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Go Back   WakeWorld > >> Wakeboarding Discussion Archives > Archive through April 03, 2009

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Old    joseph johnson (johndoe30o)      Join Date: May 2006       03-27-2009, 11:29 AM Reply   
does anyone know a formula that i can use to find how much air im getting?
Old    Luker (xbones)      Join Date: Mar 2007       03-27-2009, 11:31 AM Reply   
picture x rider / wake jump = height
Old    Bryan (westsiderippa)      Join Date: Dec 2006       03-27-2009, 11:31 AM Reply   
its called a camera
Old    Steve (skidaddy)      Join Date: May 2008       03-27-2009, 11:32 AM Reply   
No formula but video tape yourself. Trail a tube & jump over it for a point of reference. Put a tall person you don't like in the tube if you want a higher point of reference.
Old    Jake (exfuze)      Join Date: Mar 2009       03-27-2009, 1:33 PM Reply   
You can count 'hangtime' using frames on a 30/60/300 frames per second camera. It's being used as a way to classify height.
Old    derek (to_blind)      Join Date: Mar 2007       03-27-2009, 1:38 PM Reply   
Upload
ok, napoleon.
Old    H2O Pro Accessories (h2oproaccessories)      Join Date: Sep 2007       03-27-2009, 2:17 PM Reply   
Classic Derek! I needed a good laugh today.
Old    Andy Nintzel (andy_nintzel)      Join Date: Sep 2004       03-27-2009, 2:34 PM Reply   
Enter Parks Double or nothing so they can count the frames
Old    Jake (exfuze)      Join Date: Mar 2009       03-27-2009, 2:51 PM Reply   
Or get a camera and count your own.
Old    Jay Conrad (pwningjr)      Join Date: Apr 2007       03-27-2009, 2:51 PM Reply   

quote:

Enter Parks Double or nothing so they can count the frames



And then own everybody there.

(Message edited by pwningjr on March 27, 2009)
Old    justinh            03-27-2009, 4:27 PM Reply   
Mount a high speed camera with a range finder 30' up on a pole at the edge of the lake. Find your highest frame and get a reading from your range finder and triangulate the distance between the camera/water level and distance between the pole/rider.

Unless you go higher than 30ft, then you will need a higher point to mount your camera. Actually, you may be able to triangulate from any height. Any Trigonometery experts in the house?

I've never needed all that. I pretty much have an altimeter in my head. When I say I got like 20ft of air, it can't be disputed.

It's Friday, I'm going to the lake this weekend and I am just messing around. But really, I think the trig approach would be your best bet. Like a ski-jump meter on its side.

(Message edited by justinh. on March 27, 2009)

(Message edited by justinh. on March 27, 2009)
Old    Jason Pavik (jasonpav)      Join Date: Dec 2008       03-27-2009, 4:31 PM Reply   
You can probably find it if someone measures the change in angle of the rope from the tower. Do some trig with that and you might find a close height. It probably wouldn't be really accurate though unless you could keep the rope completely straight and tight with the boat
Old    Bill Sloan (bill_sloan)      Join Date: Nov 2007       03-27-2009, 4:38 PM Reply   
Look down.
Old    Austin B (splatman)      Join Date: Jul 2008       03-27-2009, 4:43 PM Reply   
I've found that using a dolphin with a helmet mounted laser is the best method.

The dolphin swims under you in the middle of the wake, and the laser shoots strait up and bounces off the bottom of your board back to a reciever unit also mounted to the dolphins helmet. Then all you have to do is put it into the formula: D2=1/2(X)+(-2.033) and you got your height.

It's foolproof.

