Dave Doe wrote:
You're just being a pedant aren't you.


No, I am less interested in seeming clever, and playing
semantic games, than I am with simple facts and the physics
that make things work.

What makes a diver sink? - the BCD? Or the weight belt?


Totally different picture. The BCD is a variable volume
device. When the diver inflates it, he is increasing his
displaced volume. That would be similar to attaching a
helium balloon to a sailboat mast for added stability.


The lead or DU is put in the sub at manufacture time, to ensure it is
"heavier than water" (it's overall desnity is greater than water).


Then why does it float when the diving ballast tanks are empty?

Otherwise.. yes they *would* have to find a special place to scoop up
lead, DU, rocks - whatever - to submerge - as their bouyancy ballast
tanks would be ineffective with water in them. You'd have a positive
bouyancy vessel. You can put as much water in 'em as you like - it'd
never sink.


Really? The fact that they're made of steel, and are
ostentatiously lacking in styrofoam, would make it seem
likely otherwise.

Fact- water ballast works just fine.

Fact- any physics used to try & pretend it doesn't must be
false... just like any physics explaining why airplanes
can't really fly... or is that going to be your next hobby?

I do have one suggestion for you.... look up 'metacentric
height' and ponder the relationship of the ceneter of
gravity to the center of bouyancy. It's easier than the
sound of one hand clapping.

DSK