Poll – Tower vs. No Tower

[d-dub]

I've been wakeboarding for a long time, and ever since the advent of the extended pylon, and later the tower, there has been a lot of argument over how much they really help in getting more air. So being an engineer, I finally decided to try to crunch some numbers. It turns out to be a pretty complex thing to calculate, but I got some rough results, and I am still in the process of refining my analysis. Before I post my results, I thought it would be interesting to run an informal poll to see what the general consensus is out there about how much help towers and extended pylons give for getting more air. To keep the format consistant, give your opinion based on a percent increase in height. For example, if you don't think they make you go any higher, you would say you get 0% higher, or if you think they make you go twice as high, you would say you get 100% higher. If you also want to add any comments about your opinion on the effectiveness of towers versus extended pylons, which was another big debate when extended pylons were still a popular alternative, it would be interesting to compare those results too. Also, if there is anyone else out there who would like to run some numbers, it would be good to get some independent checks of my calcs to make sure I am not way off base. I'll post my results sometime next week to give everyone a chance to post and let the debate to heat up a little.

D-Dub

[03Belmont]

its not all in the tower.. its in form, wakesize, pop etc.

[Ctipping]

I worked this all out in physics today. The tower will slow down the curve of your airtime, but the curve shape will stay the same. you will get the same height, it will just take more time to get from takeoff to landing.

[Jim M]

[irish_rider]

is a tower better than an extended pylon the rider cannot pull the boat as much.

a tower/high pylon is better because when you jump across the wakes and the boat is moving forward so the tower trys to pull you up to it level whereas an ordinary pylon wouldpull you down.....


...i think

[wakeboardwillis]

It depends on how much stress in on the line.

[JV]

Okay, follow me on this. It's actually a very simple right-triangle equation:

The ONLY forces acting on you after you leave the wake (neglecting wind resistance) are gravity and the tension of the rope. Now, given that you are using a 75-foot rope with a tow point on a tower that is 5 feet above the handle, the rope makes a 3.8 degree angle above horizontal (determined by the inverse tangent of opposite over adjacent). You can then use this angle to determine the upward pull of the rope. At 22 mph boat speed, the vertical component of the rope's force is the tangent of 3.8 multiplied by 22 which equals 1.47 mph. Lastly, divide that by the downward acceleration due to gravity, or 79,000 mph per hour, and you are left with 1.86 * 10^-5 hours, or .067 seconds.

In summary, if you were to take an identical cut and get the same pop behind the same boat (one time with a tower, one time with a tow point even with the handle) with the same wake and the same rope length, you would have .067 seconds longer to reach your peak height before the rope--and gravity--forces you to descend. To solve how much higher that is, subract .978 (determined by plugging in abritrary numbers into the distance equals velocity * time equation) from 1 to get .022 which is equivalent to 2.2%. Therefore, even with a good wake jump of 10 feet high behind a towerless boat, you'd only expect to get about .22 feet, or 2.62 inches, more height if you had a tower.

Congratulations to those of you who chose 0% to 5%, you are correct . You can argue with me all you want, but I didn't make any of those numbers up (check them for yourselves). So, there it is, towers do next to nothing in regards to jump height. However, like Ctipping said, towers do noticeably increase hang time by making the curve of travel more gradual. With a tower, you're path of travel would be closer to a half-circle than the steep arc of a towerless jump.

I apologize for causing any of you high school physics flashbacks.

[midwesty]

i am now smarter for reading this, thank you

[JV]

midwesty, i do what i can. now, if you'll excuse me, i'm going to go find the nearest apartment kegger and kill off a few of these useless information brain cells

[STPHNSN23]

NERD ALERT....

[JV]

haha, yeah, pretty much. actually, those calculations are about 100 times easier than the stuff i'm doing now, so i breezed through those numbers in about 30 seconds. and i thought i'd never use this stuff in the real world...

[d-dub]

!!!WARNING--SERIOUS GEEK ALERT!!! May cause drowsiness, headaches, and vomiting! Do not read while driving or operating heavy machinery!

