Waterbuoy

[michaelh]

Why don't you try a simple explanation /forums/images/graemlins/smile.gif

where Mobject is the true (vacuum) mass of the object, whereas Pobject and Pfluid are the average densities of the object and the surrounding fluid, respectively.

 

[Gludy]

But that simple formulae is what i have been stating/
Masss is weight on earth. And the SG of water = 1
So all it states is the weight of the object = 1 - (sg of obect)/1)

Its the same thing but kust looks more impressive!!!! /forums/images/graemlins/smile.gif

 

[Gludy]

Re: Waterbuoy & Mushy peas

I could not find a can of beans so I used a can of mushy peas.
It weighed 370 gms and had a volume of 342 cc so its had an SG of 1.08

Hence assuming its the same as beans - an reasonable assumption 1 kilo of these in water weigh 80 grams.
So no wonder waterbuoy can lift 900 gms worth - it had to pull less than 80 grams!!!!!

I think this great mushy pea experiment is conclusive!!!!!

It also has the side effect of me learning the SG of a tin of mushy peas for the first time in my life .... i never knew it before!!!

/forums/images/graemlins/laugh.gif

 

[benjenbav]

Re: Waterbuoy & Mushy peas

If we're all happy with Archimedes' principle now, could I just add that I thought the whole thing a bit rubbish because the only use I could ever imagine for it is to float a set of keys.

I personally wouldn't bother fixing this gizmo on a cellphone or a camera which would probably be ruined by the immersion anyway and, if I drop a can of beans over the side (or even a can of mushy peas) I'll just try to make do without.

So, if it's a device to float your keys up to the surface why not show it doing just that?

 

[Chris_d]

This all sounds a bit complicated aren't you forgeting some basic physics, all the Waterbouy has to do is inflate and displace more than 1kg of water. So if the Waterbouy inflates to a volume of more than 1000cc's it will lift 1kg, eventualy.
A 1kg steel weight would be lifted, yes it is more dense but it displaces less water so it will be lifted.

 

[MapisM]

Re: Waterbuoy & Mushy peas

[ QUOTE ]
it's a device to float your keys up to the surface

[/ QUOTE ]Darn, I was considering fitting one of them to both my 100 lbs anchors, just in case I'd drop them by mistake...
...do you really mean it won't work?
/forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif

 

[Gludy]

Chrus
Sorry - to put is simply you are wrong. Your physics do not apply.

Even IF the waterbuoy managed to inflate to 1000cc - thus generating one kilo of lift you would still have to deduct its own negative buoyancy to see what is left for lift to be used on the item it is lifting.
it has a gas cyliner. a battery, a light, a baloon and plastic.

Secondly
"A 1kg steel weight would be lifted, yes it is more dense but it displaces less water so it will be lifted. "
Wrong.
Because it displaces less water it has less buoyancy and so needs more lift to get it to the surface..

Again the 1 kg can of mushy peas needs about 80 grams of lif to get it to the surface. 1 kilo of steel needs about 850 grams to get it to the surfact - some ten times more required lift than the mishy peas yet both weigh the same in air.

I hope the penny drops. /forums/images/graemlins/smile.gif

 

[fisherman]

Re: Waterbuoy & Mushy peas

I got a Boxit for my phone, it floats (as long as the phone is less than a kg)

http://www.porta-charge.co.uk/brand021_Boxit.html

 

[Gludy]

Re: Waterbuoy & Mushy peas

[ QUOTE ]
So, if it's a device to float your keys up to the surface why not show it doing just that?


[/ QUOTE ]
Exactly - only it costs £13 and you can buy one to do that for less than £4.

 

[Gludy]

Re: Waterbuoy & Mushy peas

The boxit simply increases the overall volume of the phone so that it has positive buoyancy with an SG of less than 1 - its that simple. Its how boats float.
However if you filled your boxit with the phone and water - it would sink.

This has no bearing on the waterbuoy issue that I can see. /forums/images/graemlins/smile.gif

 

[Chris_d]

[ QUOTE ]
Again the 1 kg can of mushy peas needs about 80 grams of lif to get it to the surface. 1 kilo of steel needs about 850 grams to get it to the surfact - some ten times more required lift than the mishy peas yet both weigh the same in air.


