Re: [PSUBS-MAILIST] Ambient vs. 1 ATM: the historical perspective

[Ray Keefer <Ray.Keefer@ebay.sun.com>]

Hi Mike,


> In Campbell's book about the Hunley, he reveals that the ballast tanks
> were open at the top.   The boat was at the same pressure as the
> outside.
> 

Not ambient. While letting water in might compress the air a bit due to
decreasing volume I doubt it was enough to reach ambientcy.


> 
> I wodner if perhaps the 1-ATM crowd might reconsider the ambient
> idea, for shallow-water diving?   If we're not ging deeper than 20
> feet or so, do we need a steel hull?
> 
> 
> Mike Holt

An ambient sub is fine as long as:

1. It can compensate the ambient pressure fast enough if you hit a pocket
   of less dense water.
   
2. You can bail out if necessary.

3. You can drop balast. Really not a good idea though. You will pop up
   in an uncontrolled ascent resulting in rapid air expansion due to 
   decreasing water pressure. Ever blow up a balloon too much. Could be your
   lungs.
   
Each of us has to wrestle with the design tradeoffs and make the best 
decision for each individual. Then work like mad to make it as safe as
possible.

I for one continuiously waffle between going ambient and 1atm. My best
compromise is doing one of each. :)

Regards,
Ray