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float test

paul wheaton
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Joined: Dec 14, 1998
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    ∞

My son starts a sailing class on Monday.

Before he is allowed to take the class, he must pass a "float test". For ten minutes he needs to stay afloat, fully clothed, in a pool. Then put on a life jacket.

He made it for two minutes.

The trick is - he sinks!!!

I jumped into the pool (with my clothes on) and showed him. Take a deep breath. Hold it. And I float. .... He takes a deep breath. Holds it. And sinks to the very bottom of the pool.

He's a skinny kid. Almost zero fat.

The lifeguards say that skinny kids can do it, but he is tensing up. He does look like he is working a little too hard to keep his head above water, but I kinda wonder if he just has to do that - he's just not as bouyant as the rest of us. The lifeguards say that if he relaxes, he will float.

I cannot wrap my head around this .... I guess if you relax, you will be less dense than water? But if you are tense, you are more dense than water at 12 feet deep?

Anybody have any advice? The class starts monday at noon. He has monday morning to get this figured out.


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Bert Bates
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    5
Wow Paul... 9999...

Okay - when I was in scouts we learned "drown-proofing".

You float with your face in the water (like a jellyfish) - every 20 or 30 seconds, you gently push your face up by pushing your hands down, take a breath, then put your face back in the water. We had to do it for an hour (the sensory deprivation is pretty trippy after an hour ).

I think it would even work for a 0 fat marathoner!


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paul wheaton
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Joined: Dec 14, 1998
Posts: 20276
    ∞

That's what I showed him when I got in the pool. The dead man's float. Take a deep breath. Hold it for 20 to 30 seconds and relax. You float. Repeat for hours. When he tries this, he ends up at the bottom of the 12 foot deep pool.
Jim Yingst
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Well, tell him to take a really BIG gulp of air, because that's probably the main thing that can help him with this bouyancy thing. And you might want to review what exactly he is wearing, on the off chance there's something particularly dense which maybe he should not wear for the float test.

In the longer term... start feeding him fatty foods. Anyone who can't float in water with a full breath of air is TOO DURN THIN. Fatten him up.


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David O'Meara
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Joined: Mar 06, 2001
Posts: 13459

I think Jim's advice is the best - try to move things in his favour by finding biyant clothing.

But yes, I have heard stories of people whose natural boyancy is slightly different but enough to change their behaviour in water. Saw video of people who could float in regular salt water as if it was the Red Sea, no reason I can see that the opposite can't be true.

Ask if he can do the test in a wet suit, I think they float slightly. It may also be worth taking a hint and making sure he always has a vest or something when sailing.

Amusing stories later, safety first.
paul wheaton
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Joined: Dec 14, 1998
Posts: 20276
    ∞

He has to take the test with the clothes he will be wearing on the days he is sailing. And I'm pretty sure he will be wearing a vest - this is a safety measure.

The thing that gets me is the two lifeguards that were trying to give him advice. Both said that they have seen this before. And it can be overcome. They insist it is all mental.

I suppose it is possible that your mindset can impact your bouyancy. Bouyancy would be based on density. If you were to tense all of your muscles, it does seem that you would be smaller (and thus, more dense).

On the other hand, he did seem completely relaxed as he sank to the bottom of the pool with his lungs full of air.

Who knew heavy thoughts could make you sink!
Jeanne Boyarsky
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Do they define "float" as being relaxed and completely still or can he move a bit?

When I try to do a backfloat, my legs start to sink after about 30 seconds. If I don't do anything about this after a while, my whole body sinks. They way I deal with this is to move my legs a tiny bit when I feel them start to go down. Just a little side to side motion. If I do it slowly, I don't move backwards.

I haven't done dead man's float in a number of years, but a similar thing happened (when I was in the skinny kid phase myself.) I needed some leg movement to stay up.

I'm actually surprised they want dead man's float for 10 minutes instead of treading water for 10 minutes.


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Marilyn de Queiroz
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  10
I agree with Jeanne. I used to have to move my feet occasionally (not constantly) to stay afloat. Another thing that helped sometimes was letting my legs bend at the knees to let my feet drop. this changes the center of balance more to the chest rather than the hips, and, of course, the chest is the inflated portion of the anatomy.


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Jim Yingst
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Um, yes.

We need a "biting my tongue" smiley here.

