BS: Jumping into lakes?

Subject: RE: BS: Jumping into lakes?
From: JohnInKansas
Date: 17 Feb 12 - 04:03 PM

The "scientific" explanations about surface tension and stuff have all been disproven by "real science." The "effects" have been quantified, and are negligible at all impact velocities up to "free fall terminal" speeds.

It still is good advice to "see the surface" in some cases, for experienced people, because the ripples produced by even a small surface disturbance are sufficiently different for very shallow water than for deeper water, so for water less than a very few feet deep you can (but aren't likely to know how to) "read" the depth from the ripples. This won't tell you whether the water is deep enough to dive safely, but can confirm that you're not diving into a mere mud puddle.

In swimming pools, since the sidewalls and bottom are nearly always painted (or tiled) the same color as what you expect to see when the pool is full, it can be hard to tell if there's any water in the pool if there are no ripples, and significant numbers of people are injured (or killed) every year by diving into empty pools where they assumed there was water. In most pools, it's unnecessary to toss a pebble, since the circulation/filtration system will make enough ripples for the surface to be visible. If the pool is "completely flat" it probably means that the filters are shut off, and the pool is still polluted from the last person whose clumsy dive knocked the pee (or poo) out of him/her, so that might be almost as good a reason for not diving as the possibility that the pool is empty.

(See the movie, Caddy Shack, that hilariously dramatized the folk warning that in a public pool you "don't eat the Baby Ruth?")

John

Subject: RE: BS: Jumping into lakes?
From: Penny S.
Date: 17 Feb 12 - 08:42 AM

Teehee!

Subject: RE: BS: Jumping into lakes?
From: frogprince
Date: 03 Jan 12 - 11:37 PM

Picture of 999 with a water softener

Subject: RE: BS: Jumping into lakes?
From: GUEST,999
Date: 03 Jan 12 - 05:06 PM

At this time of year in Canada, it's very important to break the flat surface. It's ice!

Subject: RE: BS: Jumping into lakes?
From: Penny S.
Date: 11 Feb 09 - 04:58 PM

Barry, it was just that you echoed what I was told so closely that I suddenly wondered if you were one of the guys from the pool, when I had been thinking that the closeness was an indication of the widespread understanding of the idea, so I was eliminating that possibility.

Penny

Subject: RE: BS: Jumping into lakes?
From: Newport Boy
Date: 11 Feb 09 - 11:32 AM

One well-known jumping spot is near "our" beach on Gower, South Wales.
Blue Pool is a tidal rock pool about 5 metres across with a sandy bottom, variously measured at 2.5 to 4.5 metres deep (although the locals say it's bottomless).

My grandson, here, is jumping from the left side of the previous photo, about 3 metres. There is a video clip on YouTube of someone jumping from the high rock in the centre of the pic. I hope he wasn't as drunk as the cameraman appears to be!

Phil

Subject: RE: BS: Jumping into lakes?
From: GUEST,leeneia
Date: 11 Feb 09 - 10:01 AM

I grew up in Wisconsin, where there are many lakes and many diving injuries. I've done a lot of diving, and I don't believe a word of that stuff about not breaking the surface of still water. It's just a film of water a few molecules thick.

I do think there could be something to the statement above that it is hard to judge the depth of still water. A sensible person would go by the numbers written on the side of the pool, not the look of the water.

However, the very words 'diving into a lake' give me the willies. Read this:

"Diving Injuries
Giuseppina Di Meglio, MD*

* University of Rochester School of Medicine and Dentistry Rochester, NY
Diving injuries are an important cause of spinal cord injury (SCI) in adolescents. Each year, 10,000 to 20,000 people suffer SCIs. Adolescents aged 15 to 19 years are at highest risk. Motor vehicle accidents and sports injuries—two thirds of which are diving injuries—are the leading causes of SCI in this age group. Boys are at higher risk for all types of SCI and are up to 18 times more likely than girls to sustain an SCI while diving [RR = 17.9 95%, CI 7.6 to 42.1]. Between one third and one half of diving injuries are associated with alcohol consumption. Other illicit substances probably contribute to the risk of injury."


Don't dive into water unless it's clear, unless you know how deep it is, and unless you know there are no rocks, abandoned cars, or other hard objects in it.