Criminal,

As you have invited in your last paragraph, I have checked your numbers and I do have some arguments to make, and, although you indeed may not have made any of those numbers up, the mathematics and rational you used to derive them seem to be a little off. Yes, the first and easiest step in calculating this out is determining the vertical and horizontal components of the pull of the rope through trigonometry or ratios or the Pythagorean Theorem or whatever your method of choice might be. You made an error here in that you used he inverse TANGENT of 5/75, whereas you should have used the inverse SINE of 5/75. The rope is your hypotenuse, not your adjacent leg. Rearranging the Pythagorean Theorem, the adjacent leg length is the square root of (75^2 - 5^2) = 74.83', not 75'. But, you got lucky, because at small angles, sines and tangents are nearly identical since the hypotenuse and adjacent legs are nearly the same, so to 2 significant figures, the angle is still 3.8 degrees. But this was a simple mistake that was easy to make. My real problem with your numbers comes with what you did next. This is the part that I have toyed with in my head many times, and is where the difficulty comes in. It is calculating the force in the rope, and then translating this into an increase in air time and height. You calculated the vertical component of the rope's FORCE from the speed of the boat in units of mph, which are units of VELOCITY. Not only are force and velocity obviously not the same thing, but I don’t think the boat's velocity has anything to do with it, other than effecting the additional tension created in the rope from the wind resistance on the rider, which you chose to ignore anyway. (Wind resistance increases at the square of an increase in speed.) And, if you are ignoring wind resistance while in the air, the rider can let go of the rope and keep traveling forward at the same speed as the boat, as guaranteed by Newton's laws of motion. This basically proves that the boat speed has nothing to do with the numbers you are trying to run. Then, I assume to make the units work out and knowing gravity plays a part, you divided by the acceleration of gravity to get a result in units of time. Then you rationalize that this time is the extra time it takes to reach your peak. How did you determine it was the peak rather than an increase in total hang time, or some other reference time for that matter? This time was also derived regardless of whether the rider would have otherwise gotten .05 seconds of hang time or 1.5 seconds of hang time without the help of the tower. This is significant, because this translates into 268% more hang time referencing the former and only 8.9% more hang time referencing the latter (assuming the same extra .067 seconds that you calculated is realized on the way down too.) Then, through a method that you don't thoroughly explain, you convert this extra time into a percent increase in height. Then, you make the final statement that although the tower does next to nothing to increase your jump height, it noticeably increases hang time. Not only are height and hang time directly related, but a few sentences before this you said you have .067 seconds longer to reach your peak, which I don't think most people would classify as necessarily a noticeable increase in hang time. Also, the path of travel relative to the rope's tie-off point, which is a parabola (ignoring the constantly changing upward or downward force of the rope as your height changes, throwing this off a little), will still be a parabola regardless of the height of the tie-off point. I'm not trying to sound nasty, but perhaps you need to reconsider your statement that this stuff is 100 times easier than the other stuff you are doing, and give it a little more than 30 seconds of time. There is actually a lot going on with the dynamics here that you didn't even consider, such as the centripetal force caused by the circular path of the rider relative to the boat, wind resistance, loading the line while boosting off the wake (which can be used to slightly increase the initial vertical velocity), and loading the line while in the air through stopping, initiating, or reversing body rotations during tricks like raleys and rewinds. Not only that, but the elements you did consider do not appear to have been considered correctly. I assume you are in college by some of the things you said. If you are in a dynamics or physics class, I'd like to know what your professor's opinion on this question is. As a side note, your final result isn't too far off from mine, but that is simply because we are dealing with small percentages of small forces in the rope, which as you saw with your error in using the tangent instead of the sine, doesn't amount to a hill of beans at small angles. If you want to dig a little deeper and run some more numbers, or if you see any problems with what I have stated here or have misinterpreted anything you have said, again, I'd like to see some more comparisons.

D-Dub

[JV]

obviously, these are crude numbers and a hundred other factors come into play, but i feel my conclusions will at least be close to what actually happens. you did catch me on the inverse sine part. thanks. as far as the velocity vs. force thing, i realize velocity isn't a force, so i explained myself poorly in that regard, making it seem like i was solving for the force of tension. tension i never touched on as, theoretically, you can achieve nearly equal tension behind any stationary tow point, so loading the line is irrelevant. in fact, i just treated the rope as a cable. i was using the triangle to determine vector components where speed of the boat does matter, creating upward "momentum" on an angled rope. i only calculated for the instant you leave the wake because i believe the rope does little to effect your height after the initial "pop" (the rope does have an effect after that, obviously, but the variables--trick type, trick height, etc.--are too numerous to calculate when considering its limited, almost neglible, effects on actual height after the rider leaves the wake. in fact, the way i solved it, in practice, would be a rider dropping the handle moment he/she leaves the wake--which would greatly effect the horizontal distance traveled, but not so much the peak height). for instance, if you were to leave the wake with an upward velocity of 10 mph behind a boat with a towpoint directly parallel with the handle, a tower 5 feet above the handle would add 1.47 mph to that. thus, you would continue traveling upward for .067 seconds longer.

