Re: [PSUBS-MAILIST] When is a new design OK to be used on Persubs in General?

["Sean T. Stevenson" <cast55@telus.net>]

It should be noted that the prescribed standards are living, evolving 
documents, and not absolute constraints.  ABS specifically states in Section 
1.7.5:

"Vessels which contain novel features of design in respect of the hull, 
machinery, or equipment to which the provision of the Rules are not directly 
applicable may be classed, when approved by the Committee, on the basis that 
the Rules insofar as applicable have been complied with and that special 
consideration has been given to the novel features based on the best 
information available at the time."

Additionally, there are several references throughout the Rules indicating 
that well-reasoned deviations from the prescribed rules will be considered on 
a case-by-case basis.

The bottom line is that the rules as implemented are proven to work.  Feel 
free to do something different, but if you do so, be prepared to do (or 
contract) the engineering, testing and due diligence necessary to convince 
(even if you are not actually classing your sub) the ABS Committee that your 
design is just as safe.  This is how the Rules evolve.

-Sean


On September 7, 2009 20:37:03 Jon Wallace wrote:
> Officially, PSUBS recommends building your sub according to ABS and ASME
> standards.  If there is a conflict between two or more authorities on a
> particular design or standard, we recommend you choose the stricter
> standard or the one that provides the highest margin of safety.  PSUBS
> is not an enforcing authority and therefore can only recommend these
> standards, not insist, require, or demand adoption of them in the
> fabrication of your own personal submersible.
> 
> The "old standby's" as you call them, are proven solutions that work.
> The odds are in your favor, that if you interpret and implement them
> correctly you will return to the surface safely.  So from that
> perspective, the old standby's are not stagnant, but safe bets.  I think
> that for components which are critical to survival, primarily the
> pressure hull and life support, stagnant is a good thing and we want to
> be careful not to move quickly for a replacement.
> 
> However it seems like there is plenty of room for improvement in a
> number of other components to ensure we don't become stagnant.  And I
> think you are correct, if people like you didn't forward new ideas some
> of these areas could become stagnant if for no other reason than
> technology moving forward.  For example, propulsion motors, motor
> placement, propellers, lights, CT design (steel, acrylic dome, acrylic
> cylinder), battery placement, VBT + MBT design and placement, scrubber
> design.  I'm sure there are many more.  These are components where you
> can be as unique and innovative as you like without high risk of
> disturbing the integrity of the pressure vessel.
> 
> So I think you've cast innovation vs stagnant as an all-or-nothing
> argument, when it probably has to be applied and interpreted at a
> component level.
> 
> I think if you make it to the convention it will give us all an
> opportunity to talk face to face and get to understand each other better.
> 
> Jon



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