What is the effect of a low sand pit on long jump distance? I know some places uses those hard 2″-3″ thick all weather surfaced sand pit covers which cause the sand to be at least 2″-3″ lower than ground level. What is the general effect of say a 3″ low pit on performances (how much benefit)? I have worked this out before by myself but I want to know others’ thoughts. I am just bitter because every meet we’ve gone to this year has beautiful sand at ground level while I have seen footage from some meets where it’s ridiculously low.
Effect of low sand level?
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Participant
Mort,
What have you come up with when you worked it out yourself? Were you at Susquehanna on Friday?
I had one of my jumpers figure it up a few years ago during physics class. It was something like 2″ distance for every inch of “lowness”. I think this was based on like a 9m/s takeoff and a 20degree takeoff. I think the result she came up with is close at least. And yes, we are always at Susquehanna.
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Participant
I feel the same as you for this season. Although I am only working with our multis that jump it seems like everytime they do we get even pits and I see marks from others in our conference where they get a 5inch drop.
I thought you coached at Juniata, but I wasn’t sure. Are you going to be there again this Saturday?
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Participant
I feel the same as you for this season. Although I am only working with our multis that jump it seems like everytime they do we get even pits and I see marks from others in our conference where they get a 5inch drop.
I thought you coached at Juniata, but I wasn’t sure. Are you going to be there again this Saturday?
Yea I will be there this week too unless I have to go on travel for work. If you want low sand, go to Albright. I am dead serious. I was there for a masters meet a year or two ago and was too scared to long jump. It is (or was) insane.
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Participant
What is the effect of a low sand pit on long jump distance? I know some places uses those hard 2″-3″ thick all weather surfaced sand pit covers which cause the sand to be at least 2″-3″ lower than ground level. What is the general effect of say a 3″ low pit on performances (how much benefit)? I have worked this out before by myself but I want to know others’ thoughts. I am just bitter because every meet we’ve gone to this year has beautiful sand at ground level while I have seen footage from some meets where it’s ridiculously low.
I agree with you guys that 1 inch down = (roughly) 2 inches more on the jump give or take the level of the athlete. Last year, my long jumper lost a significant amount of distance at a meet due to the sand being about 3 inches high.
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Participant
Never have tried to run the numbers but after 27 years watching mine & others, I’d say the 1:2 ratio is a bit generous but close enough for discussion…
Remember, flight & extension mechanics are timed up from their pre-experienced/pre-existing motor program and the lesser the performer, the more they will hunt for a landing based on their program regardless of the week’s venue.
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Member
For a vacuum trajectory (no wind drag) the jumpers horizontal velocity will be constant after takeoff and be equal to cos(takeoff angle)x(total velocity at takeoff). The vertical velocity at takeoff will be the sin(takeoff angle)x(total velocity). This component will slow (due to gravity) and then reverse, so that when the jumper is again level with the takeoff ramp it has become negative.
At this point (when you are interested in) if we ignore continued negative vertical acceleration due to gravity (suitable for relatively small differences in height) then the ratio of forward to downward progress is: cos(takeoff)/sin(takeoff)
For 20 degrees: cos(20)/sin(20)= 2.7
With wind drag and considering gravity in more detail it will be slightly less, so 2:1 is a good estimate. -
KeymasterYesterday, two of my post-grad athletes competed at a facility where the sand was about 3-4″ HIGH. I complained to meet management and managed to get it down to about 2-3″.
ELITETRACK Founder
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Participant
I will now make my attempt at taking cfka’s title of super-ranter.
The key to great jump marks in division III are:
– extremely low sand
– measuring from the wrong end of the board
– misreading the tapeKey to poor marks are:
– measuring with a tape where the metric 0 is 1 foot into the tape
– measuring from the far end of the foul plasticineIn the past 1 or 2 seasons I have had the following occur:
1) Triple jumper jumped something like 18.97m due to a totally illogical official error. it was actually recorded (I just had to let that one slide :)) then later my best long jumper flipped out and asked how a 40′ triple jumper just annihilated the world record.2) I had 3 jumpers seeded around 6.80m. Officials actually made snide comments after their jumps about our seeding procedures when they were all jumping 6.30s. Hearing that, I promptly informed them that 0 on their metric tape started a foot into the tape. This has happened at least 5 times in the last few years (usually minus the snide comments).
3) At conference my long jumper was in second place going in to the last round. A lower ranked jumper jumped and the official measured from the wrong end of the takeoff board. I know because I was standing right there and saw the tape. After I told him he just randomly measured from the wrong end he yanked up the tape and promptly denied it. This official was later seen at a bigger meet measuring EVERY jump from the wrong end. There were a lot of happy jumpers and national qualifiers that day. I informed the meet director and his solution was to let all prior marks stand but future marks would be measured correctly. So if you jumped early, you got a free 20cm.
4) Old women officials clearly marking 2″+ fouls and fouling legal jumps.
If you can weather these circumstances and still have brainpower left, then you can be an effective division3 coach.
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Participant
All I know about vacuums is my wife (former 300lb 1/2 Squat) cant seem to push one.
Humor aside, they are going to put the landing gear down when they think its time to. Total grains of sand “below sea level” provides an oportunity but in most cases it wont change the likely result much.
Mort, oddly enough my father’s middle name was Mort(imer) Your attempt at ranting “up a weight class” was a fine effort but I find it lacking the edginess that results from years spent in the purgatory of one’s assumed brilliance. Keep toiling, there’s potential in your work. I honor your effort with an extremely rare :coolsmile:
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Keymaster
I don’t know CFKA….Mort has been challenging for the title for quite some time.
Regarding the actual topic at hand, I tend to think in light of CFKA’s remarks, high sand has a greater affect on performance than similar discrepancies on the other end of the spectrum (low sand).
I’ve got an athlete now whose takeoff / flight / landing mechanics are not super consistent and the difference of 1-2″ of sand can make a fairly big difference. I think it really is possible to “barely miss” the landing (timing it up that is) and have it cost more than the above mentioned 2:1 ratio.
ELITETRACK Founder
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Participant
That pit this weekend was still TOO high we would have been better off jumping into a port-a-pit.
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