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RE: [PSUBS-MAILIST] Acrylic cylindrical conning tower



Alan, Jon

I think that if I was going to do this from scratch I would probably go with a conventional tower there were a few unknowns doing this but it came out nice, I seem to remember Mike saying this was optical grade acrylic, as for distortion I have not noticed any yet I have been standing looking out at my safety divers at varying distances and have seen none but I was not really looking, the main thing I like is its big, being a large frame man( nice for overweight ) it’s very easy for me to get in and out, as things progress I will shoot some video from the tower and post it so you all can see, one thing I will say Mike C did not cut any corners having the tower made it’s a very nice piece of acrylic I wish I would have been able to build the flanges as he had drawn then up out of titanium it was just too much money  maybe after this wreck I can spend another 250k and make the changes I want, I would like to add that without PSUB and all its members I would not have been able to get to this point, the knowledge here is so vast  that we could do anything, it’s so nice if you have a question go send an email and get answers covering every aspect of your question, thanks everyone

 

Brian V. Ryder

brian@subatlantic.com

 

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From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Alan James
Sent: Sunday, July 11, 2010 3:23 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Acrylic cylindrical conning tower

 

Hi Jon,

point taken re material specs.

I had your same reservations re vision out of a tube.

I guess in Brian's case it's not his primary viewing port & it will be interesting to

here his experience if he has extended viewing through it.

I spent a bit of time at a local aquarium trying to get a handle on viewing through acrylic.

They had a number of large tanks of differing thickness & shapes.One an acrylic tunnel

100 meters long. I was looking through at various angles to see the distortion.

I came out feeling slightly nauseous. I was thinking it was because my vision was

being screwed around a lot by the varying distortions. My fear is that you might get that

looking up & down through a cylinder. If you rotated your head from side to side the distortion

shouldn't vary.

Point taken Jens, I've made that comment before re subject headings, will be more attentive in future.

Regards Alan

 

----- Original Message -----

From: Jon Wallace

Sent: Sunday, July 11, 2010 6:24 PM

Subject: Re: [PSUBS-MAILIST] pressure gauge

 


Standard warning here...check the specifications of the acrylic used.  If they do not meet or exceed ASME standards then the material is not acceptable.  I've observed on more than a couple occasions that fabricators who supply acrylic for terrestrial use often use material that does not meet ASME standards (not necessary for furniture and decorative items, etc) and don't even know what the strength specifications of the material is.

I have considered an acrylic conning tower, however Stachiw says that the cylinder provides the worst optical characteristics of any viewport configuration.  It acts as an asymmetric lens distorting the shape of images perceived by the passenger.  As the radius of the cylinder increases, the distortion is less but that also depends upon the thickness.  Stachiw wasn't too specific and I wish he had provided more info about this issue.  I've hesitated designing around an acrylic conning tower because I don't want to spend the money on such an expensive item only to find out the visibility sucks.  I suspect the visual distortion is more noticeable when looking upward or downward since you are peering at an oblique angle to the material and through more of it.  Viewing perpendicular to curvature should have the same viewing qualities as a dome.  Once Bryan gets situated with his vessel I hope he can describe any visual deficiencies, if they exist.

Jon


On 7/10/2010 11:47 PM, Alan James wrote:

Hi Jon & Brian,

There are some pretty big cast tubes that are done as a standard line

that I've seen advertised by Chinese manufacturers. Might be an inexpensive way of doing

the conning tower in the future

I came across this supplier that advertises 500mm diameter & up to 40mm thick 

However the advert is a bit confusing.

4" is a huge thickness. I could imagine forming it would be fun- days in the oven. They'd have to cut the

angles of the mating surfaces first wouldn't they, then clamp & glue it round a form wich they could remove

some how.

Brian you might be able to control your boat from up in the conning tower. Pay a student to interface a

remote play station controller with your motor controls. There is heaps on the net showing how it's done &

ready made circuit boards to help with this.

Alan