I'm Going to add speed steps to my Ol' HO A1

[ThePantsManCan]

So, I've got the time this winter to do pointless things to old gear. I sure do like the speed steps of my S2. I'm gonna add the steps to the A1 regardless of any suggestion to the contrary. I'm sure it won't ruin the ski. Now my trouble is...

 

What epoxy/resin/hardener should I use? What sticks best to a properly prepped ski bottom. The material to be used need not be clear as I plan on coating the final product in the Goode SEM Bumper Black.

 

Suggestions?

[Horton]

@AdamCord

[Horton]

you want Adam to comment but I think all you need to do is rough the surface with maybe 80 grit and use bondo.

[ThePantsManCan]

@Horton, I sure could use bondo. Maybe that "Bondo Hair" product with the short fibers. I just want the final product to last more than a few sets. I guess that is why I am leaning towards a two part plastic material that is more similar to the actual ski.

[ThePantsManCan]

Presuming that the bondo product wouldn't take a lot of flex cycles??? I dunno.

[AdamCord]

Bondo is the way to go. It's very easy to shape and it sands much better than any kind of epoxy/filler combo.

 

Just rough up the surface and clean it with acetone. Be sure to do a really good job masking. Otherwise you'll end up with bondo where you don't want it and its a pain to get it off again.

 

Also if you've never used bondo before you want to mix small batches instead of trying to make one monster batch. The ectotherm will kick it off before you finish mixing.

 

Good luck man, I'm always glad to see people trying new things on water skis. I'd also recommend you read up on stepped hulls on boats and airplane floats. Let's just say that if I were to put steps on a ski I would have done a few things different than how HO did it...

[ForrestGump]

Use bondo. I've seen Mapple and the Lapoint's use bondo to change a ski shape before. It's actually fairly flexible. Rough the area that you're going to modify with 50-80 grit sandpaper. Once you feather it out with 220grit, it'll blend right into the base.

[ThePantsManCan]

Sweet! @AdamCord @ShaneH, I have plenty of experience with Bondo! If the master shapers are using bondo for prototyping, then I'm sure it will be good enough for me. I just thought the ski crafters would have some secret recipe they often used to make adjustments.

 

Look forward to some pictures of my progress throughout this winter!! Thanks guys!

 

PS @AdamCord, got any 67.5 Quattro skis lying around???

[AdamCord]

Exotherm. Stupid autocorrect.

 

@ThePantsManCan sorry I don't have one of those! No one gives me free skis anymore unfortunately.

[ThePantsManCan]

Ouch, where's the love, ya Kno?

[AdamCord]

I have a bad habit of just chopping them up and reshaping them anyway...

[ThePantsManCan]

Good point. Then again, if I had your skills, who would need free skis? I really appreciate your recommendations.

[ToddF]

hopefully I am not the only one who doesn't know what a speed step is.

 

[Wish]

[eleeski]

@ThePantsManCan Not Bondo! It's heavy, weak and kicks off too fast. Superfil is a microballoon epoxy mix that is extermely light, sticks well and is really easy to sand. It will take a lot longer to do the job as it can be worked for an hour and takes overnight and warmth to cure. Bondo is OK for skim coat finishing as you can do a couple of thin fills quickly. But I don't have good luck with major amounts of Bondo. Superfil builds up quite well for my applications. I'm not sure I modify as many skis as Adam but since I have to build all of mine from scratch, I'm much more apt to slop a lot of filler in an effort to salvage a sketchy ski or try a crazy idea. Plus, I'm a weight fanatic and Superfil is light. Aircraft Spruce has Superfil online.

 

Wallboard texture!

 

Eric

[ThePantsManCan]

@eleeski, I will take that into consideration. If it is easy enough to work with or at least as easy as bondo, then I can get some and to a small test on a busted ski first.

 

I took @AdamCord's advice and studied a little about stepped hulls. Of course, now my little project will become infinitely more complicated. I remembered a while back, I read an article about the lift generated by the leading edge of a whale's fin/flipper. The leading edge is not straight but serated. The bumps on a whale's fin are called Tubercles.

