Waterbuoy

[Gludy]

Neale
Asj yourself why they used such a large box that only weighted 1 kg?
The answer is to give it a low density and hence reduce the lifting force needed!!!!
You are not accepting Archimedes principle!!!!!!
These tests were done well over 1000 years ago!!!!!!

Your weight will have only about 1/6th of the volume of the box and so require 6 water buoys!!!!!!

This is so, so simple and yet you are refusing to see the facts!!!!! Amazing. /forums/images/graemlins/laugh.gif

 

[rickp]

[ QUOTE ]
Rick the ballon has to be a litre underwater and that depnds on the amount of gas pushed into it. Underwtaer the baloon size was nowhere nerar a litre.

Ia m not ignoring the point - I am stating simple facts, nio opinions and am amused and amazed at the resistance to these simple facts.

[/ QUOTE ]

Sorry Paul, don't dispute the science, but you are stating an opinion of the balloon size. Unless you have facts about its size and the capacity of the retail model which you're not sharing.

Rick

 

[Gludy]

In 10 metres of water the atmospheric pressure is twice that at the surface and so any balloon would be about half the size.

Every 10 metres of water depth adds an atmosphere.

The gas cylinder needed to blow up the balloon gets bigger and bigger with depth.

If you saw how small the baloon was when it starated to lift the i kg weight under a foot or so of water - it only just managed it.
I do not think it wouild have even managed that at 10 feet.

There is a reason they used such a large box.

Straight question - do you accept that much more lifting force is required to lift a 1 kg lunmp of lead (sg say 10) compared to a i kg lump of platic with an sg of 1.05?

In pracitce you would need 20 times the lifting power to lift the lead!!!! Yet both are the same weight in air.

 

[Gludy]

I never guessed the ballon size anywhere.
That was my reply to that question whn im was asked about it. others guessed the size at about 1 litre.

What I can observe is that the limit of the lifting power was based on a large low density box. I know that a i kg lump of steek is say about 1/6th of that size and so would require about 6 times the lifting force of the box they used. It is therefore a no branier to know that the baloon couild not lift a i kg weighing scale weight.
Take a look at the size of the box and make a stab at the SG of it.
That is my evidence.

It is also an ireftuable fact that claiming that they way they6 mixed up lifting power with weight is nor science and is misleading.

The baloon can just lift a 1 kg box of that size but as that size is reduced it cannot lift it. A box half the size requires about twice the lifting power even though it weighs the same.

I saw the size of the ballon under the water and it was IMHO no tnear a litre but I do not need to rely on that to support my argument.

 

[neale]

I am not sure you have read my posts. I have agreed to retest them, which means you have made statements that I believe may have some substance.

I have also said that I think the waterbouy will protect the "typical" items that you may wish to protect. Even if they fail to lift 1kg of lead, I still think they would protect most stuff, including a bunch of keys far bigger than a standard cork keyring.

 

[MapisM]

Huh? Maybe I wasn't clear in my previous post, but I was actually supporting your view.
What sounded unreal to me is not your explanation, but claims like the one you quoted, or like '1 litre of air lifts 1kg of load, whatever its shape", etc.
And I was referring to these gentlemen when I wondered why they're not scared by using a boat, considering its weight...

 

[Phoenix of Hamble]

The moral of the story... buy big lightweight keys!

 

[Gludy]

We are getting somewhere ... I detect movement /forums/images/graemlins/smile.gif
[ QUOTE ]
I am not sure you have read my posts. I have agreed to retest them, which means you have made statements that I believe may have some substance.

[/ QUOTE ]
Its not me that has the substance - its Archimedes!!!!!

Do you accept tha the uplift on any item submerged in water equates to the volume of water displaced? So if you displace 1000 cc you have an uplift of 1 kg?
This is how a boat floats by the way.

Now that 1 kg box was large – if it was 900 cc (and it looks at least that) then it would have uplift of 900 grams and so only require an force of 100 gms to lift it.

A I kg lump of steel would be a fraction of the size with a fraction of the uplift and would require maybe about 6 waterbuoys to lift it.

Hence the way the experiment was presented was totally misleading – agreed?

Far better to state the weight of a typical bunch of keys that the system could lift. That would not be misleading but they did not show a big bunch of keys just two or three!!!!

The USA one sells for less than 1/3rd of the price and clearly states its lifting force.
All I am saying is that the 1 kg lifts would only apply to large objects like that box which have to be low density to only weight 1 kg and very few people are going to attach waterbuoys to such large objects but they may be misled into attaching a large bunch of keys.
As it requires the destruction of the £13 item to test them, very few are going to do that and may think that it can lift a 500gm bunch of keys – they would be very wrong and would one day maybe lose those keys they thought were protected!
[ QUOTE ]

I have also said that I think the waterbouy will protect the "typical" items that you may wish to protect. Even if they fail to lift 1kg of lead, I still think they would protect most stuff, including a bunch of keys far bigger than a standard cork keyring.

[/ QUOTE ]
But is it not far better to know what typical weight they can lift of the typical item eg a bunch of keys?

 

[neale]

[ QUOTE ]
But is it not far better to know what typical weight they can lift of the typical item eg a bunch of keys?

[/ QUOTE ]

Ok I am sure that I have enough keys at home to make up a keyring that will come in at around 1kg. I have spoken to them and they are going to send me a couple as soon as the next batch arrives. This should be this side of xmas. Watch this space.

