DefectiveDave

Great interview, thanks Corey and Marcus!

In my mind, a beginner would be anyone skiing below their maximum boat speed at 15-off or long-line. My reason for recommending a mid-level ski is because they ride a bit higher in the water and the tail sinks less at low speeds. Most people at the beginner level tend to be slower at most points throughout the course, which allows the tail to sink, which then in-turn necessitates tail-riding. In my mind, anything that keeps a beginner skier in a more neutral position is a positive. In my somewhat limited experience the mid-level skis are also smoother and more forgiving. I've also heard that many are very serviceable into shorter line lengths (up to maybe 35-off). I just think they are a better, and more affordable, platform on which to learn the sport. In the end, while I think that a beginner might learn a little faster on an intermediate ski, I have no direct proof. I think a motivated beginner will make great progress no matter what ski they choose. However, I'm fairly confident that they will be more consistent and have more fun out on the water with a mid-level ski.

Gotta go with Joel. I would be stoked for him, but hearing that news wouldn't surprise me even a little.

That's fantastic, I'm glad he finally got it. Here's to many more!

@david_ski, A smart phone mount would definitely be possible. However, as you have suspected, you will probably need to add a little bit of extra mass in order to bring the natural frequency down. No Diff. Eq. is necessary, just use the transmissibility envelope for zero damping here: https://upload.wikimedia.org/wikipedia/commons/thumb/0/07/Resonance.PNG/1920px-Resonance.PNG Also, you can approximate the natural frequency using the relationship here: https://en.wikipedia.org/wiki/Fundamental_frequency Just be aware that the natural frequency equation in the above wikipedia page gives you the frequency in Hz, so make sure you don't use radians for your target frequency in the transmissibility envelope. Good luck!

@david_ski, As @Waternut said, the JVC camcorders probably get you 70-80% the way there (I've tried sony, canon, and panasonic with really ugly results due to pylon vibration). In fact, in his video it looks like it is working really well. I might try the camcorder first and see if the quality is acceptable before making an isolator. It might be that my pylon has more vibration than normal, but I was still seeing some significant vibration even with the JVC until I added the isolator. Here are some pictures of what I built for reference, it is very basic. - 3/16" wire rope is used to isolate the top platform from the bottom where it is attached to the wakeye. - Blocks at the back stabilize the camera. - A go-pro mount at the bottom is what is used to attach the wakeye. I designed it such that it reduces the transmissibility of anything above about 8 Hz when a 300 gram camcorder is attached to the top plate. Otherwise the wire ropes started getting too long and the tracking would start to lag behind the skier. My final wire rope lengths were 3-inches at each corner. If you want to use different wire ropes, a camera of a different weight, or isolate for different frequencies then you'll need to make some adjustments. My design only took 3 steps: 1) Identify the maximum shear stiffness in a lateral direction. This turned out to be very linear in my measurements and corresponded to the starboard-port and bow-stern directions when the camera is facing directly behind the boat. 2) Determine total mass of top plate. Use this and the stiffness to determine your approximate natural frequency. 3) Use the transmissibility relationship (https://en.wikipedia.org/wiki/Damping) to ensure that you isolate for anything above a given frequency to below a given transmissibility threshold. Assume the damping coefficient is 0 and I suggest trying to reduce transmissibility of any vibrations above 10 Hz, because this is the treshold above which the image stabilization methods on most cameras stop working effectively. Good luck!

Wakeye with a custom built isolator platform. I use a JVC camcorder (GZ-HM650BUS I think) with image stabilization that works well at higher frequencies in case the isolator platform misses something. I think it works pretty well, here's a sample video:

Holy crap. I'm not sure how the rules work in this case, but please tell me the guy at 25 seconds at least got credit for getting back to centerline.

@Horton, Haha, I do what I can. Skiing as really complex, unless I consider spherical skiers in a vacuum I can't draw meaningful conclusions. I just try to simplify things as much as possible and then understand and re-complicate them using physics/bio-mechanics. I then attempt to apply what I've learned on the water. This has worked approximately 0% of the time so far, but it's fun! I have a dream that I will one day arrive at a physics-based waterskiing technique that is moderately useful (or at least not useless) on the water.