in this case, i do not believe hang time and peak height to be directly related. while i did nothing to prove this, it seems to me towers create more of a swinging, pendulum ("floaty" if you will) motion that decelerates the effect of gravity. (here is where you can see centripal force at work). much like the softer landings and floaty air tricks at a cable park, but on a smaller scale. both will be pendulums, but without a tower i'd think it would be a little steeper, albeit probably not detectable by eye. so, in that sense, you could have similar peak heights with noticeable difference in air time (by noticeable i mean tenths of a second--if that). that's why cable riders can do tricks boat riders can never dream of even when boat riders can get more height.

so, the calculations i did WERE easy because of their basic and crude nature. i never claimed for them to be the be all end all in the discussion, but they are a moderately accurate estimation of what one can expect. if i presented them to be the final word, i apologize. i realize considerably more complicated things also come into play, but i'll leave those for you to spend way too much time on only to come up with answers congruent with the simplistic case. i don't pretend to be a genius, but i thank you for pointing out all the BS in my post . if i didn't have exams to study for, i could come back to you with much more scientific and precise results--likely no more than a few tenths of a percentage point different--but i've spent way too much time on this as is

[Mariner]

JV and d-dub,
Well done both of you. No need to get snippy. We can all retire to the nerdery with our calculators with Richard.

A different but related topic, though more relevant to my life, is the benefit of a tower/pylon to getting someone up on out of the water. A friend of mine is about 240 lbs and has a 90 hp outboard on his 16 foot Invader. I told him that it would make his life significantly easier to be pulled up w/ a tower/pylon vs a tow point at or just above (1 foot or less) the water level. I am just guessing that a tower/pylon would enable him to get out of the water in about half the time behind the old trusy straining outboard.

Any calculations or comments to prove/disprove my theory?

I know all of you have brand new Malibus, but we poor folk up here in northeast Houston have to work w/ what we have. kidding.

[JV]

Mariner, there's no doubt an extended pylon or tower make it easier to get out of the water, but that wouldn't be my primary reason to get one. i'm no lightweight either (205 lbs. give or take), but, once i learned the proper technique, getting up behind any boat--even at slow take-off speeds--was a piece of cake. it only takes 5-8 mph or so to get the board on plane; once on plane, it doesn't take much strength to pull yourself through the water; the best advice i got was to get the board on plane as soon as you can underneath the water while keeping your butt near your ankles. after that, your friend can just stay crouched until he's comfortable with the speed. when i was riding behind our under-powered bass boat (with a tow point inches off the water), i'd stay crouched for a hundred feet before finally standing up. it doesn't look as cool as popping out of the water like you do with a tower, but it works.

[d-dub]

Mariner,

Most of my riding growing up was behind a 15 ft boat with a 55 hp motor, so I sort of know where you are coming from. The main difference was I weighed half of what your friend weighs. Unfortunately, it is my opinion that for reasons I and JV have touched on, the tower would help, but only very little--say in the neighborhood of less than 5%. Essentially, its not going to make a significant difference. If you really want the help of being able to pull yourself up, you need to use a barefoot boom with no rope or a very short rope, but most people, including myself, don't have access to one. The biggest help will be technique, but it is going to be difficult and frustrating to learn the proper technique when you are struggling with a low powered motor. I learned my first deep-water start in 1989 on a plastic yellow Skurfer Launch after an entire summer of failure. However, I was able to ride a few times before that doing a sitting dock start, which is MUCH easier for a newbie than a deep-water start, which I can personally attest to. Getting to ride using a sitting dock start helped me later learn the deep-water start by learning what it felt like to ride and what the end result of the deep-water start needed to be. If you aren't familiar with a sitting dock start, find a floating dock, sit on it with your board in the water and the ski handle in hand, have the boat inch away until the rope is taught, and then have the driver take off. The rider is already up and out of the water in what is pretty close to the final riding position, and it makes things very easy. Another thing that we would do to get bigger riders up behind small outboards on deep-water starts was as follows: Position the rider in the water out to the side of the boat instead of directly behind the boat, but with the rope still taught, then have the driver take off. This gives the boat a chance to build up some speed and begin to plane off some while gradually taking on the increased pull of the rider in the water. The rider will have to deal with a more gradual pull at first, and the angle of the rope will rotate on him a bit, but it may help. If your friend rides left-foot-forward, put him to the left (port) side of the boat. If he rides goofy, put him on the right (starboard) side. Combine all of these things with the technique tips given by JV, and hopefully it will all come together. As the boat takes off, try to position yourself and the board less like a bulldozer and more like a squatted surfer. Allow the pull of the rope to rotate your body from a horizontal lounged position to a closer-to-vertical squat position with the board underneath you and nearly flat instead of out in front and on its side. This will hopefully allow him to plane off instead of plow water.

