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T.C.
Regarding our publishing a set of predetermined
calculations
to assist on determining depth for a wide range of
most common dimentions:
It's not that simplistic.
I gave you a link to a free calculator &
mentioned the psubs ABS calculator on your first post.
Most subs are made up of cylinders, cones &
hemispherical shapes & have view ports of
acrylic in various dimentions & types, each of
those forms have differing resistance to pressure.
Different subs will have a different confirurations
of parts. So it would be irresponsible to say
" If your sub is X long & Y wide of Z thickness
it will crush at a certain depth."
Regarding your comment that you need to adjust your
expectation regarding the level of
knowlege on this site;- for you to assess that
there is a low level of knowlege on the site
you would have to know that the advice you were
getting was bad, & to determine that you
would need to consider yourself smarter than those
giving the advice, wich makes me wonder
why you are still posting questions.
I have been on this site just over a year &
have been surprized at the level of knowlege here.
There are managers of submersible manufacturing
plants, marine engineers, a naval architect,
marine surveyer,people who have served on
submarines etc.
Regards Alan
----- Original Message -----
Sent: Monday, September 21, 2009 10:44
AM
Subject: Re: [PSUBS-MAILIST] Hello;
Design; Materials; Thanks
Jay,
You make some excellent points. I suppose
I've been a bit vague regarding the source of my inspiration and this
contrived obscurity has forced the group to "read my mind." It's become
clear that I need to adjust my expectations regarding the level of knowledge
and organization to be found on this site. I don't mean this to be
insulting, mind you.
It might be a more efficient process to
publish a predetermined set of depth calculations which fall within the range
of the most common dimensions. It would assist new designs from scratch, and
would help to refine those designs that need updating. When the builder
has decided on what appears to be a chosen "template" he or she could adjust
the particulars as necessary, and with the help of a hull calculator.
Even the so-called newbie, after adjusting his/or specifications could
contribute something to the database of knowledge. In all reality, most
small submersibles fall within a narrow range of specifications given desired
depth and operations. What's the harm in using these specifications as a
template for developing designs?
It's not that I want you to
guess my designs were based on proven models, it just seems that given
the expertise on this board, the soundness of such designs should be
obvious. Again, I don't mean to be insulting. I wrongly assumed
that some of the initial process had been standardized for the reasons of
efficiency - a sort of mathematical FAQ.
This might seem lame to
some, but in order to get a visual understanding of the relationship between
psi and depth, I entered a very simple equation y = X (15/33) + 1 into my
graphing calculator. Perhaps some might think it pointless, but it helps
to me quickly see amount of compression resistance a material must meet at any
given depth. A similar graph might be helpful for depth/thickness
ratios (assuming certain other criteria of the steel). I'd like to write
one myself, but my C++ skills are very basic, and my graphing calculator isn't
that good!
I hear your arguments regarding the expense of my
proposed design. Though, a 100' crush depth and 30 - 50' op depth was
the standard until just before WWII. I do get that I have to shorten my
hull, and the diameter. Most likley the stiffners would be 13" spacings
center to center (is that too many rings?) on a revised 8' hull (5' diameter
here?). 3/8ths has been historically used on vessels much longer
than this. Of course, the depth was limited to around 100'.
As to building a replica, no. I don't want to recreate, I want
to update. But the dimensions of these proof-of-concept are
tantalizingly similar to our projects today.
Finally (a sigh of
collective relief), it seems in some ways we are recreating the wheel when
many of the early submarines tell us the thickness of material, distance of
stiffeners, and operational depth.
(perhaps an ambient design is
best?)
-T
On Sun, Sep 20, 2009 at 1:26 PM, Jay K. Jeffries <bottomgun@mindspring.com>
wrote:
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
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.
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