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

[Jon Wallace via Personal_Submersibles]

 Exactly how he did it James.  Had a diver outside just hold a metal cover over the outside flange, then unbolted the view port from the inside.  Water pressure retained the cover on the outside once the view port was released.  It was not a waterproof solution, there was plenty of leakage, however it also was not a flood.  It did require fast reflexes and a quick replacement.  Had a bolt rolled away or some other little distraction occurred it would have been a much different story.  I looked for the video again and couldn't find.  It is a video associated with one of the "meets" he had with the submarine community over there.
I was wrong about Madsen drilling his view ports.  He used an internal retaining ring surrounded by attachment bolts with no circumferential support.  See attached photo. 
Jon

    On Tuesday, September 29, 2020, 06:10:09 AM EDT, James Frankland via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  
 
 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.


   

  
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