PS a note about choice of dolphins. Try to go for the bottlenose, the ones with spots can be a bit moody.
Old    Jason Callen (westsidarider)      Join Date: Feb 2003       03-27-2009, 5:08 PM Reply   
On a serious note there will soon be a product you can buy that measure all kinds of stuff from height of jumps, speed durring cuts, your trajectory, and even records your entire set. cant give any more info out other than that but it was in r&d last year so I would expect it to be released in the near future
Old    Spencer (spinner_x)      Join Date: Jun 2008       03-27-2009, 6:20 PM Reply   
Tape measure.
Old    Rich Dykmans (richd)      Join Date: Oct 2003       03-27-2009, 7:04 PM Reply   
It's like the size of the wave you just rode - just call it yourself, your crew will always tell you it's way less!Upload
Old    Jeremy Byrom (wakerider111)      Join Date: Jul 2006       03-27-2009, 7:37 PM Reply   
or sometimes the crew (a crew whom you highly trust, because their wake skills exceed your own for one) will call it as being MORE than what you would guess, but then there was no way to confirm if it was actually "more" or "less" or "spot on" since there was no video or pics. ;(

pics and video is the way to go, nothing else will satisfy!... or maybe the word of a pro (as in someone featured often in the mags)
Old    Kevin Hoye (wakebrdr38)      Join Date: Sep 2006       03-27-2009, 8:27 PM Reply   
I know I did well judging by the faces in the boat after a double up. If it was trully exceptional someone else will bring it up after the set. The few times I've boosted 15 feet off the double up, someone else brings it up and confirms the height with others in the boat. Then you just have your days where things are clickin and you know you are doing well. Or when your driver said he lost view of you in the mirror or due to the bimini top lol! The old "wherd' he goooo?????"
Old    M-Dizzle (liquidmx)      Join Date: Jun 2005       03-27-2009, 8:34 PM Reply   
Kevin, I prefer the "ohhs" that come from the boat upon immediately hitting the upple dub. Especially if the boat has females who have never seen one get punted before. My bro's GF screamed right as I hit the crest. I had to ask later "was that your screaming I heard when I hit it?".
Old    Kevin Hoye (wakebrdr38)      Join Date: Sep 2006       03-27-2009, 8:46 PM Reply   
totally...its usually the ladies faces that give it away. good times...
Old    Gordie Taylor (wakeparent)      Join Date: Jan 2005       03-27-2009, 8:55 PM Reply   
How would you measure this?
Upload

(Message edited by wakeparent on March 27, 2009)
Old    AJ (ajcsurf)      Join Date: Apr 2007       03-27-2009, 8:55 PM Reply   
Get a good description of how long you are in the air for, the width of the wake, and the angle of your takeoff.

Take your distance, divide it by the time and that will give you your constant velocity vector in the x-direction. Use that value to solve for your Viy (velocity initial in the y-direction) by doing this.... Viy = Vx*Tan(yourangle)

When you get that, its like tossing a ball straight up in the air. You have time, your initial velocity and the value of g (gravity)=9.81m or 32.185ft/s^2
You can find your height by solving the distance it takes to get to a final velocity of Zero (the apex of your flight). The apex is exactly half of your time so take your time, divide it by 2, thats your new time.

so we have this equation:
Yf = Yi + Viy*(t) - 1/2*g*t^2

where Yi=0 (your initial position), Viy your initial velocity, t is your time (your new one), g is gravity in the appropriate units, and t^2 is squaring your t.

Yf is your final position, i.e., your height at the apex of your flight, i.e. the height of the jump.

You could also solve it this way,
Vf^2 = Viy^2 - 2g(Yf-Yi) Vf is zero (velocity at your apex), Yi is zero, solve for Yf.

I would just get a picture because a tenth of a second to ruin your day (show you that you arent getting high at all) or it could make it??
Old    Kevin Hoye (wakebrdr38)      Join Date: Sep 2006       03-27-2009, 9:21 PM Reply   
all that coming from a guy who can boardslide a rail while drinking a beer...why didn't i think of that (the math formula, and the drinking a beer while slidin...)
Old    Kevin Hoye (wakebrdr38)      Join Date: Sep 2006       03-27-2009, 9:30 PM Reply   
could you measure the board in the picture...lets say an inch long. Then see homw many inches to the water...lets say two. Then take the real life legnth of the board. lets call it a 140. multiply 140 times 2. so 280 cm. Which is 110.23622 inches and divide that by 12. Come to just slightly under 9.2 feet. I think this works anyways... someone would need to verify that even if you blew up the picture that the scale would stay the same, but I believe it does since i converted all the numbers to inches in order to calculate.