As I recall, the basic principle of the float test is that if the subject floats, he/she is a witch, and if they sink, they're not a witch. This suggests that one could take up witchcraft to improve buoyancy.

[Paul]: I cannot wrap my head around this .... I guess if you relax, you will be less dense than water? But if you are tense, you are more dense than water at 12 feet deep?

Well, maybe. For what it's worth, the depth is irrelevant here; the density of water doesn't change perceptibly with depth. Other than that - I suppose it's possible that tense muscles are denser than relaxed muscles, enough to make a difference here. But that seems unlikely to me. I think it's more likely that when people panic in the water, they flail about, and if they don't know that they're doing, their movements may well drag them under rather than keep them up.

Paul, when your son sinks - is he moving at all? If so, can you get him to be completely motionless and see what happens? I remember having some trouble with the dead float when I was a kid (until I learned to make a point of taking a really deep breath), and I remember letting myself sink, hitting bottom, and pushing off to reach the surface to take another breath. Not that this is the most efficient way to do things of course, and it's useless in deeper water, but it's a way of getting comfortable underwater and knowing that you have a way to keep breathing reliably. Might be worthwhile to practice this for a while until he's more relaxed underwater.

Also, how are his swimming skills aside from this? Can he get around OK when not doing this float test?
marc weber
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Originally posted by Jim Yingst:
...As I recall, the basic principle of the float test is that if the subject floats, he/she is a witch, and if they sink, they're not a witch...

Yes, water will almost always reject a witch. However, this test is from the dark ages. Nowadays, a simple blood test is used.


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paul wheaton
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Joined: Dec 14, 1998
Posts: 20276
    ∞

They call it the float test, but he is allowed to swim. As long as he can swim in just one spot - swimming away is not okay. All he has to do is to stay in one place for ten minutes and then put on a life preserver.

On his first try, he jumped in and managed to tread water for a little over two minutes before he had to give up. Granted, if he eased in ... and focused on conserving energy ... I dunno, he might make it to four minutes. It does seem like he has to put a lot of work into staying alive in water. A year ago he swam about half a mile without resting and without floatation stuff. But he didn't have a bunch of street clothes on.
Jeroen T Wenting
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Joined: Apr 21, 2006
Posts: 1847
Originally posted by marc weber:

Yes, water will almost always reject a witch. However, this test is from the dark ages. Nowadays, a simple blood test is used.


yes, ever since it was found out that witches are ducks they just compare a woman's blood with that of a duck.
Takes all the fun out of the witchhunting if you ask me.

No more giant scales, throwing people in rivers with millstones around their necks.

At least the barbequeues have gotten more fancy, replacing the stake with a grill and the tar with orange glazing.


42
Marc Peabody
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If he's wearing shorts underneath the pants and the pants don't have holes, he could make a floatation device out of his pants. The hard part is taking them off while treading. After that, tie off the legs and blow it up like a balloon.


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Peter Rooke
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Joined: Oct 21, 2004
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Just a few things a picked up about swimming: mostly slow strong strokes are more effective. To do this you need to learn to get a feeling for the water.

Hands are the major propulsion (your paddles), so hand position to catch the water is important. Common problems can be wide open fingers, strokes that are too quick (not holding the water). One idea is to try different sculling strokes while standing in shallow water, work out what works and what does not. It is also possible to increase the sensitivity of your hands by clenching your fists before you start.

Kicking is all to do with ankle flexibility. Again a slow steady kick is best.

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Regards Pete
Jim Yingst
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Paul: so, it sounds like he hasn't tried just taking the biggest breath he can and then holding completely still. This would be useful to do, to answer the basic question of whether he is in fact denser than water (with clothes), or not. If he is denser than water, he'll probably have to do one of the following:
  • find lighter clothing
  • make some (hopefully small) movements while floating which propel him upward, to offset the weight/buoyancy imbalance
  • fatten up

  • [Peab]: If he's wearing shorts underneath the pants and the pants don't have holes, he could make a floatation device out of his pants. The hard part is taking them off while treading. After that, tie off the legs and blow it up like a balloon.

    Hey, I remember doing that. As I recall it was easiest to just let myself slowly sink while getting the pants off, then swim back up to the top. Removing pants while kicking is needlessly difficult. Separating the two tasks helps quite a bit. (Sounds like a refactoring discussion.) Of course in a 12-foot pool, letting yourself slowly sink probably just results in being on the bottom. I don't know if that's within the rules or not. But getting the pants off is much easier if you're not overly worried about getting to the surface ASAP.

