TC.
Calculate the volume of the size you want in cubic meters and
you have how many tons it will be approx. The sizes you are throwing casually
around will weigh in at 24 tons. This forum is to help people with knowledge
so they can design their own. It is not to do the design for them. You have
been given advice and access to the tools you require. I think it is now up to
you to do some work. We are not going to argue with you. We will help where
we can and I have had a lot of assistance from the good people on this forum for
which I am grateful, but you need to be clear on what you want to do and the
budget you have. If you are serious then you have a 3 year project minimum.
Cheers, Hugh
From:
owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of T.C. Craig
Sent: 20 September 2009 10:20
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Hello; Design; Materials; Thanks
Jay,
Thank you for the clarification.
"I think the issue that most of the people on here...that it doesn't
really cost any more to go to a deeper depth."
I understand that reasoning, and it's extremely valid. However,
this reasoning represents a cost/benefit analysis rather than an analysis of
design viability. Furthermore, it speaks to the philosophical idea of
"as deep as you can afford" which makes sense, considering the amount
of work is the same. However, it's also a calculus based on sunk costs,
and fails to include continuous running costs and maintenance.
Consider this perspective: a thin shell of mild steel will forgo deeper depths,
but what it loses in ability it gains in maintenance. Mild steel plates
of a thin profile are more ubiquitous than plates of a greater thickness --
more or less. In fact, the thicker the hull plating, the more specialized
it becomes. In a pinch, I could always weld a thick plate to a thinner
one and enjoy roughly the same psi-resistance, but the reverse is not true, as
the vessel can only withstand the pressure of its weakest plating. When
it comes to a boat in near continuous operation, the higher the serviceability,
the lower its running costs. All of which is well worth remaining in "milder"
30' - 60' depths.
Now, in terms of budgets, I think I can agree with that assessment. Most people
aren't' used to building in terms of volume and displacement. Honestly, I
modified the dimensions of a sail boat figuring the greater part of the
weight/interior placement was done. I added 5' fore and aft for
control/engine stations and included another half-foot to the beam; all
cylindrical, of course My design might be a bit ambitious for my
resources, and I appreciate you pointing that out. I have no frame-of-reference
for what is "big" in terms of submersibles, which is one of the
reasons why I'm posting here.
In terms of "safety" on something like the Russian sub, it wouldn't
be too difficult to infer it's dimensions and ability. Although this
isn't mentioned, I figured it's an ambient submarine, considering it's depth
restriction to 30', the number of portholes, and it's comparative
lightness. At one point his sole motive force were bicycle peddles
attached to a propeller. There's no reason why this design couldn't be
into something safer.
I have my reasons for wishing to keep my op-depths shallow, and my only request
is that the community graciously help me clarify this concept.
-T
On Sat, Sep 19, 2009 at 11:27 AM, Jay K. Jeffries <bottomgun@mindspring.com> wrote:
TC,
I think the issue is that most of the people
here on the list that will give you some advice have looked at what it costs to
build a shallow ops boat and one that has a deeper range and conclude that it
doesn’t really cost any more to go to a deeper depth. When they also run
the numbers, they find that a sub with the dimensions you propose is outside of
the budget of most home-builders. And finally, a larger sub presents
launching and handling issues. There are very few large PSUBs, 1
completing construction and 1 undergoing sea trials in Europe along with a very
innovative sub being built in Colombia for a US party that uses unusual hull
materials that if successful, will open up opportunities for more large PSUBs.
When the membership considers subs similar to
the Russian tinniest sub, there are a lot of safety issues that remain
difficult to resolve. Safety is paramount and the submarine community
(the big boys) is very conservative, as a result they have few large
catastrophes, many PSUBbers also hold these values.
Don’t be discouraged, the PSUB group sees a lot
of new comers approach the list with ideas of building a larger submersible
with some characteristics that are out of the norm. Over time, these new
comers if they are serious and stick around, usually end up with a more
economical and easier to build smaller sub. Those that don’t clearly
define what they want their sub to do early on and perform a lot of research
and supporting calculations usually pay for it later upon launching and sea
trials where stability and trim issues finally become obvious…there are a lot
of sub lawn ornaments and garage queens out there.
R/Jay
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: Saturday, September 19, 2009 1:43 PM
Subject: Re: [PSUBS-MAILIST] Hello; Design; Materials; Thanks
Dan,
If by "sarsacm" you mean my last comment to Alan, I can tell you that
I wasn't trying to be sarcastic. I was having an honest moment of
revelation.
That being said, you might be sensing some frustration with the process.
When I say, " I'd like to build a 25' long submarine with a 6.5' diameter
that has a crush depth of 80' " what I'm hoping to hear is,
"oh! Why didn't you say so. Traditionally, depths of 80' to
100' require roughly 3/8" steel +/- usually reinforced with x-type
stiffeners though you need to run a full calculation.... " Or,
"TC, you're running in such shallow water (6' - 30'), 5/16" or
less would work reasonably at those depths, as would (gasp!) GRP/composites,
but those aren't ABS recommended, of course you'll have to do the full range of
analysis, and probably run ambient."
I think a lot of people come to this board expected to get a very
informal/rough estimate of the viability of their vision, only to be
disappointed by the repetitious suggestion of more research. While
research isn't bad, obviously, I think this board is seen as a resource to fill
in the holes that other research didn't provide. I know that I've had a huge
problem finding design discussions of super shallow depths, that I hoped this
board would fill. Few are designing shallow divers, and even fewer are
talking about them.
For instance, does anyone remember the "tinniest sub in
Russia"? I don't recall his name, but his tiny sub could travel
one-hundred kilometers and dive 30'. And he built it during an era of
sever soviet oppression. That seems like a design to work with. While I'd
certainly change the outside design, it looks like a fun, long distance craft
that gives a nice taste of submarine travel.
R,
-T
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