 

I might turn the "Speed Steps" around and make them bumps. Serated bumps that step in the opposite direction than the steps on an HO S2 or Connelly Prophecy.

[Horton]

remember that as the tunnel gets shallower the ski gets faster and has less grip. you may also be changing the tunnel rocker.

[CsSkis]

@The PantsManCan

 

Whoa...forward facing bumps! You might/should reconsider that. Those bumps, even with very little forward facing area, will markedly increase the drag of the ski.

 

I would guess that a whale's tubercles are a natural form of vortex generator - intended to help with laminar flow on the fin/flipper. For all intents and purposes, a waterski does not experience laminar flow.

 

Oh, and here is a link to an article that Adam and I have discussed in the past:

http://www.navaldesign.co.za/articles/Stepped%20Hulls-%20Feb07.pdf

[skier2788]

I played with the bottom of my RS1 last winter. I used the fiberglass bon do filler. I've done a lot of body work so I was used to shaping and sanding it. Biggest thing I noticed was it made the ski stiffer which is good for a big guy like me. My dad actually switched from his senate after he rode it. Skied only a few weeks on it at the end of the summer so can't speak for durability of it for more than a dozen sets

[Jdubs]

JB Weld is the epoxy I always use on any ski, but you are going to change the entire dynamic of the ski.

[ThePantsManCan]

I figured that if I kept the steps small/short, as in no higher than a 16th or so, and always tapered the step down to the original ski surface, I would only change the concave a little bit. That's my plan. Each step will end at the original surface, where another step will begin. Perhaps I should have a look at a shark's gill...

[Wayne]

Just a question out of curiosity, did any ski manufacturer put "golf ball dimples" on a ski bottom? I thought I saw this on a wake board a number of years ago but wasn't sure about a ski. The dimples were shallow but had a large diameter, maybe the size of a quarter. Is this a been there done that and it didn't work thing?

[CsSkis]

@ThePantsManCan Please read my previously linked article on how/why stepped hulls work before you invest much time/effort on a stepped ski. If you really want to start tinkering with your old ski, start thinking about how bevels work and how different bevel shapes change where the flow separates on the sidewall of the ski. A round bevel creates more suction and a sharp bevel reduces it.

 

@Wayne Always ask - what is the change in the surface supposed to do - is it marketing, or is there a real reason for the change? My guess is that the dimples were there for marketing purposes.

[Intheday]

@wayne the dimples were on a HO Turbo Trick Ski

[bbirlew]

The dimples were also on the original hyperlite wakeboard but I don't believe I have seen them on one since.

Marketing suggested they helped the board release from the water on take-off and cushion the landings.

 

I have my old board sitting in the garage, but the board is so different from a modern wakeboard that you really can't compare. (Ie. thick sidewall with 45deg bevel more like a slalom ski; directional instead of twin tip; foot straps with fixed position instead of ducked out adjustable bindings, etc..)

I'd guess that since they haven't been on a board since, they either didn't work or they had some negative trade off that wasn't desirable.

 

Obrien used to do some funky things on the bottom of their skis back in the mid 90s. I believe it was the G3 that had the 'Venturi tunnel' - a narrow tunnel up front opening up to an edge to edge tunnel behind the rear binding.

[Wish]

From Connelly. Looks like they tried a few variations.

 

Ski bottom technology has been stalled for too many years. We wanted a 34 mph ski that worked better for the skier than any of the old designs on the market. Stepping outside the box we started testing steps in the tunnel. Straight steps, angled steps, steps that roll up the bevel, stopped short of the edge, 4 steps, 5 steps, etc. Our testing and performance on the water validation confirmed that 6 V shaped steps is far superior to any other design. These steps grace the edge-to-edge tunnel of the ski, which reduces drag and helps speed with less wetted surface area. The result is a smooth quiet ride that is freer in the turns and quicker reacting. A narrow tail sits deeper in the water creating a more symmetric turn and less bounce across the wake. This is the smoothest most forgiving 34 mph ski on the market.

