AdamCord

@Horton they are "speed wrinkles", and the help turbulate the water flow. Worth 3 buoys at least.

@Jordan yes it makes a big difference. This is part of why I like the free expansion method better than forming the foam under pressure. Expanding freely like this I will have a more consistent density. This foam I use will be 8lb/ft^3 when left to expand free. If I had it under pressure it might be 10 or 12 lbs. To compensate I would have to use a lighter foam to begin with.

Ok so we're ready to make a core. Now as I said before I have never tried to make a Polyurethane core this way. Normally I've done it either with a dedicated core mold and press (the way it's done in a ski factory), or in a mold like mine in a ski press. The reason you need a press is that when the foam starts to expand, there is a LOT of pressure. Also you need the closed mold to force the foam to expand into the tip and tail, working against gravity. I could try and clamp a top to my mold, but the pressures would probably cause the mold and/or top to deform. So for this method I am taking a new approach. I want to let the foam expand freely in the mold and also up and out of the mold cavity. Then after it is cured I can cut/sand the excess foam away. There are a few problems with this approach. First the poured foam is a liquid, so gravity is a problem. I solve this by doing multiple pours with the mold tilted at different angles instead of doing the whole core in one shot. The second issue is that by freely letting the foam expand from the mold it may not fill out the top edge well, and also I have no reference for where the top of the core should end. I solve this by using plywood to make a small overhang around the edge of the mold cavity. See the pics below and it will make more sense. Here is the offset insert I made sitting in the mold I then used spray adhesive to put the 5mil visqueen into the mold Here is my top that will overhang the mold cavity by about 1/2" but still leave the center open to allow the foam to flow freely And here's that board also wrapped in visqueen and clamped to the top of the mold. I poured the tail section first. This stuff expands very quickly so this was hard to the touch in maybe 5 minutes Within 5 minutes I poured the tip section. This is quick enough that the first and second sections should get a good chemical bond I then put my "oven" box over the top and let it cure for a few hours. The foam fell right out of the mold because it doesn't bond at all to visqueen But this is where we can see where it all went wrong. When I've done this before in a press, the closed mold and pressure from the expanding foam didn't allow the visqueen to wrinkle at all. This time the foam was just freely expanding and there was no positive pressure. I am not sure if it's because of a chemical softening caused by solvents in the foam or from the exothermic heat, but the visqueen wrinkled a LOT. Those wrinkles were transferred to the foam. So my nicely formed core looks like a raisin on the bottom, which just won't work Luckily once it's all set up it only takes about 15 minutes to make a core and this is maybe $10 of foam, so not a huge loss. My new plan is to use packing tape instead of visqueen. I did a really quick test and the packing tape seems like it will work. The lines you see are just cosmetic from where I poured the foam, and not wrinkles in the surface. I'm planning to try this again with the packing tape instead of visqueen and I'll report back!

I've gotta say this may be the first water ski design/marketing video that I've ever seen that isn't pretty much all BS. @JoelHowley clearly is a bright kid and everything he says in this video makes sense, which is super rare for ski marketing. Normally I watch videos like this and just shake my head. All the explanations he gives on how the ski shape effects the on water performance are spot on. Now does that mean the ski is any good? I have no idea, but at least the ideas are sound and he didn't just make up a bunch of BS! :D

@skiray I buy most of my bagging materials from ACP here in the US. Anyone who wants to learn the basics for all this stuff should watch the Easy Composites videos on Youtube. The one about the car hood is probably the closest to the process I'm using. Those guys do a really good job of explaining and I wish their videos had been around back when I got into this hobby.

@oldjeep if I were building for mass production it would matter a lot. I would want to bring the ski up to a very high temperature so it cures more quickly. With short cure times and high temps I would need to keep the temps very consistent so I don't undercure anything and so I don't overheat anything. But for this operation I have all the time in the world, which simplifies things a lot. I can cure at lower temps for a long time and never have to worry about getting too hot or undercuring, even if one end is hotter than the other.

