gator1

@dlokshin‌ Thanks for the clarity. Does the satelite signal set the 5 hz update limit? If not can we buy ten recievers and clock them to update in series? Or just ignore. You've probably already answered more questions then you'll get profit.

@dlokshin‌ Thanks for explaining this all to us. To be clear, I am a strong supporter and hope your company can make this work. At 50 mph, which most of us reach in the course, you are updating GPS once every 14.7 feet. A lot goes on in our sport in 14.7 feet, and we want(need?) to know most of it. !.5 feet means the difference between a middle of the pack pass and a record breaking pass. Do you really believe you can fill in the 14.7 foot blanks with sensors and an algorithm? On top of the fact that there is error in the gps fix you got 14.7 feet ago?

@dcrhrisman: In the heli video Jim is generating 1.4 gs, and that is just at 28 off. Pretty sure that's a fact. Most I've felt in a car is 0-60 in 3.9, but I agree that felt like a LOT.

The Tesla p85d goes 0-60 in 3.2 sec. That's 0.85 g. Way slower than us. From the test report: Motor Trend's "......high frequency GPS data loggers couldn't keep up.....".

Asked and answered in the post title: "......female ballers.....".

Nah. On careful, Double Bastard Ale fueled reflection, I'm done plugging away on this one. I've got the data I need. It'd be nice to get the same data set on Regina running 39, but that isn't gonna happen. It'd be even nicer to get GPS data real time, but going up to a satellite to ask it where it is in relation to something here on the ground 10 times a second is a long shot if you need to be +/- a foot or so. There's a reason nobody is doing auto drive in the course. Not trying to save anybody's achilles with this deal. No dog in this hunt. Between the heli video, this data, responses to my posts on conservation of angular velocity, the "straight back leg" debate, some "pm" ing with the tech heads on this site,and too many hours of video watching I've debunked (in my own pea sized brain) the harmful teachings that I thought I couldn't understand because I wasn't a gifted athlete. Turns out they were just utter bull shit. "light on the line" for god's sake! "trailing arm pressure", and "open to the boat"/closed to the boat, "COM this" and COM that and on and on. If you doubt the utter bull shit line, go back and read a magazine article on technique from 10 years ago. And I tried to make all that crap work. And the people who wrote it believed it just as earnestly as the people who write it today. And while its kind of fun to get horton so exasperated he gives me Pandas and starts talking about his 45 days on this earth and the laws of physics, its not that fun. Now, if I can get him to bet me a new BOS tshirt against the one everybody dog cussed, then I'd get motivated to prove I'm right. So, anyway, speaking of dogs and hunts its PHEASANT SEASON. Anybody that wants to make a tracker like I described above, I'd be happy to give you a download of my thoughts. But they're probably worth less than what I'd charge you, which is a beer. @Skoot1123‌ if you're down in springfield or out to spokane and want a pull, be sure to call.

Thanks @Skoot1123‌ next step is a pot or a rotary encoder at the pylon with an arm like one of the camera mounts. Simple data logger stores time stamped angle. Mark with beep from ZO. Dump into lookup table does the trig.

I'm out. If you ever get your GPS to work (I'm betting you won't while I'm young enough to care, but if you do) I'll look forward to the results.

@Skoot1123‌ Thanks! Don't want to tell the galactic leader he's wrong if I've got a math error.

@tbrenchley‌ Yes. Relative to the boat, you are moving backwards until you get to the centerline. Just like a pendulum is moving down until it gets to the bottom of its swing.

Replace wake with centerline and you'd be right. Even at 43 mph right before he crosses the cneterline jim's speed parrellel to boat (Vx) is less than boat speed. This is what I love about data: forces us to think about what happens vs what it looks like. That or my math is wrong. @Skoot1123‌ you're one of the tribe.....is my trig right?

