Bouyancy: Warm water vs Cold water

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Is there a chart somewhere that will indicate the amount of weight needed for salt water dives?

Yes there is: PADI Adventures in Diving manual p. 213. Roughly 4% of body weight in addidional weight over fresh water.
 
If the water gets cold enough you can eliminate weights all together.:wink:

Gary D.
Might be a tad hard to descend tho, regardless of how much weight you use :p
 
Might be a tad hard to descend tho, regardless of how much weight you use :p

:wink:

Gary D.
 
Just for disscussion....If you where inside say a big steel tube (think 10,000 tons) instead of neoprene the water temp and salinity affect bounancy.
 
Just for disscussion....If you where inside say a big steel tube (think 10,000 tons) instead of neoprene the water temp and salinity affect bounancy.
The water temp would also affect the size of the steel tube too, alas the ammount of water you displace..
 
Interesting point.

Any physicists online?

Does anybody know the weight difference between between 33fsw at 35 degrees f and 33fsw at 80 degrees f?
 
Does anybody know the weight difference between between 33fsw at 35 degrees f and 33fsw at 80 degrees f?
In post #4, Blackwood says 0.43% change from 33.8 to 86F at 1ata. As you can see from the chart below, the change with temp is about the same at both 1ata and 25ata, so the answer to your question is also around 0.4%.

The chart also shows that going from 1ata to 25ata (800' depth) only changes the density of water about 0.1%.

water-density-temperature-pressure_2.png
 
Really cold water [-]weighs less[/-],,,,,,,,,,,ice floats.

*is less dense*

Yes, at some point (about 4°C at 1 ATA as seen on the graph posted above by Charlie) the density of water starts to decrease with temperature. So ice will float on cold water. But not warm water (it will float on water that's 5°C, for example, but not on water that's 10°C).
 
*is less dense*

Yes, at some point (about 4°C at 1 ATA as seen on the graph posted above by Charlie) the density of water starts to decrease with temperature. So ice will float on cold water. But not warm water (it will float on water that's 5°C, for example, but not on water that's 10°C).


Ice floats on any temperature water. Ice is less dense than water because it expands when it freezes.
 
https://www.shearwater.com/products/peregrine/

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