maybe some other factor was in play?

[eleeski]

I put some black prepreg in the sun with an embedded thermometer. 170F! Way over the rated maximum for that resin. Ended the solar autoclave project.

 

I threw a black painted ski in the back of the convertible on a pleasant sunny day. A few hours later when I arrived, the bottom skin had completely delaminated.

 

Rapid extreme heat is all too common and causes significant damage very quickly.

 

Paint the ski white.

 

Eric

[skialex]

@eleeski‌ you are really great with your R&D and all this ski related knowledge, I keep my skis away from the sun at all time, use a fleece cover or a towel when I'm on the dock before skiing. Direct exposure is what kills the carbon, temperature does not rise if ski is covered.

I too like to freshen the bottom of my ski when it gets slicky, I use SEM classic clear or black or any other color, fillers for the big scratches, scotch bright, sandpaper and make the ski look like and ski like new.

[skialex]

I have changed my mind, I just got in the car which was under the sun for about three hours and the ski (with a ski cover) that I had left inside was super hot, not my ski!