Re: [PSUBS-MAILIST] Newbie

["Michael" <subaquamodels@blueyonder.co.uk>]

Not quite....

When you go down to 10m the pressure will double but as you wrote it you 
implied that (for example) 20m is double the pressure at 10m which isn't the 
case. For every 10m you down you go the pressure increases by one 
atmosphere.

Also, the idea with an ambient is that the pressure outside equals the 
pressure inside and therefore you have zero resultant tensile stress caused 
by the pressure as there is no pressure differential. Obviously there is 
stress/strain in the structure of the vessel but it shouldn't be caused as a 
result of the pressure inside versus that outside.

Someone feel free to correct me.....

HTH,

Michael

----- Original Message ----- 
From: "Raoul H" <raoulhunter@hotmail.com>
To: <personal_submersibles@psubs.org>
Sent: Friday, May 11, 2007 6:01 PM
Subject: [PSUBS-MAILIST] Newbie


> Hi Everyone
>
> I am also new to this and certainly not at your level (yet) :)
>
> I am rather advanced in my first attempt at an ambient sub (later perhaps 
> ....).  But I have one question I would like to pose.
>
> In my design I am maintianing the VOLUME of air (the bubble bit) as I 
> descend and by inflating and then flushing on the ascend.  I have 
> calculated the amount of ballast required for the 'bubble' (calculated at 
> 1ATM) but it now dawns on me that this ballast would double every 10m of 
> depth?!?  Is this the case?  If so the tensile strength of the sub would 
> have to roughly treble (plus safety) for a 20m dive!!
>
> Can anyone advise if this is the case.
>
>
> many thanks
> Raoul
>
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