@Wish here you go > US Cable Parks I agree with @jcamp. And this could go along with the cable wakeboard in the Olympics discussion. Growth in cable wakeboard is GOOD for us! I wish every major city had a cable park. If I could figure out how to build a cable park here in NYC on the Hudson (and convince people to get into the water), I would. Water skiing will never be as big or bigger than wakeboarding again, especially with cable parks being built all the time, but is that a bad thing? Wakeboarding is our putt putt course. It's our gateway drug. Our sport is expensive as @Horton pointed out. Many people will just never be able to do it. But cable brings the barriers to entry way down, and opens watersports up to the masses. We need to get behind this in a big way. Think about sites like OWC in Orlando, Trophy Lakes in Charleston, Bow Lake in Washington, McCormick's in Tampa, etc. These are sites with cable AND a boat lake. Sometimes the boat lake pulls wakeboarders, but more often than not it's skiers. It puts skiing right in front of the masses who are now being introduced to watersports because of the cable. We need more sites like this. 2 point and even full cable systems actually take up a surprisingly small amount of lake area. Many ski sites could accommodate cable and skiing! Or if you've got some room to dig it wouldn't take much to make room for it. The 2 point systems don't need much space at all. I honestly think cable systems are our way forward, we just need to understand that and take advantage of the opportunity instead of turning up our noses. Also if you've never ridden the cable it's super fun. You can do it on a trick ski if that makes you feel better about it!

Also as a side note - I used the same wax on the mold that I had used on the plug. This time however I brought the mold into the warm house to apply the wax instead of doing it out in the cold. I also did about 8 coats, where as I think I did 4 or 5 on the plug. The wax performed perfectly this time and the insert basically fell out of the mold, which is exactly what it's supposed to do. So the lesson here is apply the wax at normal temps and use more coats than you think you need!

I plan to cast the urethane foam core in the mold I've built. This will leave me with a part that is exactly the right shape. But the carbon fiber has thickness and the core surface must be offset to make room for that thickness. If I don't account for it, the core and carbon won't fit in the mold. It's important to have a very consistent offset because I need a consistent pressure on the carbon laminate when it's being infused under vacuum. There are a few ways to do the offset. I could just cast the foam and then try to sand the surface back, but it would be very tough to do that consistently and also sanding sucks. What I did was make an "insert" that drops into the mold and has the thickness I need built in. This way I can drop the insert into the mold before making any cores and I'll have a consistent offset. I know that my carbon laminate will be somewhere around .040" thick depending on the layup. I used 4 layers of ~.008" thick fiberglass and some cheap polyester resin to make a quick, cheap insert. Here is the fiberglass sitting next to the mold I didn't get any pics of the layup process because this stuff kicks off fast and also I had sticky resin all over my gloves. But to give you an idea I wet out the first layer on my table, then put the next layer on top of that, wet it out, and so on until I had 4 layers stacked up and fully saturated. Then I put the entire stack in the mold at once, and carefully pushed it down into the bevels. I used my fiberglass roller to get all the air pockets out between the fiberglass and the mold. On top of that I put down some perforated release film, then breather fabric. Lastly I put a vacuum bag over the top of that using vacuum tape. I pulled vacuum until it was cured. This is what it looked like while under vacuum I then popped it into my awesome $10 oven ($30 if you include the cost of the space heater, which I already had) to let it cure. This little oven will get the whole part up to 150 or 160F. Then after removing the bagging material it looked like this I then spent some time trimming off the flash and sanding down any high spots. There were a few areas where the fiberglass didn't lay down perfectly so I needed to sand those to get a consistent thickness. Here's the finished insert This came out to right at .035" thick, which should be perfect. When I make the core I will put this in the mold first, then I'll put a layer of .005" visqueen over it. The foam won't stick to the visqueen. Also later if I decide I need more offset I can just add another layer of visqueen or use different thicknesses.

@Horton if you read his posts about accelerometer data capture then you would know the answer to that question. @tap and I were roommates at Purdue. He's the guy who probably should have gone to MIT but he liked waterskiing and the waterski "lifestyle" a bit too much for that ;) @tap fair enough

Yeah I can't take credit, this is @tap's idea. I plan to blame him if it doesn't work.

Moving the boots laterally definitely makes a difference. It changes the amount of leverage you have over the cutting/turning edge bevel. So if you wanted the ski to roll up more to the right, move the boots right. The ski will roll more easily that way and less easily the other way. You can definitely tune your ski setup this way, although I'd put this adjustment in the "advanced" category.

@Luzz very good point. I suppose we could file this under "Misunderstanding" as opposed to "Misconception".

