[PSUBS-MAILIST] K-250 side viewport and dome hatch.

Tue Sep 29 06:08:04 EDT 2020

Swapping out a viewport underwater?  Does anyone have a link to that?  I am
assuming he covered the port on the outside as I believe on that boat, the
ports came off from inside?

Would like to see the video if anyone has it?

On Mon, 28 Sep 2020 at 17:27, Jon Wallace via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Attachment holes through viewports are not currently accepted as safe
> practice even though there are some early model submarines that did utilize
> that configuration.  Sean could likely give a better description but in
> laymen terms those holes introduce stress and fatigue that could lead to
> development of cracks within the acrylic material and seriously weaken it.
> I think the Nekton series used such a configuration but those submarines
> were certified and therefore went through intense engineering study and
> testing.  Any comment Vance?
>
> Peter Madsen drilled holes in his view ports to attach them to his
> submarine UC3, but Peter was also a risk-taker generally and I don't
> believe he ever dove UC3 to any serious depth.  There's a video somewhere
> of him swapping out a view port underwater.
>
>
>
> On Monday, September 28, 2020, 10:57:13 AM EDT, Philippe Robert via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Upgrade on adding view port too. But now I will follow Jon advice,  better
> to do what I see on the plan.
>
> Le lun. 28 sept. 2020 10 h 47 a.m., Philippe Robert <phelop at gmail.com> a
> écrit :
>
> Ok.
>
> Le lun. 28 sept. 2020 10 h 38 a.m., Sean T. Stevenson via
> Personal_Submersibles <personal_submersibles at psubs.org> a écrit :
>
> "Upgrade" is a problematic term. When I design seals, I typically do an
> exhaustive evaluation to determine whether standard O-rings will work, and
> if not, then I start looking at other options. For this application,
> O-rings work well, and I am hard pressed to come up with any possible
> justification to use something different.
>
> Sean
>
> -------- Original Message --------
> On Sep. 28, 2020, 08:17, Philippe Robert via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>
> Thanks for the advice, my goal is to build my submarine safeste as
> possible, but if I can upgrade sealing and design it will be great.
>
> Le dim. 27 sept. 2020 10 h 46 p.m., Sean T. Stevenson via
> Personal_Submersibles <personal_submersibles at psubs.org> a écrit :
>
> In fact, there's nothing inherently wrong with rectangular cross section
> seals, provided they are implemented in the same manner as O-ring seals
> with a captive groove, managed extrusion gap, designed gap fill and
> designed maximum squeeze of the seal. Absent those controls, a simple flat
> gasket presents not only a severe risk of extrusion, but can be subject to
> damage and consequent failure if maximum squeeze is not constrained. When
> properly designed, however, rectangular cross section seals can perform
> essentially as an O-ring seal with integral backup rings in terms of
> extrusion resistance.
>
> Standard O-ring seals have the advantage of having a massive body of
> performance data available, and a freely available comprehensive design
> resource in the Parker O-ring Guide (ORD5700). Seals with custom geometries
> will generally require independent design verification in the form of FE
> models and destructive testing.
>
> Sean
>
>
> -------- Original Message --------
> On Sep. 27, 2020, 18:10, hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
> Hi Philipe,
> You have to machine the dome seat flat anyways, so adding an o-ring groove
> is a small extra step.
> Hank
>
> On Sunday, September 27, 2020, 4:36:22 PM MDT, Alan via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Hi Philipe,
> I don't know of any submersibles that don't use o-rings as the hatch
> sealing method.
> I believe there is a danger of a flat rubber seal extruding inward under
> pressure.
> Alan
>
>
> On 28/09/2020, at 10:32 AM, Jon Wallace via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Follow the plans.  The sections you reference are all related to the
> pressure hull and should not be modified.
>
> Jon
>
>
> On Sunday, September 27, 2020, 04:47:54 PM EDT, Philippe Robert via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Hi all,
>
> I currently make the conning tower. I see on the internet some k-250 with
> front and side viewport in addition of the acrylics dome. Some of the
> viewport is close to the gusset and I assume that is not possible to do a
> 100% weld. Is it acceptable ? Is it ok to drill hole in the viewport to put
> retaining bolts ?  Second question, on the blueprint, the sealing option
> for the hatch on the conning tower is o'ring groove. Is it possible to make
> better sealing like flat rubber strip or something like that ?
>
> Best regards,
>
> Philippe
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