Re: [PSUBS-MAILIST] Re: Variable Ballast Calculations, Bill

[Carsten Standfuss <Merlinsub@t-online.de>]

If you drive dynamicly such a partley ambient boat close to the surface
the hatch will pop up.. Or you have to design an expensive double acting
bajonet hatch. 

If you install a overpressure vale - you will lost the air you later
need to pump the tank out.. 

Small note : According to the class rules for manned submarines you
should able to blow the soft tanks at the surface 4 times and the hard
tanks at the maximum operation deep 3 times...  Hmm.. 4 times .. maybe
the pilot should wear a Astronauts-suit ?

I think the Hunley concept was just that way because compressed air was
not avialable during these days.. 

Spurdog use a simillar Concept. After the owner decides not to refill
the pressure-air-storage-tanks anymore because of to much corrosion
inside the tanks he take surfacing the following way : He starts the
diesel on the seafloor at about 30-40 feet or so and the diesel breath
from the inside air. The exhaust was vented to the soft ballast water
tanks. After eight times of rotation of the barometic indictor reverse
way the boat normaly surface. Talk inside the sub was not longer
possible inside the boat until somebody open very slow the ballvale on
the hatch to bring the air pressure back to normal pressure..   

regards Carsten and at 2 bars (20m or 60ft) a diver has a "zero" bottom
without decompression of about 40 minutes.  At 3 bars (30m or 90ft)
of 15 minutes. At 4 bars of 5 minutes.

Paul Kreemer schrieb:
> 
> Thanks Bill for the great explanations.  I like those ideas - both
> work creatively with underwater physics and physiology.  How about
> 'regenerative ballasting' for a term?   You'd expect a hybrid ambient
> sub would need some sort of regenerative system, like any other hybrid
> vehicle.  :-)
> 
> It sounds good to me to limit cabin pressure to two atm total.  I
> don't have my old PADI dive tables with me but it looks like the Navy
> tables give 310 minutes no deco time at 35 feet.
> http://home.flash.net/~table/table/p0000149.htm
> That seems like a very useful dive time, considering that you're in a
> relatively warm and dry compartment.  And very different from the 15
> minutes of bottom time that these same tables give for 120 ft.  Of
> course a person would probably use a dive computer or other tables and
> get some different numbers.
> 
> Would you guys say that a hybrid ambient would be a little more
> complicated, or just different, to design and operate than either a
> pure 1atm or a plain ambient dry sub?  The ballast tanks are plumbed
> into the crew compartment and so could allow water to enter.  Dan
> notes that the cabin would need to resist an internal overpressure (or
> have a good overpressure valve?).  And I'd think that the hull would
> have to be strong enough to handle the max operating depth with a
> cabin pressure of just 1atm.
> 
> Paul




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