Let's talk about flex

[skibug]

Mapple also made a ski that was hollow....it leaked too.

[Horton]

@kurtis500 We seem to have gotten off on the wrong foot. You would have gotten different responses from me if you had originally stated that you were a composites professional looking understand the state of water ski constriction.

 

Most current state of the art slalom skis are wet lamination around PCV or PMI core. Only Goode skis uses Prepreg at this time. All production skis are cured in a hard tool compression mold.

 

In the past there have been a few attempts to make slalom skis with a hollow core. These skis were less consistent in terms of flex and had leaking issues. It is cool stuff but no one has been able to make it work at scale.

 

Both longitudinal and torsional flex are critical. All ski have a progressively stiffer from tip to tail. Torsional flex number are not published by the ski companies and tend to be shrouded in secrecy.

 

Water skiers are more sensitive to flex / rebound than athletes in most other sports.

 

 

 

[kurtis500]

No problem, and I can see the response given I didnt lay out any information ahead of time. Pardon the long post but…….

 

I have spent my life on the long board race skis with double handles and enjoy the 20 mile long rough water rides at 45 mph+. Obviously a lot different than a slalom course. The slalom skier, I believe, is more in tune with stiffness because of the higher stresses around the turns. I have a relly nice wood slalom ski I occasionally get on for the fun of turning. I enjoy it also, but I know if I get in to another hobby sport I'll be throwing money at more recreational equipment. I have 8-9 variations of the long board ski already. (I stay away from mountain biking for this reason) The ski I have a mold of is more of a balance between the long board and a recreational slalom ski. Since the Andy Clark shape I molded isnt online here is one most like it. https://maherajah.com/collections/ski/products/67-classic-fastback-67clc1516

 

I like the saying ‘if it isnt broke, dont fix it’. I think both wood and liquid compression molding for skis today works fine. Foam cores and flexibility are a fine balance and are used in applications that can be fatal if not done right. https://hartzellprop.com/benefits-of-composite-propellers/ Stiffening primary components are usually done with m-frame, hat stiffening and etc. The problem for applying this technology to waterskis is the cost. Its simply not economical to autoclave or vacuum two components and then do a secondary bonding. The cost to achieve that level of performance goes through the autoclave with expensive tooling and isnt worth it for a ski company, especially when you invest in all that cost only to have a skier say ‘eh, I dont like it’. When you step in the 787 it doesnt matter if you like aluminum or carbon fuselages, you get a carbon one because its better. But you also get an ugly automated tape laid configuration and no cool graphics without adding painting.

 

[kurtis500]

.

 

[kurtis500]

No problem, and I can see the response given I didnt lay out any information ahead of time. Pardon the long post but…….

 

I have spent my life on the long board race skis with double handles and enjoy the 20 mile long rough water rides at 45 mph+. Obviously a lot different than a slalom course. The slalom skier, I believe, is more in tune with stiffness because of the higher stresses around the turns. I have a relly nice wood slalom ski I occasionally get on for the fun of turning. I enjoy it also, but I know if I get in to another hobby sport I'll be throwing money at more recreational equipment. I have 8-9 variations of the long board ski already. (I stay away from mountain biking for this reason) The ski I have a mold of is more of a balance between the long board and a recreational slalom ski. Since the Andy Clark shape I molded isnt online here is one most like it. https://maherajah.com/collections/ski/products/67-classic-fastback-67clc1516

Anyways, I also build heated composite tooling (molds) for composites using CAD and automation. There are many benefits of self-heated tooling but one relevant to this is the elimination of an oven and the ability to cure in an ASME pressurized chamber without the cost of an autoclave. I plan to take numerous approaches at this with the goal to develop the process.. not really build a better ski….but it will be nice too.

