Re: [PSUBS-MAILIST] Ballon recovery was: Sub Safety

[MerlinSub@t-online.de (Carsten Standfuß)]

Okay - but a shallow water sub (300 feet )has a only small material
thickness in the 
shell of the pressure hull - indicates plenty of reserve weights
in the bouancy/displacement calculation. That can be better used for
bigger
drop weights - if required. Only the stability calculation limit the 
size of the drop weight - it is nessesary that after releasing the
weight
the stability on the surface is still positive...

Drop weights are much quicker than ballons to release, cheaper and from 
a mechanical point - more safe.  

- In General you have your blown ballast tank. 
- Even the blown or pumped trim tank alone will alos surface the boat. 
- The drop weight will surface your boat. 

- An additional system can be added if you want or require - but why ?  

see you Carsten - We have used two parachutes in some planes - but not
at one person :-) 

Nero Wolfe schrieb:
> 
> Well. given the depth you are working from, you are VERY VERY correct.  it would take huge amounts of air at that depth to inflate the bags just a little.. given that you survived.  I was running on the assumption of a reasonable depth, say less than 100m, and the cabin had already been blown free of water.  I'm thinking this would be more of a "our depth control died, get us up now"  more than "our hull failed, we should be dead" system.
> 
> Running on those asusmptions, just one or two scuba tanks would be able to provide enough gas to get the boat to be positively boyuant....  (if my calculations aren't shot :-) )  Without rigid tanks, there's really no way to surface from really deep water when the hull fails.  Now if a fitting fails, and you need to get up SOON, again the system would still be practical ;-)  It won't work at the depths the CSSX is designed to hit.. then again, not a lot is going to save you if the hull fails at that depth...
> 
> This idea developed from me spending a lot of time wondering what I'm going to do when a boat like the liveaboard decides to blow a fitting or something.  and starts taking on water.  or some hose outside the boat bursts and I loose depth control.
> 
> Given that you were able to not have the hull completely flood, and were at a 300foot depth, what volume of air would be required for the CSSX to be boyant again?