Boy Dies on Verrückt at Schlitterbahn Kansas City

Thursday, August 11, 2016 1:57 PM

I'm not sure hitting hard plexiglass would have a desirable outcome, either.

Thursday, August 11, 2016 2:22 PM

Sure, but it's not going to decapitate someone. Have you ever been on a tube slide where you catch some air? The "straight drop" one at Waldameer launches you forward so far forward when you break over that I've hit my face on the top part.

I'm sure you'd get hurt if you flew into that, but I don't think he was "launched" into it so much as one of the metal poles caught his neck and he kept going forward.

Thursday, August 11, 2016 3:14 PM

You're going to end up in the hospital regardless of the surface if you hit it face first going 65 mph. Just more reason that this ride should've never been built.

Last edited by PhantomTails, Thursday, August 11, 2016 3:14 PM
Thursday, August 11, 2016 3:59 PM

Ok...let me clarify. The 46 year old "me" said "holy crap". The 20 year old me would have been all over that airtime slide.

Thursday, August 11, 2016 7:35 PM

Note to self: Don't post long format from iOS.

With that out of the way...

There has been a lot of discussion about the restraints on Verrückt and the impact of their failure. Personally, I don't think it makes a bit of difference.

Remember, we are talking about a water slide here. The rafts on Verrückt are NOT fixed to the channel, and for this reason it is theoretically impossible for a rider to get any airtime on the ride, at least as we understand it as coaster nuts. A rider in an inertial reference frame will not experience -Gz (upward) forces on the ride. There is no mechanism in place which will create a -Gz force. When the raft reaches the top of the second hill, it will attempt to follow a ballistic path, and if the slide flume is at or above that ballistic path, the raft will follow the flume. If the flume dips below the raft's ballistic path, the raft will go airborne.

But the riders will not. The riders are also following a ballistic path, with their initial velocity determined by the boat. This means that the ballistic path followed but the riders should be substantially identical to the ballistic path that the boat would follow if the slide were not there. This suggests that the reasoning behind putting the belts in the raft probably had little or nothing to do with the possibility of a rider being ejected from the raft during the ride. Okay, because of variations in the locations of the centers of mass, and the rebound effect of muscles and inflated raft parts it might be possible for the rider to lift very slightly. But he's not going to be lifted out of his seat in any substantial way, and any insubstantial lift isn't going to be dramatically effected by the presence or absence of a safety belt.

I suggest that the belt is more of a positioning aid than a restraint. While the ride won't produce a significant -Gz force, it may generate a substantial -Gx (forward) force when the raft gets to the bottom of the first drop and starts up the second hill. That is, the raft will slow substantially while the rider tends to keep going. The lap belt may serve to keep the rider's butt from sliding forward off the seat. Meanwhile, the shoulder strap serves not so much to restrain the rider against ride forces, but to discourage the rider from leaning forward during the drop, in a posture that could cause him to smash his face and head into the rider ahead. The critical moment for this would be in the dip between the two hills, so if the strap happens to break away at that point, it really makes very little difference to the safety of the ride: it lasted just long enough to keep the rider upright during that portion of the ride where remaining upright was critical. That the restraints on the ride are not very effective is not really an issue because the restraints on the ride are not all that important.

At this point, I'd like to emphasize an important point: I have never ridden Verrückt, I haven't studied it in great detail, and I have never even been to KCKS, let alone to Schlitterbahn. So everything I suggest here is just as much conjecture and speculation as everything else you've read on the subject.

But I don't think the restraint is of any significant importance to the incident. My suspicion is that for whatever reason, the raft probably became airborne, and in that process the young victim was not lifted from the raft, but rather lifted *with* the raft into a position where he became entangled with the netting structure and was subsequently yanked out of the raft by that entanglement.

We shall see what the investigation reveals.

--Dave Althoff, Jr.

Thursday, August 11, 2016 9:44 PM

Safe to say they remove this Slide and we never see anything built like it again!

Thursday, August 11, 2016 10:33 PM

I also am of the camp that the raft went airborne thus allowing the boys neck to catch the metal netting support. I think Dave's logic seems correct and am wondering if a gust of wind somehow forced the boat up more than had previously occurred, combined with a unique weighting in the boat. What I am very curious to see is if the park was either aware of any "near miss" incidents, or if they did any sort of scientific testing on how close to the slide to place the netting (somewhat similar to the clearance envelope that coaster designers use). The only way that I foresee this ride continuing to operate is with a removal of the second hill.

