[PSUBS-MAILIST] information on viewports

Sun Mar 17 17:02:18 EDT 2024

 Stiffined pressure hull as you describe helps but not enough.  You also reach a point on small submersibles that you have to add so much weight with stiffeners and shell thickness that you no longer have enough buoyancy to get neutral.  This drives you to a larger displacement and then the cost goes exponential with size.
To determine what a pressure hull can withstand, if you use a typical submersible stiffened cylindrical shell with either semi-elliptical or hemispherical heads, then you can download the Psub ABS stress calculator to determine the maximum operating depth that ABS would approve.  If it is a non-standard pressure hull like you are looking at then you need a finite element analysis (FEA) of pressure hull.  Typically this is done with a linear solver for the first pass and a non-linear version to look at buckling analysis thereafter.  If it is a non-standard pressure hull, ABS would also require multiple prototypes of the hull to be fabricated and depth tested in a pressure chamber with strain gages installed at key locations where FEA calculates high stresses.  This level of analysis is normally more than most psubbers want to undertake and thus they migrate back to one of the approved hull configurations.
If you want to stay with the stealth concept, you could build a dry ambient boat.  Then these stress-related issues go away as the pressure inside the boat is the same as ambient water pressure.  The problem with dry-ambient boats of course is the safety-related ones known to scuba divers but amplified because of the boat's ability to move within the water volume much faster.
Cliff
    On Sunday, March 17, 2024 at 03:21:17 PM CDT, Jefferson Tortorelli via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

I have already received some great advice and realize some of you are beyond my knowledge base with regards to hull design. Several members have indicated my flat plate hull is not really great for depth. Not to be obtuse, but what if I had interior ribs spaced closely with a circular cut out, basically kind of a square rib with a donut hole in the center. I originally was going to have a cylindrical pressure hull inside but wanted more room. Is it possible to build my design if I added enough ribs? Plus initially, based on my lack of knowledge, the outer hull that surrounded the pressure was also dry and contained the motor, air tanks, ballast tanks, etc. I now realize that wouldn’t work with flat plates alone.

How do you determine the pressure a hull will withstand. in my searching the internet, I see a number of vessels made using propane tanks. Is that viable? Any suggestions?

Jefferson Tortorelli

Tortorelli Creations

4910 Santa Anita Avenue

El Monte, CA 91731

Cell: 909-908-3795

Shop: 909-370-3131

Website: www.Tortorelli.com

Instagram: @tortorellicreations

From: Personal_Submersibles <personal_submersibles-bounces at psubs.org>On Behalf Of Alan James via Personal_Submersibles
Sent: Sunday, March 17, 2024 12:46 PM
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] information on viewports

Jeff,

If you have experience with resin pouring on your furniture you will be in a good place. 

Alan

Yahoo Mail: Search, organise, conquer

On Mon, 18 Mar 2024 at 8:38 am, Jefferson Tortorelli via Personal_Submersibles

<personal_submersibles at psubs.org> wrote:

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