    By the way, are there rules about shoes? In an in-water survival situation, I'd just lose the shoes first thing. They're extra weight, and they impede the ability to remove the pants, which are useful for flotation as Marc discussed. Try putting the shoes in a bucket of water to see if they float. If they don't, then they're just a liability, and your son should abandon them during the test (if that's allowed).
    [ August 21, 2006: Message edited by: Jim Yingst ]
    paul wheaton
    Trailboss

    Joined: Dec 14, 1998
    Posts: 20276
        ∞

    it sounds like he hasn't tried just taking the biggest breath he can and then holding completely still.

    He has tried this. He sank to the bottom.


    * find lighter clothing
    * make some (hopefully small) movements while floating which propel him upward, to offset the weight/buoyancy imbalance
    * fatten up


    The first two are in the plan for tomorrow morning.

    The second - we do plan on making sure he has a good breakfast so that he will have plenty of fuel for swimming.

    As for the floating pants: he is required to keep his pants on. Although putting ping pong balls in his pockets and pinning them closed has been a tempting idea!
    Bert Bates
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        5
    This is really weird - but here a couple more thoughts:

    - assuming a candidate who is bouyant (which I understand is in question here)- when you come up for breath you'll sink less far (before resurfacing) if you:
    a - lift your head only a small amount
    b - try to stay both relaxed, and as horizontal as possible.

    So the idea here is not to create a "straight arrow" kind of posture every time you come up for a breath. I haven't done this for a while, but I recall if you lifted your head a lot it could take a long time for you to resurface...

    Maybe because of his age, he hasn't grown into his big heavy bones yet?
    paul wheaton
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    Joined: Dec 14, 1998
    Posts: 20276
        ∞

    Dane and I talked this one to death. But with busy schedules, the earliest we could go was at 9am this morning. We get down there only to find out that they don't open until 10am.

    So we go home and come back at 10am. Then they say that float tests are only at 1:30 to 2:30. But the class starts at noon! I carefully explained that we called and were told that float tests can be done anytime on weekdays. "That person did not tell you the truth" "Two different people told us" "They were both wrong."

    @#$%^&*!!!

    "So how do we get a float test done before noon?" Any of the beaches where there is a lifeguard. So we go out the door and there is one of the beaches. No life guard to be found. "We can't seem to find the lifeguard". "Look in the trailer to the left of the life guard perch." As we're knocking on the trailer door, we see a sign that says that the lifeguard will be on duty at 11am.

    The water will be colder. That could make taking the test harder ...

    Dane slowly treaded water for ten minutes and then put on the life preserver. He passed!

    Thanks everybody!
    David O'Meara
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    Congratulations Dane, we was all rootin' for yer!
    Bob Reardon
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    Joined: Jun 01, 2000
    Posts: 160
    Originally posted by marc weber:

    Yes, water will almost always reject a witch. However, this test is from the dark ages. Nowadays, a simple blood test is used.


    I thought they tried to build a bridge out of her.
    Marilyn de Queiroz
    Sheriff

    Joined: Jul 22, 2000
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      10
    Originally posted by Jim Yingst:
    Well, maybe. For what it's worth, the depth is irrelevant here; the density of water doesn't change perceptibly with depth.


    I'm sure you're correct, but...
    it has always been easier for me to stay afloat in water 12 feet deep as opposed to water only 3 feet deep.
    Jim Yingst
    Wanderer
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    Ys, but isn't that because in water 3 feet deep most of us would find it easier to simply... well... stand up? In 3-ft water it takes extra effort to hold your arms and legs up enough to avoid touching the bottom, if for some reason that's what you want to do. No one would have any reason to do this in a survival situation. In my previous discussion I assumed that the water was deep enough that simply standing up was not an option. If it were, the float test would be pretty much unnecessary, would it not?
    [ August 29, 2006: Message edited by: Jim Yingst ]
    Richard Green
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    when i saw the title "float test" and the author name "paul wheaton", i thought "hmm this thread gonna talk about probably a test class on floating point decimals, afterall he is a java guy" ...


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    paul wheaton
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        ∞

    Dane had a great time sailing. His favorite part was that they were encouraged to capsize their boats a lot. And then they were encouraged to capsize the boats of the other students.

    So he learned a lot about sailing. And, maybe about pirating.
     
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