Michael Levy wrote:

>> Try a Current dive with a buddy of exactly the same shape and mass. Have
>> him sit in the water vertically- and you lay horizontally - stay far
>> enough apart so the current does not change due to the drag from one of
>> you affecting the flow to the other-- who will go faster in the same
>> exact current ?

>Seen every day in Cozumel with near vertical newbies drifting away from the
>group leader.

Not hardly.  For starters, where are you going to find two divers of exactly
the same shape and mass?  If you could find two such divers and assuming a
common current, ie one's not in a faster moving portion of the water column
than the other, the one that offers the most resistance to the flow, the
vertical diver, will accelerate more quickly, moving away from the
horizontal diver.  When both divers have reaches their maximum current
enduced velocity, equal to the velocity of the current itself, they will
move at the same speed, remaining a constant distance.

In order to test this with two divers in sight of one another, they need to
begin as one, holding hands, for example.  Once their speed has stabilized,
release hands.  All else being equal, i.e. all factors other than current
eliminated, the two divers will remain in the same position relative to one
another.  The problem is, of course, that periods where the current is the
same in for two divers will be very short and the period during which both
of them can resist movments that will generate thrust (pretty much any
movement) are even shorter.

A better test would be two inanimate objects, adjusted to neutral buoyancy,
released in current, in open water, where the current is most likely to stay
the same the longest.  They should move together until some outside force,
like alteration in currents, affects one of them without affecting the other
in the same way.

Lee