Andy -

Someone suggested closing the inlet to your ballast tank, and that got me
thinking.  If you have air in the ballast tank, and the tank is open to
the outside water, then whenever you dive, the air will be compressed and
you will take on more ballast water.

Is this a problem?  Do you need an active ballasting system that will
constantly adjust the ballast level?  Would it be easier to close some
intake valves and ensure that once you reach neutral bouyancy, you stay
there?

Don

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