Regardless, a 10 year old lost his life on a day that was meant to be fun. I shudder thinking about how horribly things went wrong for him. My thoughts and prayers for all those impacted by this tragedy.

Thursday, August 11, 2016 11:48 PM

For you guys thinking the boat went up into the netting. It would destroy the seats as the headrests on Verrückt are high. Here's a website link showing the picture showing the headrests. The 10 year old kid would be well below the top of the headrests. The seats are made of hard rubber foam attached to a floorboard holding all 3 seats which is chained to the boat via carabiner clip. So I don't how a boat would go airborne into the nets and eject the kid.

I have ridden Verrückt at least 40 times. I have had all sorts of experiences with the ride from airborne boats to a crawl over the top and the occasional velcro strap issue. (I always tug it before I leave to make sure it doesn't fly off and just in case I hold on to the straps as instructed.)

Thursday, August 11, 2016 11:58 PM

Maybe it did destroy the kid's seat as well? We have no idea what happened to the boat. Regardless, if the kid was sitting in the front and the boat went airborne, his head is still going to hit the railing before the back of his seat does.

Last edited by PhantomTails, Thursday, August 11, 2016 11:58 PM
Friday, August 12, 2016 12:31 AM

Agreed that there wouldn't appear to be any mechanism that could launch a rider from the raft under normal operation; the rider would at minimum only approach zero-g (but not attain it) at the top of the second hill on a typical run. And I also agree that wet rides also tend to count on both a rider's choice and ability to follow the rules in order to avoid injury, more so than on dry rides.

That said, I haven't found a good explanation as to what is used to slow the raft at the bottom of the first drop. It appears to count on water blasters to make sure the raft crests the second hill, so the speed from the first drop is scrubbed off prior to the blasters by some mechanism. Is there a possibility that this changed/failed and allowed the raft to retain it's speed into the second hill? This would be the only way the raft would leave the flume.

Also, not having ridden Verruckt, I'm not familiar with the pacing of the ride, but is it possible that one could take the first big plunge and then after bottoming out try to stand up and 'surf' crest of the second hill? I know most people would ask, 'Why?' But this was a 10 year old, and I've seen adults try it riding PTCs with one-click on their lap bar. Unfortunate things have happened as a result of that as well. If that is the case, maybe the failure of the restraint was that it was removable by the rider during the ride. With two riders in the raft behind the boy, they might be able to answer if this was what occurred.

Any way you cut it, this is a tragedy for all involved. Prayers for all of the families all around.

Friday, August 12, 2016 12:38 AM

There is a water slide at DelGrosso's that has a small airtime hill called Gravity Groove. I've never seen anyone get any real air on it though. This is the only video I could find of the ride.

Friday, August 12, 2016 1:21 AM

Mister Halo said:
...That said, I haven't found a good explanation as to what is used to slow the raft at the bottom of the first drop. It appears to count on water blasters to make sure the raft crests the second hill, so the speed from the first drop is scrubbed off prior to the blasters by some mechanism. Is there a possibility that this changed/failed and allowed the raft to retain it's speed into the second hill? This would be the only way the raft would leave the flume.(...)

Fluids do not perform the way you might expect them to.

Take a structure like Verrückt, and roll a bowling ball down the drop. That bowling ball will roll down the long drop, and at the bottom it will keep rolling and go on up the other side. It will then roll over the top if it has enough momentum; if it has too much momentum it will fly over the top of the second hill. This is the kind of behavior we expect from stuff going up and down ramps. Roller coasters, Hot Wheels cars, bowling balls, even sliding objects all behave in more or less this same way.

Now take a gallon of water and pour it down the slide. It won't run up the second hill. It will roll down the first drop and form a pool at the bottom. Someone who knows a whole lot more about fluids than I do can explain why this is, but with a few simple experiments you can see that this is the case. Even if the slide is designed to drain the water off at the bottom (and I'm fairly certain it is), I can see the boat getting considerable braking action from that pooling action at the bottom of the drop. Remember also that the boat is sliding down the chute, which means that the resistive force it experiences is going to be proportional to the weight of the boat.