OK @Horton what you're bringing up here points out another big misconception: PERCEPTION...Just because you perceive something one way doesn't necessarily mean that's what's happening, and it definitely doesn't mean someone else will perceive it the same way. I'll use your question above to try and illustrate my point. You focus on staying countered at the end of off side, and that's great if that's what's working for you. But what does that mean? Countered compared to what? I personally try to stay with the rotation of my ski on offside, without getting ahead of it. @Luzz, who is a much better skier than either one of us, says he's not trying to counter and he's trying to stay in line with his ski. So we have 3 somewhat different approaches and we are each probably telling people to do what we are trying to do whenever we coach. But are we really doing what we say? Or is that just how we perceive it... We are all right foot forward and the first 3 videos I pulled up all started at 32off so that makes this comparison very easy: Here's John at offside. My analysis of this is that you are sorta open in the first frame, and by the third frame you are pretty much in line with the ski, or "closed off". It's hard to tell in these 3 frames but this was a very nice smooth turn on video and you ended in a great position. Me...never really "open" per se, and I let my hips get behind me, but that's not the point. The point is in my mind I'm fairly "square" to the course at apex, and I'm in line with the ski at the finish. You can see in reality I'm probably a little too closed off at the start and the result is I lose my inside shoulder a bit at the finish. And then we have Matteo. Now Matteo is a much better skier than either of us, so it's interesting to see that he looks to be more "open" than either one of us. Goes to show that what he may mean by "countered" and what you may mean are not necessarily the same thing. It's all about how we perceive what we're doing. I was too lazy to try and find clearer shots for Matteo, but if you can't tell he's making a much smoother turn than John or me... The point is that you may perceive yourself to be open, but maybe aren't as much as you think. I may perceive myself to be square with the ski, but maybe I'm not. It's more valuable to get video and really watch what we are doing and evaluate, as opposed to going off what we think we're doing.

@swervelake I'm planning to use some clever placement of flow media and feed lines outside of the part to draw the resin flow front down the length of the ski from the tail to the tip. By putting the feed spiral tubing on the sides of the ski I am theoretically only flowing 1/2 the width of the ski. The resin will flow from the sides and meet in the middle. By taking advantage of the fact that the tail is narrower than the tip and by placing the spiral feed lines in a "V" shape on the mold, the resin will meet first in the tail. Then that "meeting" point will move up the ski from the tail to the tip, theoretically trapping no dry spots. Clear as mud?

@SkiRV that would definitely be a novel! And I'm not sure I or anyone else who has spent countless hours learning the intricacies of ski design would want to divulge all that information to the world... :D I agree with @eleeski there is definitely something magical about building your own ski and then taking it to the lake and riding it. I still remember pulling the first ski I ever built from the mold, I was soooo nervous! With proper oversight anyone could build a good ski given that the right equipment is available.

Ok I managed to get a little work done. Thanks to my wax problem that occurred because of the cold temps I had one spot where the gel coat chipped pretty badly at the back of the ski cavity. It's actually pretty easy to fix: I didn't get a good shot before I started but it was the back left edge of the ski where it rounds to the tail. I used masking tape to mask the area and to also act to reshape that area: Then fill the area with more gel coat: Once it's cured I sand away the excess: And voila! Like it never happened So the next part is going to be tricky. Casting the core. I've never done this without the assistance of a press before so we're stepping into the unknown here. I have a plan though and I've consulted @adamhcaldwell who is the master of DIY cores, so hopefully it works out. I'll document it either way ;)

From a feasibility standpoint I think what @skoot1123 and others recommended would make the most sense. There are a lot of tools and additional equipment that go into properly building a ski so even if you had your own mold it would be tough to take it home and use it. You could ride the available skis, decide on the one you like best, then go build it either as is or with recommended modifications, usually flex or rocker changes. Believe me flex and rocker changes make a big enough difference. Goode would do well with a program like that since they have a lot of ski choices and a lake nearby. Radar too possibly?

@Wish @MS thanks just remember than anything I say in the coming weeks is after little sleep and has been poorly thought through. I tried to make a GIF to show how much the ski slips but I think watching this one might make me throw up. The blue line is the path the ski is actually travelling on. You can see why it looks like we take so much more angle than we really do. The ski is slipping (smearing?) a LOT. Again this is not measured from anything, just my approximation of what I think is happening.

One of the biggest misconception is certainly how much angle we really take across the course and the line we take to the ball. We move DOWN the lake much further than we move ACROSS the lake. We're basically racing the boat from ball to ball. You start to wrap your head around that and your entire world changes. I've been up at 3AM every morning with a crying baby so I used my time to throw together a crude representation of the handle and skier's path in the course to try and show this. This is not measured from anything, it's just my idea of what the path should look like. Everything is to scale though and that's a 38off rope. If you are prone to seizures or are easily hypnotized I suggest you look away.

