TC,
We can’t seem to read your mind and provide the answers you are looking for. Normally after a newbie has played with the calculator and found a combination of hull plate and stiffeners that he thinks meets his needs, he then approaches the list and enquires for opinions on his choices. From your comments concerning historic submersibles, it appears that you already have a design chosen and we just haven’t been able to guess what it is. Not knowing your financial or educational background, I have politely tried to tell you previously that a sub of the dimensions that you propose is going to be quite expensive and troublesome to handle.
If you look at the technologies that the drug runners use in their semi-submersibles, there isn’t a whole lot of high tech that goes into their building. What you propose if done in wood and fiber glass would be a short stretch of their building capabilities back in the swamps of Colombia. A steel sub would take a lot more investment in materials and technical capabilities on their part with technical capabilities probably being the limiting factor.
Since we don’t know what your stiffener spacing is, we can’t tell you whether ¼” or 3/8” steel would meet your needs (it needs to be slightly thicker than the ideal thickness to account for corrosion over the life of sub since it will most likely have to remain in the water due to its size). Shape has a lot to do with hull thickness also, to make the calculation correctly plate theory has to be used. Or if no stiffeners, the calculator will tell you the thickness of straight rolled metal. You do not give us sufficient information to give you advice…as someone else has told you, we are not here to design your boat but will give you advice. And be prepared “If they criticize your design, it means they actually cared enough to think about what you propose”, an interesting quote that I recently came across and paraphrased here. If you want to build a replica, do you want to use materials similar to the original hull? If a replica, which one? Davids were not meant to dive, the Holland had a riveted hull, can’t remember much of the particulars on Goubet but I seem to remember that it wasn’t very functional (a quick check on the Web shows that it could not maintain depth or course so was deemed a failure even though supposedly the first electric submarine).
And yes some of us do look at the designs of historical submersibles. I have stood inside of Holland’s Fenian Ram and have laid my hands on his drawings while at Electric Boat along with reviewing the original drawings of my great-great uncle Simon Lake for his Argonaut I & II, Explorer, and mods to his Defender submersibles. Most of these subs are impractical as PSUBs let alone dangerous. The Holland porpoised all of the time and the Argonauts were meant to either operate on the surface or on the bottom (100’ on a snorkel for great lengths of time). Please attend the upcoming conference in Vancouver where I will be presenting a design review of the WW II German 2-man Seehund submersible.
Resepectfully,
Jay K. Jeffries
Andros Is., Bahamas
Save the whales, collect the whole set.
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of T.C. Craig
Sent: Sunday, September 20, 2009 3:27 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Hello; Design; Materials; Thanks
Vance,
I haven't been on this board a week, and with a few warm exceptions, I've been condescended to, patronized, and now accused by a complete and total stranger of running drugs.
1. If I was high enough in any drug organization where I would have to worry about moving tons of product, I can assure you, I wouldn't need the wit nor consultation of internet-engineers.
It's safe to say that South American Drug Cartels are not lurking the Psubs.org board in the hopes of gleaning clandestine information.
2. As many people have pointed out to me, it costs a relative pittance to increase the diving capabilities of any metallic one-atmosphere submersible. Therefore, why would any criminal institution forgo the deeper "insurance" so as to lumber around shallow and more legally dangerous waters when they have the resources to go to 400' ? Indeed, why not go cheaper with an ambient design?
Frank,
Thank you for the exquisite explanation, and detailed information.
You're assuming a lot about what I know about internal and external pressure. For instance, I know that pressure is less like vice grips and ball-peen hammers, and more like a gigantic blanket pressing uniformly across a hull. Though, the analysis makes sense in the face of threats of collision. There was never a mention of a lack of stiffeners. Furthermore, I got 5/16" from a book on submersible torpedo boats from the early 1900's, but now that I think about it, they were probably talking about the fairings. Thicknesses of 3/8" and 1.5" are the most common.
Does everyone really think that I suddenly just decided to build a submersible boat?
How is it that none of you have seemed to catch the fact that these dimension are almost identical to the original Holland? Indeed, that would be quite the project @ 16.5 ton displacement.Even my original 15' X 3.3' diameter is about the same as The Goubet, with a dry weight of 3,196lbs. Though, these weights are based on iron.