Subject: RE: BS: Jumping into lakes?
From: Barry Finn
Date: 11 Feb 09 - 08:22 AM

Not in Kent but here I passed my lifesaving/guard certs at the age of 16 & my daughter is licensed/cert by the red cross to train others to teach swimming & lifesaving & hires out as a lifeguard during the summers to help herself through college. I've been a NAUI sanctioned SCUBA diver since 1979, my brother was a navy seal who specialized in underwater welding & XXXX, my momma is a walrus but she's not in Kent either.

Barry

Subject: RE: BS: Jumping into lakes?
From: Penny S.
Date: 10 Feb 09 - 05:45 PM

Barry, you aren't a lifeguard in Kent, are you?

Subject: RE: BS: Jumping into lakes?
From: Penny S.
Date: 10 Feb 09 - 05:37 PM

Hmm. Barry uses the same phraseology and explanation as the pool guards, and as I didn't give all the details, that shows that they weren't spinning a yarn. But I couldn't find any reference on the net - breaking the water usually refers to labour processes. Surface tension is due to hydrogen bonds between water molecules, which are pretty weak, so I doubt that that is what is entailed.

Odd.

Penny

Subject: RE: BS: Jumping into lakes?
From: Big Andy
Date: 10 Feb 09 - 11:42 AM

I took the bike for a spin a few years ago up to Kendal and had a stop off at devils bridge for a bovral and a bacon butty. Now this been a well known bikers stop i thought that the air ambulance was there for a bike accident, but when the police and ambulance went all became clear when all the teenagers striped and jumped off the bridge, it seemed a lad had jumped and missed.
Makes you wounder if it might have helped if he through a stone over first to break the surface tension of good solid ground, or if this was Darwin's thierry in progress

Subject: RE: BS: Jumping into lakes?
From: Snoozer
Date: 09 Feb 09 - 01:52 PM

I saw that Mythbusters episode, and the myth was "busted". All I can recall is that there was no difference between jumping into "rippled" water or flat water. But I don't remember any of the details.

Subject: RE: BS: Jumping into lakes?
From: Jim Dixon
Date: 09 Feb 09 - 11:42 AM

Mythbusters, Episode 5, Oct. 24, 2003:

"Can Jamie and Adam cheat death? We'll find out. First, they test the theory that a person could survive a leap from a bridge by throwing a hammer in the water first. According to urban legend, the hammer should break the plane of the water's surface, thereby softening the landing...."

I guess you'll have to rent the video to see the result, or wait till it comes around again in reruns.

Subject: RE: BS: Jumping into lakes?
From: Jim Dixon
Date: 09 Feb 09 - 01:27 AM

I've read that it was once a common belief among sailors that sea water was poison, and that if you swallowed even a mouthful of it, you'd die.

Familiarity with something does not preclude believing in old wives' tales about it. (Sorry for the sexist language.)

Subject: RE: BS: Jumping into lakes?
From: Rowan
Date: 08 Feb 09 - 06:20 PM

Just make sure the water's deep enough to avoid compressing the C6-C7 joint when you dive. Unless you want to qualify for Murder Ball, and even then you'd have to work on getting arm movements back.

Cheers, Rowan

Subject: RE: BS: Jumping into lakes?
From: Barry Finn
Date: 08 Feb 09 - 06:08 PM

I didn't know at the time to squeeze my butt cheeks but I did go feet 1st, it didn't help my ass at all though.

hanks Bee for the scientific explanation, helps with the understanding.

Barry

Subject: RE: BS: Jumping into lakes?
From: gnu
Date: 08 Feb 09 - 03:41 PM

Kendall... there's Canuck comic that does a routine called "Swimming Back to Shore". This is the lad.

Subject: RE: BS: Jumping into lakes?
From: Mrrzy
Date: 08 Feb 09 - 03:19 PM

Also squeeze your ass shut. That can really avoid additional pain if you're going in feet-first.

Subject: RE: BS: Jumping into lakes?
From: Bee-dubya-ell
Date: 07 Feb 09 - 09:48 PM

"It is true that you should break the water before juming in"

but WHY?

It's called surface tension. It's the same force that makes liquids form drops, allows water striders to walk on water, and makes thrown stones skip. It's at its maximum when the surface of a liquid is still and unbroken. Under those conditions, it sort of transforms the surface of the liquid into something akin to an elastic membrane. It increases the surface's resistance enough that someone moving with enough velocity (say after diving from a 100 foot cliff) may encounter enough resistance upon impact to cause injury. If it were to cause loss of consciousness the person would probably drown.

