Water as weight rather than lead?
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Okay, this is a serious misuse of my degree in oceanography, but there is actually a way you can make this work. Well kind of...but there are certain drawbacks.... 
Suppose you are diving in average seawater with a salinity of 35 psu which has a density of around 1025 kg/cubic meter (at 1 atm and about 20 deg C). The trick is that saltier water is actually more dense as I think most divers are aware.
So suppose your water weights had a salinity of say 70 psu. That would give a density of 1052 kg/m3. This is a difference of 27 kg/m3. So if you needed 9 kg (ie about 88.2 Newtons of downward buoyant force), you would have to carry about 1/3 of a cubic meter (about 333 liters) of 70 psu water with a total mass of nearly 351 kg.
I apologize to those that don't like metric units.
It is amazing the things I will do to avoid working on my dissertation....
Suppose you are diving in average seawater with a salinity of 35 psu which has a density of around 1025 kg/cubic meter (at 1 atm and about 20 deg C). The trick is that saltier water is actually more dense as I think most divers are aware.
So suppose your water weights had a salinity of say 70 psu. That would give a density of 1052 kg/m3. This is a difference of 27 kg/m3. So if you needed 9 kg (ie about 88.2 Newtons of downward buoyant force), you would have to carry about 1/3 of a cubic meter (about 333 liters) of 70 psu water with a total mass of nearly 351 kg.
I apologize to those that don't like metric units.
It is amazing the things I will do to avoid working on my dissertation....
Afraid_of_Fish
Guest
H2Andy:
You just opened up a whole new can of worms for dweeb to call you on lolz.
glbirch
Contributor
I think you'd get the same result as the temperature change comment. You would become more bouyant in relation to the high salt water immediately around you, and start rising (especially since you just dumped all that heavy saltH2Andy:
) but that bubble of high salt water would be less bouyant than the ocean around it, and start to sink.
Afraid_of_Fish
Guest
glbirch:I think you'd get the same result as the temperature change comment. You would become more bouyant in relation to the high salt water immediately around you, and start rising (especially since you just dumped all that heavy salt
He was serious?
OP
H2Andy
Contributor
Afraid_of_Fish:
i know the importance of being earnest
glbirch:
ok.. well... then the trick is to carry a buttload of salt with
you, and increase the salinity of a few square miles of ocean.
what we need to do is invent concentrated salt, so that
a teaspoon is the equivalent of six tons of regular salt.
then we're home free
H2Andy:
Actually, Andy, your original proposal of using water as weight would work as long as that water came from the Dead Sea.
I have a bottle of it at home I collected a couple of years ago, and as it is so full of salt that it has the consistancy of baby oil, its density FAR outweighs that of even sea water.
I figure that it is aproximately 40-60% salt, therefore a liter weighs about 1.5 kg. If you are wearing a drysuit and need 10 Kg of weight you would need 20 litres of water, so that would be just over 5 gallons, with aproximately 6% more if you are planning to dive in the ocean rather than in fresh water.
Andy, you need a five gallon water bottle of dead sea water and you can prove that Dweeb is a pompus ***.
H2Andy:
I just love science.
glbirch
Contributor
Wait, now I'm confused. If you're being Earnest, then who is Earnest being?H2Andy:i know the importance of being earnest
glbirch:
ok.. well... then the trick is to carry a buttload of salt with
you, and increase the salinity of a few square miles of ocean.
what we need to do is invent concentrated salt, so that
a teaspoon is the equivalent of six tons of regular salt.
then we're home free
I don't like that concentrated salt idea. If you accidently dumped a load of that and brought the salinity up too much it might kill off a bunch of sponges. Then we'd have to go back to the question of what happens to the ocean without the sponges.
Will CaCl work? I hear they dumped a barge load of it in the Great Lakes.
glbirch
Contributor
Isn't that the anti-icing stuff? Sounds like a scuba-board plot to lengthen the dive season by keeping the lakes from freezing over...NetDoc:Will CaCl work? I hear they dumped a barge load of it in the Great Lakes.
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