[PSUBS-MAILIST] One way Tank

[MerlinSub@t-online.de]

Jon - this is in general the description of the simplest type of hard ballast tank. A one way tank. Let water under pressure in by a small pipe and valve. Tank must be not pressure tight. can be a softbag inside the sub. There is no way to get the water out under pressure - but this is okay if the pilot is carefully and get the boat bouyancy on the first shoot.  Very simple system: Hard ball valve, pipe and softback should work. It prevent that you have to surface again and cry for more lead... 

Emile and I training many times on Peppers to us the real hard tank there in this one way mode - just to save the compressd air to blow the water out to many times which was "overshoot" and cost you air - and at the end of the day dive time. 

regards Carsten 


"Jon Wallace" <jon@psubs.org> schrieb:
> 
> I found an article written by Dr. Sylvia Earle describing "Deep Rover" and
> how it works.  The article includes the following description of ballast
> usage which I consider to be very straightforward and easy to understand.
> I'm going to add this to the webforum as well.  The full article can be
> found at:
> http://www.usc.edu/org/cosee-west/MidwaterRealm/14SSEbackground.pdf
> 
> 
> ## START QUOTED MATERIAL
> In order to regulate its position up and down in the water and to remain at
> a certain depth without rising or sinking, DeepWorker uses two forms of
> ballast systems??soft? ballast and ?hard? ballast.  Many submersibles use
> what is called a ?soft? ballast system in which compressed air is released
> into an external tank to increase the craft?s buoyancy and bring it back to
> the surface. At deep depths, air becomes so compressed by water pressure
> that it can take an entire tank to lift the sub off the bottom. In these
> systems, such as the Deep-Rover submersible, pilots must limit their up and
> down movements at depth to conserve air for the final ascent.
> 
> DeepWorker uses soft ballast together with another ballast system known as
> ?hard? ballast. In the hard ballast system, colored water is contained
> within an enclosed small bladder outside the sub. After the pilot dumps all
> the air from the soft ballast tank in order to lower the sub below the
> surface, the sub remains slightly buoyant. To sink, the pilot opens a valve
> to allow a small amount of the colored water into the sub, which adds
> weight. The water begins to fill a tank in the pilot?s seat, and the sub
> descends.  When the sub is neutrally buoyant (neither sinking nor rising),
> the pilot shuts off the valve. This ingenious design allows the pilot to
> remain neutrally buoyant at any depth. Pilots can tell when they are
> neutrally buoyant by looking at minute particles drifting outside in the
> water column.  When the sub hangs motionless in relation to the tiny
> organisms and debris that make up the ?marine snow,? the sub is neutrally
> buoyant.
> ##END OF QUOTED MATERIAL
> 
> 
> 
> 
> 
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