@Horton, I think I totally agree with you here, but let me expound a bit. My thought is that any rotation which opens you to the boat is bio-mechanically decreasing the "strength" of your position, but that it may be beneficial to rotate open in certain scenarios. I'm not really considering hip and upper body rotation separately because I feel that one must follow the other to a great extent. Maybe I would go a bit further and say that everything must follow the relative rotation of the ski with a great degree of correlation. For example, someone traveling 50 degrees across course cannot be as open as someone traveling 30 degrees across course. However, physically the ski will point (largely) in the direction of travel while the shoulders (with near equal load though each arm) will tend to want to point in the direction of the pylon but will be limited by each skier's flexibility. From this constrained position, rotating open to the boat will increase rear-arm tension and pull my COM forward, but it will also decrease the moment on the ski which will cause the skier to loose angle. Likewise, if I close myself to the boat at this point in time I will loose a little tension in the rope and shift some tension (whether we feel it or not) to my leading arm; my COM will most likely fall back a little bit but the moment on the ski will increase and give me a little more angle. So my final thoughts there are: Open-to-boat: decreases angle, decreases load, shifts weight forward Close-to-boat: increase angle, increases load, shifts weight back To me it would really be a balancing act in body rotation in order to maintain balance and strength on the ski and I don't think any top-level skiers consciously think about such things (maybe they act on them somewhere in their lizard brain though). In practice, I don't think it's even possible to manipulate these dynamics in any meaningful way for mere mortals. Once you are under load it is very difficult to fight the boat in order to make such adjustments. To a large extent you are loosing to the boat as soon as it picks you up, it's just a matter of how long you can hold out. If you're really good you can keep the boat in check until you get free of the boat going into the turn. However, unless you are at an easy line length (for oneself) you will not be able to make significant adjustments and hence performance to a large degree is determine by your initial body position. Thus, and here's where I finally get to the point and agree with you, I believe the best approach is to be in a natural, balanced, and strong position when the boat picks you up. I don't think that trying to close or open oneself to the boat is the way to accomplish that position.

Camaro is far and away the best wetsuit I have ever owned. My 2mm is comfortable down to 55F water, maybe more, beyond that my feet get really cold. It has proven to be a little more high maintenance than I would like, but totally worth it. In the fall and winter it is my favorite piece of equipment. Also, it's really comfortable and non-restricting. Almost like a second skin.

@Kelvin, That matches up with what I saw in the clip I just posted above. It looks like we simul-posted so I didn't see your post first.

@bbirlew and @Horton, Thanks guys, so it looks like we're waiting on the 2nd generation hardware. Hopefully the Xensr doesn't turn out to be vaporware, but I did at least find this recent video (from 10/16/2015) where they are claiming to release next month: http://www.wltx.com/video/3977619349001/1/CES-2015---Xensr-Quickie They're also claiming significantly higher GPS temporal resolution (40-100 Hz depending on where you look). Seems like it is worth waiting on the Xensr at this point given that winter is fast approaching. @bbirlew, I have been keeping up with the RAT-IPA-Swerve development and it's exciting stuff. I'll end up picking up the Xensr eventually, in which case I will be happy to provide data if it helps you guys out. I'm hoping that it catches on and we can start building a useful database in addition to having the real-time analysis capability. Once I get the Xensr (or maybe another product emerges) I will be trying to attach it to as many skiers as possible. What good is a single data point? :-D

Has anyone been using this device in the 9 months since we last talked about it? I thought at the time that @Horton's original videos showed great promise, even if there were just a bit out of sync. Did it prove too finicky or inaccurate maybe? Even going back to them now I feel there's a lot that I personally can learn from them and I'm debating whether or not to get one myself so I can make comparisons. The 5Hz GPS refresh rate doesn't bother me like it does others as I think the average (maybe interpolated) performance of 0.2 seconds is plenty enough to draw some general conclusions. It also provides a very relate-able, objective, granular, and differentiable quantitative metric (velocity) which can be used at all points in the course. While RAT-IPA provides more temporally resolved, and probably more accurate, data at the moment, this is relatively cheap and best of all COTS. It also has the benefit of providing "good" data with a slack line. The only thing holding me back is the lack of other comparative data by others. @Horton is a good start, but I'd love to see data from some of the other great skiers on BoS. LFF vs. RFF, one-handed vs two-handed gates, radar vs. d3 vs. radar vs. HO vs. denali vs. connelly, the list goes on. If the tech is as good as it appears in Horton's videos, then these comparisons could already be meaningful even if the temporal resolution isn't quite there yet. I would get the ball rolling, but my immediate group of skiers (myself included) would only provide the low-end of the performance/ability spectrum. I doubt that would be useful to anyone other than ourselves. Another option I've been considering is buying one and shipping it around to skiers who would be interested in generating the baseline data.