Oh and the 9.2 feet is to the lowest corner of the board and that looks pretty darn close if you ask me.

(Message edited by wakebrdr38 on March 27, 2009)
Old    Dave (daveronix199)      Join Date: Feb 2009       03-27-2009, 9:57 PM Reply   
When ur in the air count the seconds
Old    schooledrider (rmcronin)      Join Date: Aug 2002       03-28-2009, 6:18 AM Reply   
If you're in the flats, your knees hurt on impact, or you often "roll down the widows" waiting to land, you're getting enough air.
Old    TFD (tommmyd)      Join Date: Jan 2009       03-28-2009, 6:23 AM Reply   
Possibly the funniest thread EVER :-)
Old    Rich Dykmans (richd)      Join Date: Oct 2003       03-28-2009, 8:24 AM Reply   
Measure the size of the rider's eyeballs! Upload


Upload


(photo courtesy of Dave Williams)
Old    Ben Wilcox (benjaminp)      Join Date: Nov 2008       03-28-2009, 9:33 AM Reply   
Just got my new issue of WBM, and there is a product in here that is perfect for you. Its called the Shadowbox, and it mounts to your board between your feed, measures your jump height, distance, and hangtime, your rotation and spin rate, launch angle, g-forces, speed, and board angle. All done with GPS, and its supposed to be the size of a deck of cards. It will be released this summer, check out the website: www.shadowboxlive.com
Old    joseph johnson (johndoe30o)      Join Date: May 2006       03-28-2009, 8:45 PM Reply   
thanks for the help everyone or at least the serious ones,the sarcastic ones are funny though. Im looking for as opposed to just using a picture because im thinking about doing this for a math project.
Old    joseph johnson (johndoe30o)      Join Date: May 2006       03-28-2009, 8:48 PM Reply   
also does anyone know where i can find a freaking dolphin with a freaking laser beam attached to its head in the western north Carolina/ eastern Tennessee area?
Old    Jeremy Byrom (wakerider111)      Join Date: Jul 2006       03-28-2009, 9:17 PM Reply   
^^^??? WHA ???^^^ laser beams? dolphins?
Old    Don Christman (ktm525)      Join Date: Mar 2009       03-28-2009, 9:31 PM Reply   
If have have to ask you didn't go high enough!!!! GO BIG OR GO HOME!!!
Old    Tim (dukeno1)      Join Date: May 2006       03-29-2009, 6:28 AM Reply   
That laser headed dolphin was funny as shyiatt!
Old    Jeremy (wake77)      Join Date: Jan 2009       03-29-2009, 5:11 PM Reply   
All of you trig masters can use this fomula:

Take the sine of your launch angle and multiply that by your velocity in meters per second.

sin (angle) * velocity= your height in vertical direction. Air reistance will have an effect on the result so it won't be 100% accurate.
Old    Jeremy (wake77)      Join Date: Jan 2009       03-29-2009, 5:12 PM Reply   
I apologize for the spelling of my last post

formula

resistance
Old    Jeremy Byrom (wakerider111)      Join Date: Jul 2006       03-29-2009, 5:21 PM Reply   
FOUND IT!

Upload
Upload
Old    Jeremy Byrom (wakerider111)      Join Date: Jul 2006       03-29-2009, 5:22 PM Reply   
Flipper just got 'cuter'...
Old    Roddyrod (wakeslife)      Join Date: Jul 2005       03-29-2009, 8:52 PM Reply   
Nothing like the feeling of getting booted off a doubleup!

I need to ride! (it snowed today)
Old    Jason Callen (westsidarider)      Join Date: Feb 2003       03-30-2009, 2:12 PM Reply   
Ben- that's good news that the shadow box is being released finally. I did some r&d work with them last spring. Its a pretty cool device. We had a laptop on board and I was able to come back in after each set and watch a replay of my boards movements on the screne. Its really cool device
Old    Craig Cox (wakedoctor)      Join Date: Dec 2004       03-30-2009, 2:17 PM Reply   
Why not just use the angle of you line?
Old    Gerald (sloshake)      Join Date: Mar 2003       03-30-2009, 2:24 PM Reply   
If you can measure the time in the air really accurately, then you can do this. And yes, this does ignore any effect having a tower as opposed to putting the line on at the bottom would have on you.