@Skoot1123‌ Jim has gotten slowed down to boat speed at the ball. That's good, means he won't take much of a hit. A tenth of a second later, he kicks the tail, pivots the ski. Makes a wall of water. That wall is the evidence of him slowing down. As we've seen on other posts, maybe 2gs of deceleration. That's a lot of slow down. He won't speed up until the rope goes tight. But now the ski is pointing at the boat. No pull on the rope. So he is still slowing down. He's a good skier, so he rips his arms into his core as/after he pivots. Creates a little load on the rope, so he starts to accelerate a little bit. As he feeds his arms out, he gets up to about 30 mph. Finally, about 2/3 from ball to whitewater, his arms are finally straight and the rope is getting rapidly loaded, so rapid acceleration begins. @Horton, look at the video, with the perspective that you won't speed up after the ball until the rope goes tight. You'll see it doesn't get tight until 2/3 to the white water. When I look at that graph I can feel each part of the decal/coast/accel, and to me its right where the graph says it should be. Wouldn't it be cool to see what this chart looked like for Regina or JR at 39.5?

No. Real time with an iPad and an app.

While you guys are waiting for GPS to get a lot better, this is the kind of data we can get real time. In addition we can get position mapped onto the course and acceleration mapped onto the course.

Video protractor shows me rope angle vs time. Trig and calculus in pics does the rest.

Well, in the "28 off from a heli" video I posted, for example, my buddy jim's handle is going 29.52 mph as the tail of his ski clears 2 ball, and 39.667 mph as the nose of his ski touches the near whitewater. And we know position, velocity and and acceleration at every 10th of a second of the pass. Seems to be worthwhile data. For those of you keeping track, he did PB this summer after about 15 years at 34 mph, and earned his lap dance two sets in a row. But I'm not sure he ever collected.

So is Ilse sporting a Dromedary or Bactrian?

About $2k would get you first prototype of a system that would give you handle path position, velocity, and acceleration relative to the course. If you want COM or ski path data that is a tougher deal, but in my opinion handle path is good enough. It'll take us years to figure out what that means, and what it implies for skier form and ideals. The system would be about $200.

@jipster43‌ be sure you check with Mapple on the fogman/T combo. I'm not sure you can mate them. I'm pretty sure the binding stiffness progression goes: two floating plates, single floating plate, single Velcro plate, single clamped plate. I think the big jump in added stiffness is the clamped single plate. Some folks were surprised the Velcro added ANY stiffness whatsoever. @SkiJay‌ it is freaky that you can ruin a skis perf with a binding switch. But very believable based on mechanics. Clamped plate turns it into a big I-beam.

@supersonicus‌ Check thread "holy grail of fin modification". You probably are stepping in something. @MattP‌ I don't have permission to disclose that. But regardless of good or bad reports, I'll post them when I get them.

@SkiJay‌ He just needs a gator tail. Other pros are testing it now.

Allright! snake stories! Rock river Illinois, water mocs. Jumping, uncle butch at the wheel, me in the boat, Gordon in the water. speedos plug (1982). stop the boat, grab the safety pin, lean over the transom start digging at the pitots. Notice the brown carpet on the platform next to my face appears to be moving towards me in a strange sinuous manner. Rear back up, yell snake. Uncle butch has a problem with snakes. Namely, he responds like a frightened child. Butch starts squealing, punches the gas. I tumble from motor cover to platform, butch backs off gas, snake rolls from platform to water, Gordon is pulled towards snake, snake takes a bead on Gordon (mocs are territorial and will come after you). Gordon starts screaming hit it hit it. Ah, good times on the river.

@Horton‌ You left out the only one I care about...What'd you have to do on the Prophecy? And it seems like less load and more angle and speed at the rooster is the goal. So that seems like the wider you are when you can get the line loaded, provided you have pivoted the ski first, and not stood on your back foot, and can handle the load without losing angle or coming back onto the rear foot, the better. That means you can get to the rooster with mainly centripedal force on the rope, since you have already reached "terminal" velocity, the ski can be off edge and you can be up on the front, which all minimize drag and lets you use the speed to glide out before you start slowing down. The only thing I can figure out is some skis/skiers are more able to pivot quickly from wide without getting stuck on the back foot, or getting pulled off the edge, while other combinations of ski/skier are more able to hammer the pull from whitewater to rooster. Maybe like there is a T1 and a T2 for pullers and turners. Maybe there is an optimum pivot/load rate for each ski/skier combo, and the good guys figure that out. While my optimum appears to be more related to whether I had a good crap that morning and what phase the moon is in. I did note that the top end of the big dawg at broho all seem to pivot and load in the blink of an eye.

Those last 3 posts seem contradictory to me.

Meh. In Illinois we keep a .410 in the boat to clear the course before we jump in. And the carcasses keep the snapping turtles occupied while we get our sets.