[PSUBS-MAILIST] Hull Calc: 78" spheres

Fri Jan 9 22:49:13 EST 2015

Sean,
Can you point me to the direction to writing a spec contract for two hemispherical heads withing the requirements needed? I am still learning and got a long ways to go. I truely appriciate the help.
Thanks,
Scott Waters

Sent from my U.S. Cellular® Smartphone

-------- Original message --------
From: "Sean T. Stevenson via Personal_Submersibles" <personal_submersibles at psubs.org> 
Date:01/09/2015  8:46 PM  (GMT-06:00) 
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
Subject: Re: [PSUBS-MAILIST] Hull Calc:  78" spheres 

Yeah, you really need to cross your t's and dot your i's when tendering a bid or ordering a part to specification. Anything not explicitly spelled out is subject to interpretation or disregard.  I always create completely dimensioned and toleranced engineering drawings for this purpose, in addition to material specifications and test performance requirements, and make clear that if the part doesn't pass QC, the supplier is responsible for correcting the problem. I get such an agreement signed. Of course, I have the benefit of having been doing this professionally for years. Strict hobbyists cannot be expected to be as informed.

That said, I would take the required tolerances, roundness, test procedures and so forth right out of the guides, and present this when getting quotes so that I get the true cost for what I need, and discover right away if it is not within a supplier's capabilities.

How did your dome turn out? Were you able to correct it?

Sean

On January 9, 2015 7:29:44 PM MST, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Sean,
EE did my parts and my dome was quite bent when sitting on the bench.  They told me too bad, it is within ASME specs.
Hank

On Fri, 1/9/15, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Subject: Re: [PSUBS-MAILIST] Hull Calc:  78" spheres
 To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
 Received: Friday, January 9, 2015, 9:24 PM

 I never thought to add the functionality to solve
 for diameter. I'll have to look into that.
 I'll run your calc. Stay tuned.
 Sean

 On January 9, 2015 6:16:50
 PM MST, "swaters at waters-ks.com via
 Personal_Submersibles"
 <personal_submersibles at psubs.org> wrote:
 Sean,Can I ask you to do one more calc for
 me? 516 gr 70 sphere, 1" thick, 72"
 diameter. The 78" was not within ABS rules
 at 1000!
 m. I
think the 72" might just make it, yet give
 me more boyancy than the
 60"Thanks,Scott
 Waters

 Sent from my U.S.
 Cellular® Smartphone

 -------- Original message
 --------
 From: "Sean T. Stevenson via
 Personal_Submersibles"  
 Date:01/08/2015  8:28 PM  (GMT-06:00) 
 To: Personal Submersibles General Discussion 

 Subject: Re: [PSUBS-MAILIST] Hull Calc: 
 78" spheres 

     On 2015-01-08
 19:01, via
       Personal_Submersibles wrote:

     That's what I got.
           Only without the format. Sweet. Thanks Sean.
 It's going to
           take a syntactic buoyancy package to get it right,
 but it
           looks like a decent alternative. A 6 1/2 foot
 sphere displaces
           about a thousand pounds more than the pair of 5
 footers.
           Pretty close, and might be marginally less

expensive. What
           would a 39" radius do for depth in the
 thicknesses you have
           already given?
         Vance

     As
         requested:

         ASTM A516 Grade 70, 78" sphere, 0.75"
 wall:

     ASTM A516 Grade 70, 78" sphere, 1" wall:

     HY-100, 78"
         sphere, 0.75" wall:

     HY-100, 78" sphere, 1" wall:

     Sean

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