[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PSUBS-MAILIST] Git Kraken



Hi guys. I'm in New Mexico and still on the road. May be having some trouble with the rental truck, don't know yet.  I'll finish my dinner and get back on the road. Maybe be in Ft. Pierce by Thursday. Wish me luck. Frank D.



-----Original Message-----
From: Benny Fritz <ctssbowtie@yahoo.com>
To: personal_submersibles@psubs.org
Sent: Mon, Jul 12, 2010 4:32 pm
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"