RE: [PSUBS-MAILIST] 200ton 18meter Live aboard submarine

["Jon Wallace" <jon@psubs.org>]

Hi Ian,

This sounds like a very interesting project, and I wish you the best with
it.  I've read the discussion you and Wilfried have had (posted on his
website) regarding the design of the vessel which was also very interesting.
Given that this type of vessel can be fabricated in multiple sizes, do you
know what size vessel Wil's prototype was, and what maximum depth he
achieved with it?

Wil suggests as part of your discussion with him, that using silicone
sealant alone to hold the viewports in the vessel is sufficient.  However,
according to Stachiw a viewport retaining ring is an integral part of the
thru-hull design and the critical pressure for a viewport of a particular
size would be severely reduced without one.  From what I can gather of your
discussions, the issue you and Wil appear to be discussing is the issue of
retaining the viewports in case of overpressure.  However, the primary
purpose of the viewport retaining ring is not to deal with overpressure, but
to control flexing of the viewport as high pressure is applied to it during
a dive.  Have I misread this part of the discussion?  Have you resolved this
issue, and if so, what did you ultimately decide?  Also, I found it
interesting that the reason Wil provided for not including a retaining ring
was because the metal ring and bolts could corrode (had you considered
Stainless Steel?), but on the other hand he recommends a metal hatch.  Can
you comment on that?

Wil has been pretty straight forward in your discussions with him that he
has no structural calculations, reference data, or actual testing available
to determine the crush depth of the sub that he hands off to you.
Ultimately, it looks like you both agreed that he would test the sub to 30
meters before handing it off to you, even though you've made it clear that
you would like to reach 100-250 meters.  Have you considered taking some of
the $90k for fitting out and extras, and putting it towards a deeper test
trial before taking delivery?  Also, assuming the sub passes the 30 meter
test dive, will that be considered it's operational depth or will you employ
some safety factor and reduce the operational depth for "everyday" dives?
I'm assuming (perhaps erroneously) that your primary purpose for the vessel
is as a yacht, and that diving is a secondary purpose.  Even 10 meters for a
200 ton "personal" sub would be an impressive depth, I would think.

I believe Wil is incorrect when he states, "...PVHO-1 recommended
proceedures are the standard production procedures in acrylic
manufacturing..." and in fact the reverse is true.  Only acrylic
manufactured to PVHO-1 standards would be shrunk and annealed.  You'll need
to discuss this with your supplier to be sure of what you are getting.

Regarding your viewports, if you follow PVHO-1 standards for flat disc
acrylic you'll need a 1.25 bearing ratio for them.  I'm curious if the 50cm
viewport you mentioned is the viewable dimension from the inside of the sub,
or the overall dimension as viewed from the outside of the sub?  You might
also check out the plane disc viewport calculator that is at
http://www.psubs.org/design/calculators.html to see if it matches with
calculations you might have already done regarding dimensions of the
viewports for your sub.

Jon







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