A question of lifting bodies underwater

[Dr Quest]

If I have two rubber coated kevlar balls, one is filled with air and the other has a gas like helium in it, if submerged underwater, would the ball with helium be harder to keep underwater than the air filled ball would be, or would they be equal in their buoyancy?
Also is helium easier to compress than air, I would imagine it would be but I don't have any schooling in this field.
Thanks for the site, and any answers to my questions.

 

[russ_watters]

The way the definition of buoyancy works, the buoyancy is the same - what is different is the weight of the two gas-filled spheres. Since the one filled with helium is lighter, the net force required to keep it submerged is higher.

 

[lpfr]

Russ_watters is right. But you cannot feel the difference. You must measure the two lifting forces with a very precise device. The difference in lift is about 0.1%.

 

[Dr Quest]

Thanks for the info!