Has no one explored the history of early 1900 submersibles? Many of these early designs are almost exact replicas of the david/monitor boat I'm proposing now, with depth limitations of around 60' - though crush depths were around 100'. I know the concept will work as I'm standing on the shoulders of proven designs. What I need to know is how to update the design for modern materials and methods, and what to consider as feasible in terms of personal construction.
If this doesn't seem like a feasible design given the resources of the average builder, why don't you just say so rather than having me reinvent the wheel and call it "learning." Why not say at the outright, "assuming you're not a rich man with lots of space, submersibles beyond x # of feet and Ylbs of displacement are generally unfeasible and cost prohibitive. Might I suggest you keep your displacement between x and x2, and y/y2 operational abilities?" Do you really believe that's, "doing the work for me?"
What if we all had to learn to tie our shoes by first weaving the fabric on loom? "Sorry kid, I had to do it too," strikes me as inefficient, elitist, and certainly unlike any college courses I've ever taken - both CNC machining or any of the Socratic arts.
Hull calculators are used when the real designing begins, but I'm still trying to get basic dimensional references here and am looking for you guys to narrow the broadnesses of information.
-T
On Sun, Sep 20, 2009 at 6:09 AM, <vbra676539@aol.com> wrote:
I don't want to nay-say anyone, but I'm not thrilled with the idea of visits from HS or the DEA, either. Those folks have a vanishingly low sense of humor about some things--and justifiably so.
Vance
Sent: Sun, Sep 20, 2009 9:00 am
Subject: Re: [PSUBS-MAILIST] Hello; Design; Materials; Thanks
Thank you. I was wondering when some one was going to say this.
----- Original Message -----
Sent: 9/20/2009 8:34:47 AM
Subject: Re: [PSUBS-MAILIST] Hello; Design; Materials; Thanks
What type of vehicle would benefit from a low-profile, ultra-light, high-volume pressure hull? A throw-away cargo vessel, perhaps? Hmmm. Its design to dive rarely and barely is evocative. We have had some issues along the western coasts of Central and North America with vessels of this type that were NOT designed to dive, and got caught as a result. None of them were out there for pleasure.
TC. The basic idea here is.......Displacement determines overall weight. If you have a bubble big enough to sit in, it takes X amount of weight to make it sink. You can either use a thin walled pressure hull and strap on a bunch of lead, worrying that you may accidentally reach crush depth and die, or you can spend the same amount of money on a thicker hull, use less lead, and be assured the crush depth is deep enough that you'd never approach it.
The work involved is the same. The overall weight is the same. The plumbing systems are the same. the electrical systems are the same. Thinner ( cheaper) windows still puts the crush depth too close.
There's really not much sense in building for a shallow depth when the added cost is such a small percentage of the total.
It's more logical to build it strong, even if you never go past 60 feet.
A 5/16" hull without stiffeners won't go anywhere near 60 feet without crushing. More like 18 feet and it buckles. Run some numbers through the calculators you've been given.
Remember that a pressure tank is designed to withstand internal pressure like propane. To break the tank is to reach "burst" strength of the steel.
A pressure hull for a sub must withstand external pressure. The steel doesn't "rip" or burst. It merely has to bend in such a way as to make the tank collapse.
Imagine how easy it is to bend a piece of steel just 5/16 inch thick. A pair of Vise grips will bend it. A small ballpeen hammer will bend it. Smack it with a 2X4 and bend it.
Steel is actually cheaper by the pound than lead bricks. It's cheaper to use thicker steel than to buy a bunch of lead to make the same size bubble sink.
-----------You've been given good advice, and pointed in the right direction. Get some books, learn a few basics, and I can assure you your new questions will be quite different than the ones you've posted so far.-----------
It's fun to dream and we encourage people to think outside the box, but we're pretty big on safety around here. What we say, recommend, or suggest reflects on us as a group, and the personal submarine sport as a whole. I may sound a little overly conservative, but the last thing anyone needs is BAD advice when we're talking about a potentially deadly activity like building your own submarine.
Good luck in your quest. It's a long term project and you may have taken your first steps. It's a long road.