[thager]

Golf ball like textures go back to the late 70's or early 80's. Kris Lapoints tunable ski had a dimpled bottom texture. @bbirlew Torque "Super Comp" had the first advertised venturi tunnel I can think of. EP had their version and Western Wood had the "Funnel tunnel". None of them worked worth a darn!

[lpskier]

@ThePantsManCan If I am not mistaken, experimental tubercles are called testercles.

[ThePantsManCan]

@lpskier, BAAAAAAAHHHHHHAHAHAHAHAHAHAHAHHAA!!!

[bogboy]

@ThePantsManCan, neat idea, I wonder if adding step material , proud of the bevels would change handling.

[ThePantsManCan]

I like that Idea. I don't want to change the bevels. But adding the step right across and over the edge intrigues me. Plus, I can always take that material away if I don't like the effect.

 

Also, as Adam Cord was saying to do, I took a look at a step hull design for boats. The studies found that if you bury a step completely in water, it will not be able to draw air into the step, creating sudden suction. If I build the steps proud of the bevel slightly, perhaps I can negate that effect.

[CsSkis]

@ThePantsManCan I'm glad that you understood about requiring air to ventilate the step and that carrying the step around/over the bevel might alleviate the suction. Unfortunately, a waterski is much more complex than the planning hull of a boat. Boats are typically going in a straight line (traveling point-to-point). Running a slalom course is just one linked turn after another. If you look at any picture of a waterski as it is passing through the water (cross-course or otherwise), either one side or the other is always immersed in the water from about the front foot to the tail. So, what would be the purpose of adding steps?

 

There is something else about boats versus waterskis. When a boat is on plane, most of the water molecules are traveling longitudinally under the hull. There is some bow and hull spray, but most of the water is passing under the hull. However, and we are all proud of this one, slalom skiing is defined by the spray we generate! The spray is a graphic way of showing that a large proportion of the water molecules are travelling more laterally (typically, about 30 degrees) across the bottom of the ski. (Refer to attached picture of Rossi)

 

There is one point at which the waterski is acting similarly to the planning hull of a boat, but it is very, very, brief. It is during the edge change. (Refer to attached picture of Smith) The ski is unloaded at this point and the planing attitude reflects that fact. However, it also occurs in the "whitewash" which is already well "ventilated". So, steps wouldn't contribute to a lowering of drag at this point either.

 

Food for thought.

[CsSkis]

@Wish I don't know how to comment on Connelly's information. The biggest question that I would ask is what kind of "tunnel" test they used and how the testing was conducted. It would be nice if they published a technical report on how they did it. Up to this point, I am not aware of any formal, lab-based, testing that could replicate how we interact with a waterski and determine what does and doesn't work in a slalom course. (I wish there was!!!) And, when Connelly talks about validating it on the water... testing a waterski is, to all intents and purposes, based on highly subjective feedback. Just ask Horton!

 

Does it sound like I think that I know everything? I hope not, as it gets proven to me every day of the week that I don't!

 

Just for fun, I have attached a picture of the spray off a ski that was being tested a few years back. The only "data" I acquired on how it worked was all based on subjective feedback. However, it turned out that fin tuning was a stronger influence on the feedback than the design of the ski itself.

[Wish]

@CsSkis I just put that in there as perhaps a way to shorten the learning curve. I agree with you. Subjective at best. But, they seem to be the only ski company laying claim to having attempted different styles, sizes, lengths of steps. HO has not. And I'm not sure anyone else has even tried although I do feel others will. I am a guy that fiddles with all kinds of stuff on a ski for the sake of learning. I can honestly say that I think changing the steps shape, length and the like could certainly be felt as a positive or negative and changes could be made accordingly. Just think of the stupid small amounts of boot, fin an wing angle changes we make these days and the crazy difference it makes. If I was gonna do this to my ski, I'd be making them similar to Connelly and hedge my bets based on what they seem to have gone through.

[ThePantsManCan]

Has anyone ridden the S2 and the versions of the Prophecy with speed steps side by side? Which ski design seemed easier on the body? I know Horton has, but his ski tests were quite far apart I'm sure.