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Re: [PSUBS-MAILIST] Pressure hull construction
Hi Marten,
I suggest you read the first chapter of the ABS book. The inspector needs to be on site to witness all the critical welds, construction and testing. The builder pays all the costs for the inspector, his travel, his lodging and fees.
But before you touch any hardware you need to submit you design, plans (in triplicate), calculations... for their professional approval.
That is why a home built K-350 for $20,000 costs $150,000+ to build commercially. Even after George Kittredge went through the ringer to get his design certified.
Once ABS is done they disclaim that your sub is safe. The only claim it passed certification. Which is good for one year then you have to recertify.
I seriously doubt any PSUBSers have had their hull certified. Those that build K-boats (K-250, K-350 or K-600) can at least say the design of their sub has passed approval, has a long history of safe operation, and is the most widely home built 1 ATM design.
You get the "warm and fuzzy" by following the ABS spec as much as practicle, build from a proven design, and do unmanned testing at Test Depth. Testing is critical.
Regards,
Ray
Marten Liebster wrote:
>
> When I get around to building my sub, I do intend on following the
> applicable standards in the ABS handbook, regardless if it get certified or
> not. How many personal (non commercial) subs actually get theirs certified
> though?
>
> I believe in the handbook it talks about scanning (ultrasound??) the hull
> and welds to determine the quality.
>
> Do they come to you? If so, it must cost a fortune.
> If you have to ship your sub to them? If so it must cost a fortune.
>
> Seems in theory that's no doubt what one should do. But in practice I'm sure
> that it's cost prohibitive for everyone except for a Mark Cuban or Bill
> Gates.
>
> I'd imagine of that none of the 1 atm subs built by members of this group
> have had theirs certified. So that's what lead to my question of how did
> they achieve a "warm and fuzzy" feeling over the construction of their
> pressure hull.
>
> Marten
>
> -----Original Message-----
> From: owner-personal_submersibles@psubs.org
> [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Hugo Marrero
> Sent: Tuesday, May 04, 2004 4:05 PM
> To: 'personal_submersibles@psubs.org'
> Subject: RE: [PSUBS-MAILIST] Pressure hull construction
>
> Marten,
>
> The American Bureau of Shipping (ABS), Lloyds Ships Registry, and many other
> internationally recognized agencies (which are the equivalent of the F.A.A.)
> do have these standards available. If you purchase the book I mentioned to
> you a few days ago and read it, many of these questions will be answered for
> you.
>
> Hugo
>
> -----Original Message-----
> From: Marten Liebster [mailto:mliebster@tbteam.com]
> Sent: Tuesday, May 04, 2004 12:45 PM
> To: personal_submersibles@psubs.org
> Subject: [PSUBS-MAILIST] Pressure hull construction
>
> Those with 1 atm subs, how is/will be your pressure hull be constructed?
>
> Was/will it be assembled by yourself or by a fabrication shop?
>
> Even if I were to design the perfect (unlikely) psub, I don't know if I
> could trust myself or someone else with my life.
>
> Taking a trip in an airplane is different. There are industry and federal
> standards for the construction, usage and maintenance. Also there are
> rigorous inspections. Plus, each plane isn't a one off creation. Also,
> ignorance is bliss. :-)
>
> So even though I would spec out the proper material and proper welding
> techniques, there's still that feeling of uncertainty. Even it was to be
> pressure tested to 2x operating depth, in the back of my mind would the
> possibility of problems developing over time with things I had built for
> myself.
>
> Safety being the primary concern, this might be a deal breaker for me (not
> for others, it's a personal decision) for a 1 atm sub. I misquoted a figure
> in a previous posting - 100ft = ~6000 lbs of pressure per square foot - I
> incorrectly stated PSI. That's about the max operating depth I planned to be
> at. Doesn't seem to allow for too large of a margin for a badly fabricated
> pressure hull.
>
> This has sparked another related question:
> Would properly engineered (pardon my misuse of English) internal framing
> widen the margin for error?
>
> Thanks again to all who have helped me to better understand how a sub is
> properly designed and engineered.
>
> Marten
>
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