Question regarding Bouyancy in Water

[Ralith]

This has been bugging me for a bit. Take two, identical, rigid containers. Fill one with helium at the level in say... a balloon? Then take the other one, and suck all the air out. Take them to the bottom of a container of water- Which will go up quicker?

 

[mgb_phys]

Assuming the vacuum one doesn't crush - it will weigh slightly less than the helium one and so rise faster.
If you could make the envolope strong enough, 'nothing' is the best thing to fill an airship with.

 

[Ralith]

Thanks. Thought so, but wasn't sure.