Whatever you end up doing ,the key is going to be consistency more than anything else. If you decide to get in shape 1 month before ski season, you will be disappointed, but if you work out all winter you will be pleasantly surprised. I would recommend some form of compound full body lifting exercises like deadlifts, squats, pull-ups, and benchpress in addition to dynamic activities which require core work. Play basketball, go biking, or pick up swimming (indoors of course). You might as well have fun getting in shape!

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This really hits on something I've been pondering lately as well, especially with respect to my gates. I've reached some conclusions based on the comments of @Wish and others. However, I'm not the greatest skier (practice PB of 1 at 32 off) and this is just my current understanding (which seems to evolve significantly over time). It seems to me that being open to the boat should be more of an effect than an action, but it can be used to positive effects in certain situations. Opening to the boat has some benefits during the loading phase which appear to be: - Allows COM to shift forward - Lowers the tip of the ski - Decreases "load" However, opening to the boat has some drawbacks as well: - Lessens your leverage (weakens your position) - Reduces your degrees of freedom (just try closing yourself back off to the boat) So like everything it ends up being a matter of balance. If you open too much you end up in a weak position, or if you open at the wrong time then you are not able to open up later when you need to move your COM forward or get the tip down into the wakes. However, if you don't open up at all then you might end up too far back on the ski with too much load. I think there is a wide range of correct techniques here, so I will provide what I think are two extremes. The first is Andy Mapple, who opens a little bit but only under extreme load. Generally he stays closed to the boat until he has to open a little bit in order to decrease the load and get the tip of the ski down. It seems to be a bit of a brute force approach, but it obviously worked extremely well for him and he was athletic enough to make it happen. I think this is very apparent in the 28 off gate shot in this video: The other extreme I believe is Nate Smith. He is very smooth and controlled into his gates and has a more gradual transition to an open stance. He is never fully open to the boat, but he is more open than Andy Mapple. My thought is that he is probably optimizing his core rotation to better keep his COM forward and the ski tip down. You can only open so much, so he doesn't do it all at once, rather he uses his rotational degree of freedom as needed in response to the boat and the result is a very fast and smooth gate shot. I think this is pretty apparent in this video: So to me the common link in this case is that they both fight being open somewhat, they don't just quickly do it in order to get their COM forward and tip down. They do it in response to a loads from the boat. Mapple appears to fight it the whole way and only opens as much as the boat forces him, while Smith seems to open gradually in order to decrease load as needed while still getting a ton of angle. Whatever they are doing, they are doing it differently and both approaches work very well, but it's not as easy as simply opening oneself to the boat. My personal goal right now (once I get into the course) is to brute force it like Andy and fight being open as best as I can going into the wakes and only open when the boat forces me to in order to get my COM forward. I don't have his strength or ability, but this should make me strongest at the wakes in order to keep my outbound, I'm hoping. Anyhoo, that's just my 2 cents.

@matthewbrown and @Marco, You're both absolutely correct. Keeping it simple is going to have to be my mantra going forward, haha. I've got enough to work on the rest of the season. On Friday, even though it was just the gate, I was having a lot of trouble keeping everything in my head. By focusing on everything, it's almost like I'm not able to focus on anything at all. Still, I'm getting an idea what works during the gate and now I know what to look for myself when (or if) I make any further videos. Right now it's just time to practice, practice, practice on thing at a time. Thanks guys!

Hey all, looks like the consensus is that I'm not keeping my arms straight enough, which is a distinct possibility. So that's something I'll need to add to the already very long "fix it" list. In the meantime I can probably add more intense and isolated bicep work to try to keep the soreness to a minimum. Thanks Ballers!