Subject: RE: BS: Jumping into lakes?
From: Barry Finn
Date: 07 Feb 09 - 09:14 PM

Why?
Because hitting flat qwater from heights would be akin to hitting a fl;at surface at a lower high. If thw water is unstable it's not going to ba flat & is already broken which allows you not to have to break it upon entering it. If you've ever leap from a high spot into flat water your feet will know the difference between rippled water & flat water. It feels solid & sometimes your legs feel as if they've been drive up through your hips. I once went off a quarry from a pretty high spot into flat water & it felt like a telephone was jamed up my ass. It was very painful.

Barry

Subject: RE: BS: Jumping into lakes?
From: kendall
Date: 07 Feb 09 - 08:34 PM

Gnu, my older brother also taught me to swim. He took me out in a boat and pushed me overboard. Swimming ashore was the easy part; getting out of that damn sack was the bitch.

Subject: RE: BS: Jumping into lakes?
From: michaelr
Date: 07 Feb 09 - 05:33 PM

"It is true that you should break the water before juming in"

but WHY?

Subject: RE: BS: Jumping into lakes?
From: Barry Finn
Date: 07 Feb 09 - 04:53 PM

It is true that you should break the water before juming in, but not into a pool. It's practiced when diving from much higher heights. Off roofs, cliffs, bridges, ships & such but usually in situations like that the water's already in motion, so it's seldom ever warranted. When I was a kid we used to dive off cliffs (& all the others things except for ships that I just mentioned) into quarries & because of the high surrounding cliffs (over 100' in places) the wind never got to moving the water so we'd all use boulders, rocks & pebbles just didn't cause enough motion.
I though everyone knew this but I was raised in & on the water.


I got caught running across RT 28, where it went over Bass River (maybe 75') on Cape Cod as a kid (12) by my aunt. When she got home she told my mother she saw me run across the road, clear the rail like superman without touching it, & dive head 1st off the bridge into the river. My mother was ready to shoot me when I got home but my grandfather met me at the door & said he heard I was diving off the bridge. I admitted "yup". He said there were many men during WWII that were afraid to up from the heights of ships that were sinking & because of that fear they drown instead. He told me he was pleased to know that if I were ever in a war I wouldn't die from fear of juming off of high places. I got to avoid the oncoming punishment that I didn't yet see coming. God bless Grandfathers.

Barry

Subject: RE: BS: Jumping into lakes?
From: gnu
Date: 07 Feb 09 - 04:49 PM

I remember my bro teaching me to swim. He jumped in and swam about, talking to me all the time, telling me what he was doing. Then, he joined me back on the wharf and threw me in. He was still telling me what to do and encouraging me. But, I didn't hear much of it as I struggled to get back to the nearest ladder.

Being an older brother and wanting me to learn, when I had climbed nearly up onto the wharf, he shoved me arse over tea kettle back into the water. That is when I learned to swim... to the next wharf.

Subject: RE: BS: Jumping into lakes?
From: Newport Boy
Date: 07 Feb 09 - 04:43 PM

The reason for wanting ripples on the surface of the water is to give you something to focus on. It's very difficult to judge the distance to flat calm water from above.

I don't know this from any experience of diving - I don't do water for pleasure!

Phil

Subject: RE: BS: Jumping into lakes?
From: Will Fly
Date: 07 Feb 09 - 03:50 PM

I've jumped and dived into perfectly still swimming pools for over 50 years...

Subject: RE: BS: Jumping into lakes?
From: Q (Frank Staplin)
Date: 07 Feb 09 - 03:35 PM

Your pool manager should hire lifeguards, not comedians.

Subject: BS: Jumping into lakes?
From: Penny S.
Date: 07 Feb 09 - 03:25 PM

Last Friday a couple of young lad lifeguards at the pool told me something as if it were general knowledge, and I found it puzzling. I tried to google it, but no mention.

The pool was dead flat, still, and commented that it was nice to see it like that. They said that for safety, before getting in, it was necessary to "break" the water and cause ripples. Or jumping in could cause damage. Worse than belly flops. They said that people on mountains would drop a pebble to do this before jumping into lakes.

I expressed some doubt, and suggested that jumping into mountain lakes was probably safest done by not doing it at all, and said I would check it out.

Has anyone heard of this? I can imagine that it would be hard to belly flop on water with large waves, but not teeny ripples. I can imagine that it is probably easier to estimate the distance to the water with ripples on it, while being harder to see any hazards under the surface.

I still doubt this. Any ideas?

Penny