 

If you know composite fabrication you know the economics of a self heated tool inside of a pressure vessel will achieve autoclave quality without the cost. In fact, at a fraction of the cost with the same performance. The missing technology here for consistency and affordability is the heated tooling. So its always wiser to pick a product that can be improved upon or duplicated, doesn’t need qualified materials, inexpensive to produce and capable of demonstrating the process. I like the saying ‘if it isnt broke, dont fix it’. I think both wood and liquid compression molding for skis today works fine. Foam cores and flexibility are a fine balance and are used in applications that can be fatal if not done right. https://hartzellprop.com/benefits-of-composite-propellers/ Stiffening primary components are usually done with m-frame, hat stiffening and etc.The problem for applying this technology to waterskis is the cost, IMO. Its simply not economical to autoclave or vacuum two components and then do a secondary bonding. The cost to achieve that level of performance goes through the autoclave with expensive tooling and isnt worth it for a ski company, especially when you invest in all that cost only to have a skier say ‘eh, I dont like it’. When you step in the 787 it doesnt matter if you like aluminum or carbon fuselages, you get a carbon one because its better. But you also get an ugly automated tape laid configuration and no cool graphics without adding painting. The high processing costs, secondary bonding, painting and you cant make it look ‘cool’ out of the mold are my educated guess for the reason nobody does it. So I’ll be doing it as a part of development.

 

I probably should have asked ahead of time about the best boot but I purchased the HO xMax and freeMax bindings for the prototypes. They seemed to fit well and comfortable when I tried them on. I’m guessing these are decent boots in the industry?? These will be double bindings skis also.

 

 

 

 

 

 

 

 

 

[kurtis500]

.

 

[kurtis500]

 

.

 

sorry for the dots, was having a lot of difficulty posting more than a paragraph since the 'Save Comment' button kept scrolling off the page.

[Horton]

@kurtis500 I apologize for the editing issues. Developers are working on it as we speak. Next time you have that problem simply take a breath and wait for it to autosave and then refresh the page. Your last edits should be there and the post button will be there also.

[bigtex2011]

Man I wish i were an expert at something other than being a smartass. @horton your junk must be a little bruised after getting them kicked square in the burrito.

[Horton]

@bigtex2011 no

[wawaskr]

Who thinks this would have some crossover potential to water skis?

 

https://renoun.com/pages/technology

[kurtis500]

.

[kurtis500]

After watching a lot of tournament ski videos I have another question about flex...

 

In terms of tip to tail flex (not torsional) does a rider prefer flex in the area BETWEEN the front toe and rear heel or NO flex? It seems like the aluminum plates bolted to the board allow a little flex between the front and back foot..?

 

Curious minds want to know.

 

[coach3]

@kurtis500 That is a great point. I slightly loosen the very back of rear and front of front screws just a bit to allow the ski to flex, although I have never flex tested with boots and using this method vs torquing them all down. I also have a homemade Wileys type rear that flexes in the middle of the boot. It would be an interesting test. Rebound could also be dampened with a very stiff and tight binding set up, just don't know.

 

However, using my method, checking screws each set is important.

[VONMAN]

All ski's loose flex and rebound over use and time. They break down. Now that I've roll the hand grenade into the room, I have a story to tell. Many years ago, back in the mid eighties I bought a O'brian TRC, very fast cross course but don't get on the tip at the turn. Had it for two seasons and it took me to the world of 32 off many times. So two years after I bought it I walk into my local ski shop and in the corner is a brand new never been used TRC same model and boots. I bought it and out to the course we go. What a difference, night and day difference. Faster, easy, less work, born again skiing! I had a similar experience with my first Goode 9100. I dropped it off the get the bottom repainted, Goode flex tested it and gave me a new ski to replace it with. Wore it out in one season.

[Horton]

Remember that there is a team that is developing the skis at each company is riding the skis with ( some sort of ) binding plates. Worrying about what your binding plates do to your ski flex might be a little bit folly

[kurtis500]

Seems like an aluminum plate bolted to a flexible ski will stiffen the ski under the foot.

 

Another way to ask the question......is the space between the rear heel and front toe preferred to flex with the ski or be as rigid as possible and let the ski flex more in front and behind the feet?

 

Whats the quick answer for why the skis loose rebound and flex?

[MattP]

@AdamCord care to chime in?