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Re: [PSUBS-MAILIST] Design depth



Just for another data point, mine:

Predicted hull failure depth: 3400m
Planned Operational depth: 300m
Planned test depth: 600m

This is of course subject to change, the two biggest factors
being out of round of the hull and funds available for tests.
I could potentially save a lot of money by halving the
operational depth.

Ian.


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

From: JimToddPsub@aol.com

Sent: Dec 9, 2010 7:42 PM

To: personal_submersibles@psubs.org

Subject: Re: [PSUBS-MAILIST] Design depth

Hi, Alan,
 
In my mind I had picked up "design to twice the operating 
depth." I plan to test to 2/3 of the design depth (US Navy standard) 
which is the same thing as 133% of the operating depth.  
Therefore:
 
Operating Depth    300'
Test 
Depth            400'
Design 
Depth        600'
 
Those numbers might change slightly during the design process, 
but the proportional relationships should stay the same.
 
Jim
 

In a message dated 12/9/2010 8:13:19 P.M. Central Standard Time, 
alanjames@xtra.co.nz writes:

  Hi Jim,
  I remembered the discussion but forgot the details.
  I used to hear all the time on Psubs that you test your sub to 
  twice your maximum
  operating depth, unmanned, for an hour. This might not be a bad rule for 
  home builders
  who aren't going through a certification inspection process; & may be 
  using blown domes
  with their inherent stresses & weaknesses. Also there is the aging 
  process that must weaken 
  the hull, that should be accounted for. I'm still looking at making my 
  hull out of
  fiberglass & there's a bigger margin of error required for that 
  material.
  Alan
   
  
    ----- Original Message ----- 
    From: 
    JimToddPsub@aol.com 
    To: personal_submersibles@psubs.org 
    
    Sent: Friday, December 10, 2010 12:31 
    PM
    Subject: Re: [PSUBS-MAILIST] Design 
    depth
    

    Alan,
     
    My design depth is 600 ft.  Operating depth is 300 
    ft.  Therefore required test depth would be 375 ft.  Failure depth 
    must be slightly deeper than 600 ft.
     
    What test depth would you consider to be best based on the 
    above?  I would have thought 400 ft. which isn't much more than 
    the standard.  We had an online discussion of this in early 
    October.  I'll forward my last post which includes the comments of 
    others.
     
    Thanks,
    Jim
     
    
    In a message dated 12/9/2010 2:45:05 P.M. Central Standard Time, 
    alanjames@xtra.co.nz writes:
    Thanks,
that's a lot smaller margin than I thought, or would 
      be happy with myself.
Alan
----- Original Message ----- 
From: 
      "Jon Wallace" <jonw@psubs.org>
To: 
      <personal_submersibles@psubs.org>
Sent: Friday, December 10, 2010 
      2:25 AM
Subject: Re: [PSUBS-MAILIST] Design depth


> 
      
> I believe for certification ABS requires the sub to be tested to 
      25% 
> above its maximum operating depth.  So if your max op 
      depth is 100 feet 
> they would require it to pass testing at 125 
      feet.
> 
> On 12/9/2010 2:44 AM, Alan James wrote:
>> 
      Does ABS or ASME state what your operational depth should be in 
      
>> relation to your crush depth?
>> & if so is this 
      different for the view ports.
>> I've read with fiberglass there 
      is a 4x safety factor where human life 
>> is 
      concerned.
>> Alan
> 
> 
> 
> 
> 
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