[PSUBS-MAILIST] Deep sea question

[Sean T. Stevenson]

Vance - that doesn't seem accurate. Compressibility of a material is the inverse of its bulk modulus. For ASTM A516 grade 70 carbon steel, the bulk modulus is 140 GPa, and for ASTM B265 grade 5 titanium it is 110 GPa. So the steel actually performs better in that regard. Was the Alvin sphere made from some atypical alloy? 

Sean 


----- Original Message -----

From: "Vance Bradley" <VBra676539 at AOL.com> 
To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org> 
Sent: Monday, April 14, 2014 4:03:39 PM 
Subject: Re: [PSUBS-MAILIST] Deep sea question 

Alvin carried steel drop weights which were dropped at depth. The new system is like the Mirs and the Pisces before them-- vbts and high pressure pumps. Titanium hulls don't compress at depth so are actually more buoyant at 20,000 feet than at the surface due to increased water density. All that has to be taken into account. 
Vance 

Sent from my iPhone 

On Apr 14, 2014, at 5:57 PM, < swaters at waters-ks.com > wrote: 




I have a question I have never understood about really deep sea submarines. How do they go up and down? 
Submarines that use compressed air at 3,000 psi like ours could only go so deep before the water pressure is to great for the HP air. What do submarines like Alvin do? This is probably a really stupid question, but I have never understood it. 
Thanks, 
Scott Waters 



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