[PSUBS-MAILIST] viewport questions

Wed Oct 29 06:49:45 EDT 2014

Hi Jim,

Actually its used on the inside only. Nothing at all is needed on the
outside.

Thanks,

Alec

On Tue, Oct 28, 2014 at 11:18 PM, via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

>  Hi Alec,
>
> I had forgotten about using dish detergent.  If I recall correctly it was
> used on the inside of the dome for anti-fog also.  Have to put that on my
> checklist before I forget it again.  And it will make the sub smell "lemony
> fresh."  Looking forward to seeing your pics.
>
> Thanks much,
> Jim T.
>
>  In a message dated 10/28/2014 9:09:53 P.M. Central Daylight Time,
> personal_submersibles at psubs.org writes:
>
> Hi Jim,
>
> No mesh and no flushing system, it just takes about two minutes to remove
> the outer dome as its a few screws. This BTW has never been in the water,
> so we'll see and learn when it does. Just off the top of my head, it's
> probably about 8 inches of separation at the apex and tapers to an inch and
> a half at the base.
>
> I don't use Rain-X on the viewports, I use Joy detergent, which is a Dr.
> Phil recommendation that does wonders.
>
>
> Best,
>
> Alec
>
> On Tue, Oct 28, 2014 at 6:00 PM, via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>>  Hi Alec,
>>
>> What is the average distance between the two domes?  Do you have any type
>> of mesh etc. over the 1/4" holes to keep debris out?  Do you have some type
>> of flushing system for cleaning the surfaces between the two?  Since that's
>> an ambient space I'm guessing it wouldn't take too long to remove the outer
>> dome when you want to do a thorough cleaning.
>>
>> All:  Have you been using Rain-X on your view ports and domes?  A while
>> back I saw some ads for another hydrophobic product that claims to be
>> superior to Rain-X, but I don't recall the brand.
>>
>> Best regards,
>> Jim T.
>>
>>  In a message dated 10/28/2014 4:30:30 P.M. Central Daylight Time,
>> personal_submersibles at psubs.org writes:
>>
>> Hi Vance,
>>
>> Actually it starts at 2" thickness, and at the time was the thickest dome
>> Greg had made. It was an iffy proposition, meaning he didn't know if it
>> would turn into sub jewelry or just a deformed glob of expensive material.
>> Luckily it came out virtually perfect.
>>
>> My hull is 31" OD, a little smaller than yours. The window is a 120
>> degree segment, just under 27" OD. So the trick is how to span the gap
>> between the 27 inches and the 31 inches. In the original design, this bow
>> window also acted as a hatch, a la Deep Flight. I made a massive Al ring
>> 31" OD, which telescoped on linear bearings and four 1.25" bars, driven by
>> rams. With ensuing redesign, the need for all that disappeared because I
>> now have a coning tower, so I've dropped the bars and rams, and the seat is
>> now mounted to the hull very simply with four big bolts. It will make a
>> very handy big door into the sub for maintenance purposes, but is overkill
>> and the window could be mounted by using part of your existing endcap and a
>> permanently welded conventional seat.
>>
>> One big decision is the window seat geometry. I like conical because PVHO
>> rates it for twice the life of square edge, but it requires fabrication
>> capabilities that Greg didn't have for the window and I didn't have for the
>> seat. So its a square edge for the simple reason that we could make it that
>> way.
>>
>> I should mention the Al ring actually has two domes on it, one inside the
>> other. The 27" dome is structural, and the outside dome is 31" and only
>> half an inch thick. The outside one is just for fairing, to protect the
>> structural dome from abrasion, and to mitigate collision damage. The space
>> between the two domes is free flooding, and there are 1/4" holes around the
>> edge of the outer dome to facilitate that. In a collision, the water would
>> squish out through the little holes, so the thing is basically a shock
>> absorber.
>>
>> As for calculations, I will paste the window calcs below. It is really
>> just table lookups from PVHO tables, a simple cook book. The seat would
>> have to be calculated with FEA. I didn't have FEA, so I did like the Greeks
>> and Romans. You know why the Partenon is still standing? Try to do
>> engineering calculations using Roman numbers! It was too complex, so they
>> simply made everything massive. The seat is one integral piece of aluminum
>> of ridiculous proportions, and it backs into a 516 gr 70 ring on the end of
>> the hull that is an inch thick and two inches deep. I'm pretty confident
>> that ring isn't going wobbly before something else does.
>>
>>
>> Best,
>>
>> Alec
>>
>>
>>
>>
>> ----------------- pasted ------------------
>>  Viewport Depth Rating per PVHO-1a-1997
>>
>>
>>
>> The following calculations and specifications are for a sperical sector
>> window with square edge, to include an optional O-ring seal.
>>
>>
>>
>>
>>
>>
>>
>> 1) Determine Conversion Factor (CF)
>>
>>
>>
>> Water temperature  = 75 °F (tropical conditions)
>>
>>
>>
>> From Table 2-2.4, CF = 7
>>
>>
>>
>>
>>
>>
>>
>> 2) Given actual fabricated dimensions
>>
>>
>>
>> tmin = 1.73”
>>
>>
>>
>> Di = 26.847”
>>
>>
>>
>> \t/Di = 0.064
>>
>>
>>
>> Entering table 2-2.10 with STCP, t/Di = 0.064
>>
>>
>>
>> Solving for Critical Pressure = 3,460 psi
>>
>>
>>
>> Since Short Term Critical Pressure (STCP) = CF x P = 3,460 psi
>>
>>
>>
>>
>>
>> Solving for P,        P = 3,460 / 7 = 494 psi
>>
>>
>>
>> \ Safe operating depth for window = 1,139 fsw
>>
>>
>>
>> On Tue, Oct 28, 2014 at 3:48 PM, via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>>> Alec,
>>>
>>> I hope this is still you.
>>>
>>> I've been talking to Greg about a major retro-fit on my K-350--a full
>>> hull-diameter dome segment viewport in place of the forward elliptical
>>> head. He mentioned having built yours (the 1000' version) while we were
>>> talking about thickness and whether to try and use something out of Pete's
>>> junk pile.
>>>
>>> While we were chewing the fat about this, he said that to the best of
>>> his recollection, yours started at 1.5" thickness, and that he could build
>>> it for me (maybe a 150 degree arc segment) for what I thought was a very
>>> reasonable amount.
>>>
>>> My problem (okay, one of my problems) is that I don't really know how to
>>> do the calculations for these things. That said, I'm wondering if a partial
>>> copy of yours might not do the trick for my application (it would be tested
>>> much shallower, 500 feet or thereabouts).
>>>
>>> I don't know how you feel about sharing that kind of thing, but I have a
>>> picture in my head of an acrylic bow K-350 with some fairings and a
>>> Minn-Kota driven Deepworker style propulsion system. I think it would make
>>> a great little boat, and so if I can get the viewport and frame designed,
>>> then it's going to be built.
>>>
>>> It's time to play if I'm going to. So, what do you think?
>>>
>>> Best Regards,
>>> Vance Bradley
>>>
>>> _______________________________________________
>>> Personal_Submersibles mailing list
>>> Personal_Submersibles at psubs.org
>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>>>
>>>
>>
>>
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>
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