Kurt:

I refer you to my entry on 7/18/02 @ 03:17.......

Upon diving the boat, in response to two blasts on the diving alarm (Klaxon) I, as chief-of-the-watch, I observe the hull-opening control panel ("Xmas tree") until all indicators are green. I tell the diving oficer "green board" and he orders "pressure
in the boat" whereas I order the air-manifold operator to "bleed air in the boat."
This is done momentarily to check for a "tight boat" and I observe the altimeter to check for a drop in pressure. Then I report "boat is tight"

All this time, the Negative tank flood valve has been opened to sea, and before the boat reaches its ordered depth, I order the air manifold operator to "Blow Negative to the mark" and raise my open hand; when the Negative tank liquidometer (guage)
needle approaches 8,000#, I shut my hand into a fist and the manifold operator secures the blow, and I shut the Negative tank flood valve. Any discrepancies in the
contents of Negative can be handled by the trim manifold operator later in the dive on orders of the diving officer.

3000 psi is used to blow negative normally, however, it can be blown slowly using
the 225# air system or using the trim pump, 'cause Negative is a special variable ballast tank. The 3000# air blown into the Negative tank is reduced by normal expansion.

Now we've got additional air in the boat....

Capacity of Negative tank is 7.1 tons ( 15,000 #) of seawater. The volume of the boat, (with all watertight doors open or "on the latch" is 35,448 cu. ft. I blow out around 8,000# of seawater, leaving about half of this small tank with air pressure from the blow and I vent it in the boat, there's little danger of anyone getting the bends when the boat surfaces.

There are ways to vent this air in the boat. Come to 58' and snorkle on one engine,
or just crack the upper conning tower hatch, and allow the air to bleed out slowly.
This is a good method of clearing loose "trash" from the conning tower and cooling
the conning tower off in a hurry.

While standing watches at the helm (in the conning tower) I've assisted the
quartermaster in doing this several times.

We never blew Negative tank dry......

Have you opened the website I recommended on 7/18/02?

Later.

ROBERT M.