[/ QUOTE ]

I think you've muddled yourself, the above is mushy peash, all you have to do is displace more than the weight in water of what you want to lift. I have seen Raise the Titanic you know /forums/images/graemlins/grin.gif

 

[Planty]

Re: Waterbuoy & Mushy peas

Hi Paul,

Now we've got everyone to agree the water buoy is only really any good for your keys, can we please get back to red diesel and traders ?? You have to kerb these tendencies to get diverted from the real issues here! Only joking mate, how the devil are you by the way !! Paul

ps, that Archimedes bloke, didn't he have something to do with Baths, now I do know about them ! Who did he work for, was it Armitage Shanks or Ideal Standard??

 

[adey]

What depth would your keys sink to in the ten seconds that the device takes to inflate?
In actual fact the 1Kg weight device took over twenty seconds.
Wouldn't the greater pressure make it less effective?
If anybody missed it you can see the video on the BBC website.

Who's going to send the link to this thread to Peter Jones and Theo Paphitis /forums/images/graemlins/grin.gif

 

[Gludy]

Chris
Sorry mate but whilst what you say is correct - 'you have to displace more than the weight of water you want to lift' You fail to apply it to the ikg can of mushy peas sitting on the bottom already displacing a lot of water and the one kilo of steel alongside it displacing a lot less water and so needing the baloon, in this case, to be ten times bigger.

The whole point is that to displace the water you have to have a high volume hence low sg for a given weight. Because steel displaces less water it needs more power to lift it than a can opf mushy peas .... surely you can see that?

 

[Gludy]

Re: Waterbuoy & Mushy peas

"Now we've got everyone to agree the water buoy is only really any good for your keys, can we please get back to red diesel and traders ?? You have to kerb these tendencies to get diverted from the real issues here! Only joking mate, how the devil are you by the way !! "


There is still a lot going on in my disastrous boating life:-#
1. Down to the last £20k worth of post dated cheques from Trader.
2. Have just issues legal proceedings for breach of contract against the UK Marlow agent.

So things are pretty normal! Hence its rather nice to chat about mushy peas. /forums/images/graemlins/smile.gif

 

[Renegade_Master]

Neale one word of warning dont do what our cleaning staff have done now on several occasions, they have unlocked the sliding patio door on our flybridge vessels to clean the boat inside. When finished they go outside to clean and hose down the boat and yes you've guessed it,.........left the keys and pop up ring in the door key hole and hey presto its gone off /forums/images/graemlins/smile.gif Its started getting expensive

 

[Planty]

Re: Waterbuoy & Mushy peas

Blimey, sorry to hear that, forgive me I've not been around much and as you may have seen, we sold Damn as we had a really good offer last month. Still got the rest of the fleet though, Honda Racer etc, keeps me interested!

Where would I find the low down on the problems with Marlow?? P

 

[tazzle]

My experiences pottering around the south and east coasts suggest that the quality of the mud could be an important factor in whether the device raises dropped keys to the surface. Rye mud, for example, is fine grained and far less glutinous than that found in Newhaven or Shoreham. Newhaven mud, in particular, has a grip not far short of Araldite. Medway mud is very 'sucky' but since I haven't dropped anything valuable overboard yet, I can't report definitively on the release-force required.

I propose the adoption of a new Standard Unit, the Cack. One Cack shall be the force required in Newtons to raise a Standard Key Bunch dropped through 1m of seawater at STP into a uniformly compacted container of Newhaven Mud. When the lifting force in Cacks is added to the force required by the balloon to lift the keys through the water, the true size of the balloon required can be determined.

 

[Gludy]

Re: Waterbuoy & Mushy peas

Planty
There really is no low down anywhere on the Marlow. Coming to a court room near you soon as they say. /forums/images/graemlins/smile.gif
When its over I amy well make an announcement.

 

[Gludy]

I very much like your scientific appraoch to this problem.
Waterbuoys arer actually inded for the chack handed as you say so we rerally should adopt your system - however the shape of the object itself will have a major influence on the defining force for one cack. For example a I kg plate sitting in some cacky mud will have a higher cack factor than a simple can of mushy peas.
For this reason I suggest we adpot the standard mobile phone as the object to measure caxck force with on the grounds that such objects are bu no means any strnager to cackly mud ... unless you have a betters suggestion of course?