@Chef23 and @ToddL, I ski on Lake Davidson (kind of a part of Lake Norman) and live in Mooresville, NC. You're absolutely right, and so was @ToddL. I was digging deeper last night comparing videos of myself and the GOAT. I did some timing tests and realized that from the start of my pullout to passing through the gates was about 6.5 seconds @ 32 off. When I watched the videos of Mapple, his timing for 34.2 MPH @ 32 off from the pullout to the gates was about 5.5 seconds. This also lined up well with what @ToddL was saying about the maximum glide time being about 3 seconds. Nate the Great's timing from pullout to the gate was even less at around 5.25 seconds, but that's at 32off, 36 MPH with more drag. Just for fun I backed these numbers out to see where they were in relation to the 55's. Skier Distance from Gates Mapple: 50.16 ft/s * 5.50 seconds = 275.88 ft Nate: 52.80 ft/s * 5.25 seconds = 277.20 ft Me: 50.16 ft/s * 6.50 seconds = 326.04 ft Front of Boat Distance from Pre-Gates Mapple: 275.88 -43' of rope - 10 ft of boat - 55m *3.281 ft/m = 42.4 ft Nate: 277.20 -43' of rope - 10 ft of boat - 55m *3.281 ft/m = 43.7 ft Me: 326.04 -43' of rope - 10 ft of boat - 55m *3.281 ft/m = 92.6 ft From my perspective behind the boat I was sure I was only about 40 ft from the pre-gates before I pulled out, but the numbers don't lie. I trust the math more than my own subjective assessment of distance. I got the chance to ski today (but no video) and decided to delay my pullout by 1 alligator from where I normally would to put me near where Mapple was. I only got 4 shots at it before I had to call it a day (body just wasn't ready to be on the water again), but there was potential. I was definitely drifting in significantly less, but I'll have to develop a better sense of timing with the delayed pullout. I'll take more video the next chance I get to combine the above concepts with a delayed gate pullout. So now there are 3 things: 1) Weight Forward, hips at 10 o'clock 2) Initiate turn with intensity by bringing hips from 10-2 3) Pull out later for gates Thanks for the help everyone. I know it seems like I'm running in circles, but I feel like I'm learning a lot right now and making progress!

@Texas6, @andjules, @Marco, It's not really tendinitis. It feels like delayed onset muscle soreness right where the bicep and forarm meet the elbow joint. The soreness appears to be in the muscles themselves. However, the soreness of the muscles is localized close to the joint. So it might be where the tendon meets the muscle. It generally clears up in a couple of days, but it makes it difficult to ski for at least a few days if I get the chance. Today I actually had a rare opportunity to ski for the second time in 3 days, but by my 4th pass I was barely able to get up from my deep-water start due to the soreness/exhaustion in those muscles (I'm a skinny guy at around 160 lbs). @tc, So you're saying it's a bicep activation thing? I can definitely give them a shot, couldn't hurt.

I'm talking about the soreness which occurs after you have skied. It is generally most obvious when you try to straighten your arms or flex your bicep the day after skiing. I know this is a really common soreness which generally passes as we ski more, but right now I'm struggling with it every time after I ski due to lack of time on the water. Does anyone know the root cause? I want to add some work at the gym to keep this from happening the next time I hit the water. Currently my gym work is purely focused on skiing and consists of deadlifts, squats, planks, pull-ups, and deadhangs (for hand strength). It seems to me it's either from bicep activation during the pre-turn or due to load on the arms during the pull. Thanks!

@Drago, I tend to way overthink everything, haha. When I ski a lot I can just relax and ski, but when my time on the water is so limited the mind wanders. Luckily none of this stuff is going through my head as I approach the gate or I would be screwed. I just pick something to try (generally one thing, two things max) and then go for it. I can evaluate the results after the fact.

Just don't strap so much weight that it sinks. That would suck.

Thanks for the comments so far guys. I think I just made another observation which may be relevant. I mentioned earlier in this thread that I tried to keep the rope tight during the glide, and that much is true. However, looking at that video I can't help but notice there is some significant slack in the rope during the glide. It's not much, but it's enough to decrease or even eliminate the load of the boat as we match speeds. I generally turn in when I "feel" that the time is right, which I gauge based on when the boat starts loading the handle. This in turn affects the habits that I build such as when I pull out and the duration/intensity of that pull out. Could it be that I have too much slack in the rope during my glide which is throwing off my timing at the gates? If you look at the video, it really looks like I start my turn-in when the rope tightens every single time. I currently feel that I keep around 5lbs of tension in the rope during the glide, but maybe trying to go for 15-20lbs might be helpful?