Re: [PSUBS-MAILIST] Acrylic conning tower

["Alan James" <alanjames@xtra.co.nz>]

Hi Ben,

I've been through all that stuff, looking for cheap domes.

I've had one blown locally in NewZealand, but from what I learn't

along the way, it's best to go with someone that knows what they're doing.

Maybe you could talk Greg Cotteral into doing one?

Emile does a 580mm blown dome he says is good for 450ft operation.

http://www.airesearch.nl/index_bestanden/Page617.htm

Another one is Hydroport in Germany, they do a 600mm dome in two

thicknesses. It's the cheapest cast dome that I could find 1/3rd the price

of a British equivalent.

http://www.hydrosight.com/

Below are some extracts from their emails. If you want their drawings I can

send them off site.

Alan

 Dear  Alan,

I contakt you in request of hydrosight corp. We are a submarine and acrylic domes manufacturer. Our domes you can see on the Model: Nemo 100.

we can offer you this size (Diar.inside 600mm )  for a spezial price. For details please see in the pdf.

bare dome: 2100 ?

complete with flange O-ring and  locking ring : 4350 ?.

 

Dear Alan,

 

our standard Dome is designed for a depht of 100 meters. But we are also able to built this Dome for 20 bar design pressure.

If you need a formal certifiction (GermanischerLloyd - GL) the price increase by 600 ? for one Dome.

.

 

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

From: Benny Fritz

To: personal_submersibles@psubs.org

Sent: Tuesday, July 13, 2010 11:32 AM

Subject: Re: [PSUBS-MAILIST] Acrylic conning tower

Alan,

 

Sorry about the digital signature, those emails go out encrypted by the US Navy.  I do, as you can see have a second email address on the mailing lists. 

 Thanks for the info on the acrylic.  My application is probably smaller than Brian's but I can't know for sure.  The problem that I've been worrying about with the dome/tower is obviously $$$. 

I assume that the domes run higher in cost than the cylinders due to the methods of fabrication.  At this point for me all inquiries would be of a fact finding nature, I still havent finished the final design for the sub.

The numbers you did have are quite useful in gauging the costs for a certain size of acrylic.

 

Thanks,

 

Ben

--- On Mon, 7/12/10, Alan James <alanjames@xtra.co.nz> wrote:

From: Alan James <alanjames@xtra.co.nz>
Subject: [PSUBS-MAILIST] Acrylic conning tower
To: personal_submersibles@psubs.org
Date: Monday, July 12, 2010, 5:31 PM

Hi Ben,

Re the strength comparison of the cylinder to the dome; the hemisphere is a

stronger shape than the cylinder but its a little bit like comparing apples with pears.

A cylinder at 500mm OD, 250mm long (or high) & 20mm thick would have a crush

depth of 1500ft & have a volume of 50 liters.

A hemisphere at 500mm OD, 250 mm high & 20mm thick would have a crush depth

of 2,770ft & a volume of 34 liters.

A nominal hemisphere of a similar 50 liter volume to the cylinder could be 570mm OD.

This at 20mm thick has a crush depth of 2,100 ft.

The hemisphere is more economical with space as its more compatible with the shape

of your head.

The cylinder, in a large dimension like Brian has, can act as your conning tower with a

hatch on top of it. This puts you that much higher above the water level to stop wash

coming in, whereas a dome is mounted & hinges open at the base.

Interestingly enough I just received an email to an enquiry on the price of stock acrylic cylinders.

Their 500mm OD, 20mm thick cast acrylic, at 3 meters long was US $1,300 per piece.

You could get 12 x 250mm sections out of this at $108- each plus freight from China.

I will qualify this before I get "shot down" in that you'd need to go wider for a conning tower

& possibly thicker & check the technical specifications of the material. This was an initial quick

search, but could be a way of coming up with an inexpensive tower / viewport. You could

cut your length off their standard 3 meters & sell the rest off as a fish tank.

Alan

P.S have trouble with your emails in that I can't "reply to sender" because it comes up with a

a message " you cannot send digitally encripted messages because you do not have a digital

I.D. for this account"