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Re: [PSUBS-MAILIST] Hard / soft ballast tanks.

Bill,
 
   To make a "soft" tank into a "hard" tank, do I simply need to install a valve to let in the water as opposed to just an open flood hole ?  This valve, of course, would keep the water from coming in while the sub gains depth (pressure).
 
Myles.
----- Original Message -----
From: Akins
Sent: Saturday, October 29, 2005 1:54 PM
Subject: Re: [PSUBS-MAILIST] Hard / soft ballast tanks.

Ah yes! Brian is right Myles. I totally forgot about the compression of the air by the water at depth in the open bottom ballast tanks. That is another reason to use non open to the water hard ballast trim tanks
 
to adjust the attitude and neutral buoyancy of the sub at depth.
 
Bill.
 
 
----- Original Message -----
From: Brian Cox
Sent: Saturday, October 29, 2005 9:20 AM
Subject: Re: [PSUBS-MAILIST] Hard / soft ballast tanks.

The reason is that as the air gets compressed ( in a soft ballast) as you descend the volume shrinks and you have less lift, making you sink faster.  This gets you into a situation where you are constantly readjusting to maintain a steady accent or descent.  I believe this is all in the busby book which can be bought on the psubs web store.
 
Thank you
 
Brian