D-Dub

[Mackr0s]

d-dub, it would be nice if you could try a paragraph or two. Other then that, its has been a fun read.

[burntorange77]

Hello everyone, I'm Mariner's fat friend, 6'3" 240lbs and all man. Just so y'all know I've been able to grind it out and get up from a deep-water start behind the 45hp that he talking about. Once I planed out it was no problem, but getting there wasn't easy at first. It did teach me some good technique though. So I figure getting up behind my 85hp will be a breeze. Plus, my Invader has a much deeper V hull and is a lot heavier, so the wake should be quite a bit bigger as well.

[intotheflats]

How many times can this be brought up?

http://forums.wakeboarder.com/viewtopic.php?t=48082

Please make it stop

[JV]

intotheflats, it will never end because smart asses (like me) will swear by one thing and other smart asses will swear by another, and no one ever can admit to being wrong. the problem is, few people have ridden behind the same boat with and without a tower. oh well, atleast it's a somewhat friendly debate compared to all the other trivial boat arguments that pop up on this site

[Brit Rider]

Some really interesting points being raised here... and some clever maths being brought up too.

Just seems like the variables are being taken into account properly.

Basicaly I used to ride behind a Maxum without a tower... then we added one so have a direct comparison to draw from.

Put simply I got a lot more hangtime once the tower was added.

From jumping probably 3 metres wake to wake I went to 4 metres.. and gained a little height.

The real important thing that does't seem to be getting taken into account (or maybe i'm just not realising it is!) is the way in which the rider pulls the handle when using a tower. this pulling of the handle down to the front hip really seemed to aid me in going further. Without a tower I was simply pulling myself into the water quicker.

When the line is attached higher up its not really giving much more height to the rider but it clerly adds distance to the jump.

[nfn]

JV,

[JV]

nfn, i'm assuming identical cuts behind an indentical boat. so if you were to take an aggresive, into the flats cut and get one full second of upward motion behind an extended-pylon level with the handle, it would be about 1.067 seconds with a tower. the .067 seconds doesn't equate to an identical increase in height regardless of what trick you're trying because of what you were talking about. with a raley-based trick--with an expected greater upward velocity than an ollie pop--that .067 seconds would have a bigger impact on height than w2w tricks.

Brit Rider, are you sure you didn't just get better between the time your boat didn't have a tower and when it did? i do agree towers make it much easier to go further into the flats. in regards to holding the handle next to your hip, the higher the tower, the more beneficial the handle is to you, but when you're dealing with such miniscule angles (3.8 degrees extended pylon to tower), it's not a profound effect on height. (if you had a tower 30 feet tall, you'd be flying). with a towpoint significantly below the handle, maybe a normal tower would make more of a difference, but there's no way i'm going to solve for that

[dirtyohioriver]

i always bitched about not having a tower now it makes me feel bette rthat it dosnt really matter

[Brit Rider]

JV, just one other thing when working out the angle... quite often when using a standard bakc of the boat ski bridle or tow eye the rope isn't horizontal.. it often slopes down to the boat from the rider.

I went straight from tower less to having a tower... within 3 days and I am positive that there is a clear difference... I'm not saying its huge but its gotta be more than 5% as being suggested...

[JV]

brit,

i'm sure it would be more than 5% going straight from a tow point significantly below the handle (at the top of the wake) to a tower. but i'm too stupid to do any calculations other from a pylon directly even with the handle . 3-4 meters high? damn, i wish i could do that, tower or not

[Brit Rider]

JV,