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[Rick Patton via Personal_Submersibles]

Jon

sorry to beat this to death but still confused. As I understand it, vessels
for human occupency have 3 depth ratings. Operating depth, unmanned test
depth, and crush depth. So that being said, I am under the understanding
that the calculated safe working depth of the 350 is 350', not 525 or 576'
so are you saying that the 350 can go to those deeper depths as it was
tested to those depths and didn't crush but the (safe working depth is
350)?
as an example to compare this to, a certian size cable will part at 1,000
lbs of pull so they rate it at 250 lbs of pull due to the 4 to 1 safty
factor built in but it is possible to pull it to just under 1,000 lbs with
out it parting? Just trying to put this into perspective, sorry.
Rick

On Fri, Jun 19, 2020 at 3:38 AM Jon Wallace via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Rick, your reference to 600 feet is the first I've heard of a standard
> test depth for the 350.  Deep water is difficult to find in lakes within
> the continental US with only 15 of them being 600 feet or deeper.
> Kittredge lived on the coast and had direct access to deep water, plus
> being a manufacturer and having a need to promote his products as safe
> vessels would have wanted to test near the limits of the vessel.
>
> Let me see if I can clarify the numbers.
>
> 525 feet is 1.5x the nominal max operating depth of 350 feet.  I believe
> most certifying agencies want 1.4 or 1.5 safety margins...I could be wrong
> about that, but it's what I think they want.
>
> 576 feet is the maximum "theoretical" operating depth of the K350 based
> upon nominal usage factors as defined within ASME/ABS design calculations.
> This represents a 1.64 safety margin.
>
> Both those numbers are close to 600 feet which is likely why Kittredge
> tested to that depth, or close to it.
>
> As a side reference, the K600 was tested to 380 psi or 842 feet of
> seawater, and certified by ABS, which is a 1.42 safety factor.
>
>
> Jon
>
>
> On Friday, June 19, 2020, 12:35:19 AM EDT, Rick Patton via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Thanks Jon, that's what I thought you were referring too  but just wanted
> to clarify it as you had said 525 feet and I could have sworn that the
> captain had said to test it unmanned at 600 feet for one hour so I am
> confused as that's more than the ABS calcs of 1.5? Dan Hycroft built a 350
> and tested his to 550' as that's the deepest hole he could find in the lake
> he tested in. James, you just built one, what did you test your's at?
>
> Rick
>
> On Thu, Jun 18, 2020 at 6:18 PM Jon Wallace via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>
> Theoretical crush depth.
>
>
> On 6/18/2020 7:20 PM, Rick Patton via Personal_Submersibles wrote:
>
> Jon,
> Are you talking about test or crush depth on the 350?
> Rick
>
> On Thu, Jun 18, 2020 at 2:50 AM Jon Wallace via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>
> I ran the numbers again in the calculator and got the same numbers.  If I
> change the usage factor to 1.0 then I get 884 feet.  I suppose when trying
> to ascertain a theoretical crush depth a usage factor of 1.0 would be
> acceptable in the calculator.  It's been my understanding that ABS, Lloyds,
> etc, look for a safety factor of about 1.5 which would put the 350 at 525
> feet.  That may explain the 600 foot test depth you mentioned, but even so,
> my opinion is that's overkill.
>
> Jon
>
>
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