@ozski as far as your questions: When should I pull out for the gates at 32 / 34 / 36 - same place? How wide? Pull out till you're about as wide as the buoys on 2-4. When you pull out will depend on your stance, your ski, whether the boat is up to speed, wind etc. You will need to experiment to find this. When do I turn in? Am I on the front of the ski or the middle? Your goal is to be able to turn in and start progressively pulling from a wide point, timed so that your max pull happens at the 1st whitewash and you make it through the gates. Like before there's no hard and fast rule, it takes some experimenting. Also you want to be waaaaay up over the ball of your front foot on the pull out and the turn in for the gates. Like way up. How far should I pull / lean / stack for? Refer to my previous post. The best skiers in the world pull for an incredibly short amount of time. The better your stance and pull is the shorter you'll be able to pull. How can I improve my body position alignment? Previous Post Is it correct to look at the buoy? or in front of it? Yes there's nothing wring with looking at the buoy to make sure you're going to get around it. But the moment you know your feet will clear it pick your eyes back up. Where is the best place to look? Tons of ways to skin this cat. How long should I hold on with two hands? Practice keeping two hands on the handle AND keeping the your body close to the handle until you reach the buoy line. What is the best practice for handle control at long line? This goes hand in hand with "stack" or position in the pull. The better your position the easier this is. So work on your position. How do know if my ski is setup right? Put it a stock and don't touch it. What are the most common mistakes and remedies? Biggest mistake I see is people NOT really trying new things. If you're a longline skier and you'd like to run 39 someday, you know you are going to have to make wholesale changes to your technique. Why not start right now? Yes some of those changes won't be good but you'll learn from it and become a better skier. Don't get stuck doing the same thing over and over hoping you magically get better. It doesn't work that way.

Sorry @ozski I wasn't trying to be an ass when I posted that pic, life dragged me away from my computer. Allow me to explain... When I started skiing for "real" the summer before college my PB was something at 34mph 15off. By the time I graduated college 4 years later my PB was 5@38off 36mph. And no I didn't have a massive growth spurt in there. I think anyone can see improvememnt jumps like that, you just have to be willing to experiment a LOT and take 1 or 2 or 3 steps backward before moving forward. Also watch a ton of videos of pros and get video of yourself. You MUST get video of yourself. I wish the rope started at 28off. Anything longer will just screw you up for later. @drewski32 is spot on that you're better off shortening the rope to 28 and 32 off and just slowing the boat down. The big difference is that at those line lengths you start to swing up next to the boat, and that makes the rhythm completely different. Many people become the master of 22off but because 28 and 32 are soooo different it takes them years to progress (if they ever do). You're better off starting at the short line lengths and slowing the boat down to 30mph, 28mph, whatever you need to run it. As for the pic I posted, I wanted to point out what @Horton mentioned. I don't like the term "stack" because I think it's confusing to try and line all your body parts up with the ski/rope/etc. Instead get your hips as far forward as you can and get your sternum as high off the water as you can, and then while in that position work on moving forward over the ski and getting AGGRESSIVE in your pull behind the boat. A strong position and an aggressive pull will get you much much further than anything else.

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@ALPJr does Connelly offer a lifetime warranty? That's pretty impressive. Assuming they still make their skis the same way (last time I was in their factory was 2011), there are a few things they do that make their ski more durable than others. First off they use some fiberglass in the layup. I'm not sure what there ideas are behind it but I know that it helps with a few things. First it will help with impacts as fiberglass is not as brittle as carbon fiber. Also the laminate being thicker will drastically reduce chances of the ski breaking via buckling, which is by far the biggest cause of ski breaks. Also they use a different bottom material. Most companies print their graphic on a polyester fabric, then soak that in resin and lay it up with the rest of the ski. There's nothing wrong with that method and it works well. What Connelly does differently though is they actually print the graphic onto a thin sheet of plastic, then they vacuum form it to the shape of the ski. That plastic then goes into the mold before the ski is pressed. So there is basically a protective layer of plastic on the bottom of the ski similar to a snow ski. It all adds a little weight but it's pretty cool how long those skis last.

Ha thanks @skiray I'm glad you're enjoying it. @Horton this may be the one ski on the planet that you can't have for free ;)