Another issue to consider is the water jet system used to propel the boat to the top of the second hill. The amount of force needed to overcome gravity and get the boat to the top of the second hill is also proportional to the mass of the boat. Given that there is a relatively narrow window of allowable weights for the boat, if the boat is significantly underweight, the jets might actually push it too fast over the crest of the second hill, which in turn could cause it to go airborne over the top.

--Dave Althoff, Jr.

Friday, August 12, 2016 2:43 AM

Fluid dynamics is indeed a complex and non-intuitive discipline of physics. Verruckt was designed to use its principles for both lubrication going down the hills as well as hydrodynamic braking of some sort (at the end if not at the bottom of the first hill as well). The bottom of the first hill would have to be constantly drained or the raft would be slowed significantly by entering the standing water that would accumulate at the bottom. Looking at the pictures and videos of Verruckt, I can't tell if the black patches going up the second hill are just drains, or some sort of raised braking material to both slow the raft as well as give it some stability to keeping if from squirming around in the flume, or a combination of both. The large black patch at the bottom of the first drop definitely looks like it is there for braking as water runs across it rather than draining through it, and on-ride videos show riders heads jerking as the raft reaches this patch. I can't imagine how that sort of braking system could fail, but there is just too much we don't know about the whole setup to do more than speculate at this point.

It is interesting to hear from experienced riders that there is a pretty good range of velocities that the rafts crest the second hill with. But something pretty extreme would have had to happen to propel the whole raft (or far less likely, one rider) into the netting.

By the way, water won't run up the second hill because it can lose energy internally (something a solid isn't very good at) through turbulence and viscosity, as well as to it's container (dependent on boundary conditions), but mainly in this case because it is free for every molecule to take it's own path of least resistance and spread out beyond the sides of the flume.

Friday, August 12, 2016 7:23 AM

With the Velcro, the restraints can be removed by the rider which could be a good thing, see Shot the Rapids.

Friday, August 12, 2016 8:29 AM

This is true. And it also puts a good portion of responsibility back in the court of the rider's choice to follow the rules. Corporate lawyers for a park chain would have likely have pushed back hard before having something like this built. There likely would have at least been an age restriction (even higher than the one proposed) along with the height restriction.

Friday, August 12, 2016 9:17 AM

I agree with Rideman's and Halo's discussion of the physics of the raft and riders. However, you can't discount the importance of the restraint. The most unpredictable aspect in all of this is rider response and behavior. Restraints are needed for rider positioning for weight distribution, but also serves to keep the riders in the raft through the changes in g forces, and to prevent riders from kneeling, standing, etc.

What we know right now is that 1. the boy was separate from the raft at the end of the ride, and 2. there were several reports of malfunctioning restraints on the ride. That would lead me to believe that the boy may have been separated from the raft(either accidentally or willfully) prior to the injury. On a ride like this, it seems to me that once you became separated from the raft, all the physics of the raft weight, rider positioning, etc. are null and you really have no idea what might result.

Friday, August 12, 2016 9:37 AM

I have a question, and maybe Dave or someone else can answer this, but what is the logic of putting the lightest person in the front of the boat? Wouldn't the boat behave more predictably if the heavier people were placed in the front and back? I think the reports have said that he was in the front seat and I am just questioning why that is.

Friday, August 12, 2016 11:55 AM

Two reasons that you would want the weight in the back are:

A) If the the raft's weight is nose heavy, and the raft does become airborne for some strange reason, there is a greater likelihood it will over-rotate going over a crest. Keeping the center of mass just back of center will keep the front end up instead of dropping down the hill first.

2) In a braking pool, you wouldn't want a lot of weight in the front, causing the nose to dig in. This is the same reason boats that 'come up on plane' keep the weight toward the back.

The could be more reasons as well.

Friday, August 12, 2016 7:16 PM

^ah, thanks Mr. Halo. I forget about the fluid dynamics aspect of this and wasn't completely thinking about the pool of water at the bottom (and Dave's explanation of water not rolling up a hill like a bowling ball).

Friday, August 12, 2016 10:45 PM

Probably unrelated, but the new Massiv water coaster at Schlitterbahn Galveston has high sides instead of the traditional netting that NBGS used to put on its slides (and on Verrukt). As I mentioned earlier in the thread, this ride was built by Whitewater as NBGS sold off its patents a while back. It's probably just a coincidence, but it makes you wonder if Whitewater had a reason for the new design. You'd think that all the additional slide pieces would be more expensive than steel hoops and netting.


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