I dont remember the exact physics formula, but gravity is 9.8 m/s/s. If you can figure out how long you're in the air, exactly half that time is going up, half is going down. Then you've got the acceleration and the time, figuring out the distance is easy.

As for the pics above, the exact heighth would be somewhere between huge and insane.
Old    John Anderson (fly135)      Join Date: Jun 2004       03-30-2009, 2:27 PM Reply   
Yf = Yi + Viy*(t) - 1/2*g*t^2

Just remember... The angle of the dangle is inversely proportional to the size of the rise.
Old    AJ (ajcsurf)      Join Date: Apr 2007       03-30-2009, 3:24 PM Reply   
Refer to my post above about regular kinematics....

And Craig, using the angle of your line would only be beneficial to figure out the length of your jump. Take your angle and take off, angle and landing, and voila, an isosceles triangle. Since you know your rope length, (the hypotenuse) you can solve for the length across by some trig identities. You would have to bust out the protractor and square it up your tower and get the angle of your line. That would be the angle at the top (between your equal lengths of your isosceles). Divide that by two, and you have two identical right triangles. Solve for the smallest side, multiply it by two and thats your length across the wake.
Old    Craig Cox (wakedoctor)      Join Date: Dec 2004       03-30-2009, 4:24 PM Reply   
Im not meaning the angle from side to side, but say he had a picture taken from the side with the rider at his highest point. Now find the angle of the rope, horizontal would equal 0. Find your rope length..... You are a grad student with trig knowledge so you should see where I am trying to go with this. He would still need to know the distance from the tow point to the water and from his hand to the bottom of the board, but this would get him in the ball park range.
Old    AJ (ajcsurf)      Join Date: Apr 2007       03-31-2009, 3:14 PM Reply   
ahhh....angle above the horizontal relative to the tower....yeah. That would work. Finding the height of the tower while the boat is moving might be a little tough..... That would probably be the easiest way to do it.....

keep in mind, a difference of a degree makes a big difference. With an 80ft rope, the difference between a 4degree and 5 degree angle is 5.56ft and 6.97ft respectively. It might be hard to get an accurate angle.
Old    Jeremy (wake77)      Join Date: Jan 2009       03-31-2009, 8:46 PM Reply   
Not to get too involved into the physics of the question. But using the Yf formula that John suggested must include air resistance and the launch angle from leaving the wake. Without the angle it would be impossible to find max height only max distance in the x-direction. It will have an effect so when using the formula, you will need to calculate the friction due to air resistance. And another factor to add to the complication is that a radar gun or similiar device would be necessary as you would need the speed of the rider, not simply the boat speed.


I saw at the beginning the kid wanted to use this as a school project. So for a school project I guess a lot rides on what kind of class you are submitting the project. Calculating air resistance into the max velocity formula is generally a calculus based college physics class. But otherwise, in this month's mag, I saw an advertisement for a device that mounts to your board and give you your height.
Old    wakemark (waketac)      Join Date: Apr 2002       04-01-2009, 12:36 AM Reply   
Use this http://shadowboxlive.com/
Old    Loren (helix_rider)      Join Date: Mar 2003       04-01-2009, 9:27 AM Reply   
Good call Wakemark...I was just coming to post the site. At first I thought the thing was an April Fool's joke...
Old    Mike K (mike2001)      Join Date: Feb 2008       04-01-2009, 9:43 AM Reply   
Just keep jumping over progressively taller friends, till you don't clear one. Measure the friend of the previous jump to get your max height.
Old    Boardingitup.com (wakeboard19)      Join Date: Apr 2005       04-01-2009, 1:37 PM Reply   
You can see the press release on here.
http://www.boardingitup.com/shadow_box.htm

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