 

[gjgm]

think I can see Gludy's point on some of this. If you took a sealed tupperware box, it would float on the surface. If you then put a number of coins,say, in it, maybe it would float half submerged. If you could then fill it with water unitl it just started to sink, you would only need a small bouyancy force to refloat it. If you took it out and weighed it, it might be quite heavy- but just how heavy isnt relevant. Then take a lump of metal of the same weight.. it wont just float/sink.. it will sink very fast, and you ll need more bouyancy to lift that. But the weight of the two is the same.

 

[fisherman]

I reckon from the size of the hand, the balloons are about 12cm diameter. That's a lift of 904 gms, but the ballon is half submerged, so about 450gms max is being lifted.

You were all shouting so much you didn't notice my wrong calculation earlier. Apologies.

 

[Gludy]

gjgm
Spot on and its called Archimedes principle.

 

[Gludy]

Neale
If you are in contact with them ask them what the lifting force os their product is - they should know what it is.
Also ask for the outside dimensions of that 1 kg box because from that I can calculate what the lifting force is.
Seems very simple for them to tell us this.

 

[gjgm]

eureeka !!!

 

[Gludy]

I just decided to take a look at their site in more detail and I am frankly concerned at their claims.

They claim it can lift UP TO 1 kg = that is true but only if the things has such a low density that it cannot fit in any pocket to begin with!
Nowhere can I find that they give the actual force it can apply - the actual lifting force.

The products has a light, gas cylinder etc so any balloon has to not only overcome any negative buoyancy ot itself but also the cylinder, LED light and plastic housing.

I am frankly very concerned how people will use the information on this product and I do, having gone through the site, consider it very misleading. It may lead people into thinking it can lift a 1 kg weight from the bottom.

My public question to Waterbouy (They have no telpehone number on their site) is for them to tell us what the actual lifting force is at say 10 foot or any other depth they choose. They must know this.

 

[KevB]

[ QUOTE ]
Now that 1 kg box was large – if it was 900 cc (and it looks at least that) then it would have uplift of 900 grams and so only require an force of 100 gms to lift it.

[/ QUOTE ]

I've got a headache now. surely we are talking about the size of the balloon required to keep the flubber afloat and not the buoyancy properties of the object itself. Yes, the larger the object the more buoyant it will be for a given flubber because of the volume of water it's displacing for it's flubber but....... if a 1kg flubber was tied to a balloon which was of a size that if submerged would displace more flubber in water than the flubber of the object, the balloon would stop the object from sinking.

If 1 litre of water flubs 1kg and 1 litre equals 1000cc's in volume, the balloon would only need to contain 1 litre of air a surface pressure to stop the flubber from sinking and would need to be 1000cc in volume at a given depth to raise the flubber. So to my thinking 1 litre of air in a balloon a surface pressure will always stop a 1kg flubber from sinking regardless of it's physical size or density? Also you have to subtract the flubber of the water displaced by the object from the objects flubber to give the objects true flubber in water.

I understand that the amount of water displaced by 1000cc's of air at surface pressure in a balloon will be different at different depths thus displacing less water which will flubber less giving less lift a given depth.

Now all the above may be bollox but I'm having trouble seeing where it is. It seems so simple that I think I must be missing something?

Please help /forums/images/graemlins/confused.gif

 

[Planty]

Don't know about all this maths, 'cos I'm thick, and can't comment on guys talent for invention or otherwise, but what does take real talent is to get all them "weight" words in near perfect alignment in your post!!

Paul

 

[KevB]

The reply only took a couple of minutes to type, the other hour was getting the weights in line /forums/images/graemlins/smile.gif

 

[KevB]

Does it read better now?

 

[Gludy]

What matters as regards the submerged object is it weight IN WATER.

To get this you deduct the weight of the volume of water it displaces from the objects weight when out of water.

So a can of beans weighing 1 kg would probably displace 900 cc of water and only weigh 100 grams in water.
A steel weight of 1 kg would displace 150 cc and so weigh 850 grams in water.

Now any object attached to these things to lift them has to overcome the weight in water ( am am ignoring shape and fluid resistance etc).

As you can see from above the can of beans requires only 100 grams of lifting force whereas the same weight of steel requires 8.5 times that lifting force!

So now take a look at the lifting object - Waterbuoy.

This has the weight of the gas cylinder, plasticm baloonm, light etc to overcome out of the buoyancy of the baloon before we can use any of the buoyancy to lift another object. These are unkown to us but what we do know is that it would require to displace more than 1000 cc of water to overcome a downward force of 1 kg plus its own downward force.

The reason the TV demo did not use a 1 kg scale weight was because that would probably take 6 times the force to lift compared to the box.

To properly measure Waterbuoy - simple hold an inflated waterbuoy under the surface on a spring balance and measure the force it applies to the spring balance.

I already know it cannot lift a proper 1 kg weight because I have seen it just , and I mean just lift the large box.

In practice I doubt, and this isa guess, if water buoy can lift more than 200 grams of keys from the bottom in 10 m of water. Maybe not even that.

If I knew the dimensions of the wooden box they used - I could tell you more exacly.

My only interest in this is to stop folks wasting money and losing keys etc. Waterbuoy can solve this by providing the true lifting force. Its that simple and I promise it will not be a kilo simply because the volume of that large box has to be dedcuted from its weight to get the lifting force it just managed on TV.