If someone is concerned about fabricating the hull from a custom rolled cylinder, maybe they should just consider an altogether different approach. If you take the design of Cousteau's diving saucer, you could pretty much have an "instant pressure hull" just by welding together two endcaps. Talk about cheap. Of course that gives you an idea how much more there is to the job than just the pressure hull. Alec -----Original Message----- From: owner-personal_submersibles@psubs.org on behalf of Dan H. Sent: Wed 12/28/2005 8:48 AM To: personal_submersibles@psubs.org Cc: Subject: Re: [PSUBS-MAILIST] Choosing sub design (Was: Carsten in Wired Magazine) Doug, Other then poor welds, on what do you base your safety argument? If it is poor welding, then the person starting with a tank is still in trouble since the tank seams isn't the only welding. I don't know details about propane tanks but assume they are built to standards as good or better then most home built tanks would be. That, and the fact that you get two end caps and the round cylinder all welded together and in one purchase are about the only advantages I see. On the minus side; You have to, clean the smell out of it. You have to, check it for roundness. (a vestal built to contain pressure may not be as round as a vestal to keep pressure out needs to be) You have to fit framing in to it through what ever openings you make for your conning tower or access hatch. You have to crawl in and out thousands of times through the same little opening during construction. Believe me, thousands of times! (damn, I thought that screw was a philips and the straight slot it back on the bench) Working on the interior is so much easier with one end cap not welded on until it has to be. You still have to order fabricate and weld materials for viewports, a conning tower and hatch of some kind. And you still have a sub built from a propane tank, and no documentation for the hull material. Ordering end caps, having a hull rolled and doing some welding isn't difficult! There is so much more to building a sub then the tank. If the two end caps and a steel tube are your pit falls, your probably not going to ever finish it and have a working sub anyway. Dan H. ----- Original Message ----- From: sealordone@aol.com To: personal_submersibles@psubs.org Sent: Monday, December 26, 2005 11:41 PM Subject: Re: [PSUBS-MAILIST] Choosing sub design (Was: Carsten in Wired Magazine) Shipmates, With all due respects, I am thinking "no". To me, there is a very strong "safety argument" to be made for rolling your own. I know of no "safety argument" to be made in defense of using a propane tank. For me, I admit my bias, the selection of a propane tank is in every case, and without exception, evidence that the designer lacks the knowledge base to build a safe submarine. To me it is all very back and white on this one issue. Can someone out there provide the "safety argument" for propane? My mind is open, I have simply never, ever heard the argument. Is there one? Please bring it forth. Again, my mind is open. Doug Farrow SeaLordOne -----Original Message----- From: Joseph Perkel <joeperkel@hotmail.com> To: personal_submersibles@psubs.org Sent: Mon, 26 Dec 2005 17:31:31 +0000 Subject: RE: [PSUBS-MAILIST] Choosing sub design (Was: Carsten in Wired Magazine) I think what Stan just said should be added to the PSUBS ethos for new arrivals to this game. Eloquent simplicity, good job! Joe P _____ From: sfreihof@aol.com Reply-To: personal_submersibles@psubs.org To: personal_submersibles@psubs.org Subject: [PSUBS-MAILIST] Choosing sub design (Was: Carsten in Wired Magazine) Date: Mon, 26 Dec 2005 10:14:09 -0500 Welcome Kris; First, decide what design you want to use. You can choose from a 1 atm sub, to an ambient sub wet or dry. It depends on your needs, capabilities, and skills. If you choose the 1 atm design, most on this list would suggest you "roll your own" hull, but propane tank based designs have been done successfully if you are aware of the drawbacks. The consensus is that it isn't worth the savings because it won't save you much and entails too many uncertainties. Ambient subs are easier to build but have some operational limitations and risks. You need to be a qualified and competent scuba diver first to understand the drawbacks of ambient subs. Again, it all depends on your needs, capabilities and skills. Everything is a trade-off. Stan -----Original Message----- From: Kris <kc0opd@gmail.com> To: personal_submersibles@psubs.org Sent: Sun, 25 Dec 2005 15:00:20 -0600 Subject: Re: [PSUBS-MAILIST] Carsten in Wired Magazine Hello! I'm new to the area of personal subs, and I'm looking for some information. I found the PSUBS web site, which gave us a great start into our sub design. My father and I are attempting to build a sub for use in a freshwater lake, with a maximum depth of no more than 50 feet. At the present time, our biggest problem is finding a suitable tank for the hull. We have considered a used LP tank, but there is the concern about residual LP. What has everyone else done, or what can you recommend? Thanks in advance for your help. Kris ************************************************************************ ************************************************************************ ************************************************************************ The personal submersibles mailing list complies with the US Federal CAN-SPAM Act of 2003. Your email address appears in our database because either you, or someone you know, requested you receive messages from our organization. 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