Water and gravity: look at this video

[sm0ky2]

Real-world example:


Sink a raft in the ocean


You will need to go down several hundred feet before it
irretrievably collapses under the pressure of the ocean.
Fresh water is less dense so it would take an even greater depth


YES there is a change in pressure by depth
And we can calculate exactly how much this changes.


Doesnt affect the action of the Cartesian Diver until very great
heights are reached within the water column.


The ranges we would use for any sort of application,
fall well within normal operating conditions

[MT]

YES there is a change in pressure by depth
And we can calculate exactly how much this changes.

Doesnt affect the action of the Cartesian Diver until very great
heights are reached within the water column.

The ranges we would use for any sort of application,
fall well within normal operating conditions

Was searching a bit diving websites and yes it should not have much impact for devices with practical dimensions like 1-2 meters of height. According to Boyle's law, doubling pressure halves gas volume at constant temp. And pressure at water increases slowly, 1/10th of bar per meter.
 
So a diver starting at surface with ~1bar pressure and 4liters of ideal gas volume would need to go 10meters deep to see its volume halved. At 30meters it would be just 1 liter.

That shrinking works in our advantage when diver is sinking as volume is lower and is thus even less buoyant and similarly during rising it works in our disadvantage.

[MT]

Question, have you or maybe somebody else already did some or even complete energy calculations of this design on a concrete example?


I mean first initial energy of whole system with diver at top. Then:
1. energy needed to compress
2. work bober can produce on its way down
3. energy that can be retrieved during decompression of whole system with diver down
4. work bober can do on its way up.


For example 1m3 aquarium, 10kg diver with 12 liter of ideal gas.

[sm0ky2]

I have not made any sort of prototype

[sm0ky2]

Here is the basic physics.
Displacement of the motive mechanics will need to be accounted for


https://physics.anu.edu.au/engage/outreach/_files/Cartesian%20Divers.pdf


Here is a more in-depth analysis
Which shows irreversible sinking as a factor of bobber diameter.


https://iypt.ru/wp-content/uploads/2020/10/A-lot-of-good-physics-in-the-Cartesian-diver.pdf