Torque in water

[m441]

Density of water change with radius. Gas inside sphere can be at very low pressure, so no interaction with water. Spheres of gas are attached together. Spheres of gas can turn around red point. Dot lines are only there for watch what water interact with other. How the torque in that system can be to 0 ?

[Dan B-Yallay]

I am not sure what do you mean by "torque" - did you translate it from French? If torque $=$ Tourbillon - it might depend.
If torque $=$Moment d'une force, then it should be there. I am not, however, a specialist in this area, so you might need to wait until one comes.

By the way, your picture is not complete because there are two different possible ways to rotate, depending on the construction of the joint. See my picture.