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Re: [PSUBS-MAILIST] Hello; Design; Materials; Thanks
Concerning making a thin hulled sub for shallow depths, it's really dangerous!
If you design it to go to 30', and you accidentally go 50' deeper you die! Imag
ine what could happen if you slipped inside the sub and directed it deeper b
y accident with the motor on and within a mater of seconds you reach the crush
depth! I would like to have a 200' reserve minimum if I had a submarine, say
250' working depth 500' test and going to 450' in an emergency would most likely
turn out okay.
Alex
On 19-Sep-2009 T.C. Craig wrote:
> PS Dan,
>
> I appreciate the surface boat suggestion, and yes, I have considered it.
> Now, what's wrong with having that craft dive 10 - 20' below the surface for
> brief periods? In other words, what about a submersible that mimics many of
> the qualities of a whale?
>
> On Sat, Sep 19, 2009 at 7:11 AM, Dan H. <Jumachine@comcast.net> wrote:
>
>> TC
>>
>> Hey, How about just building a surface boat with a viewport below the
>> water line. You can go fast, save fuel for those long runs and your already
>> submerged, about three feet depending on how much you have on board.
>>
>> I suggest you do some more research into how hull thickness in used along
>> with rib placement to resist pressure deformation, how the total sub volume
>> affects your subs weight and strength, what materials are available to you,
>> what skills you have to work with the materials you decide to use and what
>> your budget has to be to do what your dreaming about. Maybe you can curb
>> the sarcasm a bit too.
>>
>> Dan H. !
>>
>> ----- Original Message ----- From: "T.C." <tc.craig@gmail.com>
>> To: <personal_submersibles@psubs.org>
>> Cc: <personal_submersibles@psubs.org>
>> Sent: Friday, September 18, 2009 11:25 PM
>>
>> Subject: Re: [PSUBS-MAILIST] Hello; Design; Materials; Thanks
>>
>>
>> PS.
>>
>> I hear the reasoning behind going heavy and diving deeper, nut this
>> comes at the cost of longer distances. Why not go for a thinner hull,
>> shallow depths, and pit the weight savings into fuel and long distance
>> running?
>>
>>
>> Sent from my iPhone
>>
>> On Sep 18, 2009, at 6:13 PM, "Alan James" <alanjames@xtra.co.nz> wrote:
>>
>> Hi TC,
>>> I think the reason people don't design for shallower depth is because
>>> if you are going to the bother of making a pressure resistant hull for a
>>> 1atm
>>> its not much more trouble to go a bit thicker with the metal & hence
>>> deeper.
>>> Given the overall cost of building a sub, going a bit thicker in the
>>> metal is a
>>> comparably small amount.
>>> There is an article on fiberglass in the frequently asked questions on
>>> the Psub site.
>>> As said previous, you've got to go a lot thicker with fiberglass than
>>> metal & hence
>>> the subs displacement is more & you end up heavier, also its a lot more
>>> expensive
>>> & you really have to know what you are doing when laying it up.
>>> Fiberglass has strong characteristics in tension but not in compresion, &
>>> is only strong
>>> in the direction of the fibers.
>>> Maybe fiberglass on a small sub but the size you are talking about would
>>> be a huge cost.
>>> Then you have to buy extra lead to sink as you don't have the inherent
>>> heavyness of steel.
>>> Regards Alan
>>>
>>> ----- Original Message ----- From: "T.C." <tc.craig@gmail.com>
>>> To: <personal_submersibles@psubs.org>
>>> Cc: <personal_submersibles@psubs.org>
>>> Sent: Saturday, September 19, 2009 12:31 PM
>>> Subject: Re: [PSUBS-MAILIST] Hello; Design; Materials; Thanks
>>>
>>>
>>> Dear Sirs;
>>>
>>> First, let me thank everyone for the thoughtful and detailed
>>> responses. You've given me a wealth of information. Thank you.
>>>
>>> After digesting these responses, and reading my original post, it has
>>> become obviouse that I failed to clearly communicate my design and its
>>> intentions as well as the quality of my previous research.
>>>
>>> I guess this is what you get when you assume engineers will read
>>> between the lines...:)
>>>
>>> 1. This will be a 1 atmosphere submarine. I will consider an ambient
>>> if the operational design makes more 'sense'.
>>>
>>> 2. 25' in length (pressure hull)
>>> 6.5' in r^2
>>> 2.5-4' draught when surfaced. Though clearly this is volume/
>>> displacment dependent.
>>>
>>> 3. Operational depth 20' - 50' with excursions into 60'. Crush depth
>>> at 90' -100'. Most operations will be I'm a total atmospheric pressure
>>> of 1.5 - 3.
>>>
>>> I
>>> Might also consider a shallower crush depth and operate in 1-2 ATM
>>> waters.
>>>
>>>
>>>
>>> My point in mentioning WWI designs, monitors, and David boats was to
>>> communicate the spirit of the design.
>>>
>>> I'm aware that David boats "smack" of drug running craft. So do single
>>> engine Cessnas and go-fast speed boats, but that doesn't mean I
>>> wouldn't become a pilot, or built a boat at 80mph.
>>>
>>> I will not comprise my design for a losing war on drugs. I will
>>> declare my flag (US), and allow them to board. But what I will not do,
>>> is sacrice the legitimate freedom to design a boat of my choosing.
>>>
>>> Motorcycles are tough to see. So, like a motorcyle, I will attempt to
>>> make myself as "bright" as possible. Though I do hear the all or
>>> nothing surface argument, and it makes good sense.
>>>
>>> My goal is light "cruising" capability and mostly on the surface. My
>>> operations will be resticted to navigatable waterways, bays, and to
>>> near coastal operations.
>>>
>>> Finally, I appreciate the hull calculators and the ambient facts,
>>> these will not go to waste. I am still considering fiberglass for
>>> inland work. Ive thought about designing to 250' and if the economics
>>> make sense, I might do that.
>>>
>>> Basiclly, I wanted to get a better grasp of the full materials at my
>>> disposal given the pressures I'd be facing.
>>>
>>> Steve, I don't know why people aren't designing for shallower depths.
>>> It seems more accesable using cheaper materials and decent integrity
>>> given it's operational range.
>>>
>>> Sent from my iPhone
>>>
>>> On Sep 18, 2009, ts at 12:57 PM, Ray Keefer <psubs2001@yahoo.com>
>>> wrote:
>>>
>>> Hi TC,
>>>>
>>>> What is the intended purpose of your submersible? Where do you plan to
>>>> operate? David boats smack close to current drug subs and I suggest you
>>>> stay away from them.
>>>>
>>>> You said your vision was for a WWI (which means also WWII Fleet Type)
>>>> profile. For the overall size of:
>>>>
>>>> L: 25â??
>>>> B: 6.5â??
>>>> D: 2.5 - 4â??
>>>>
>>>> I would expect a pressure hull of about 20' long. Using the 2.5' diameter
>>>> that would be an internal volume of 98 cubic feet ( L x pi x r^2 ).
>>>> Using
>>>> the weight of sea water at 64.0 lb/ft^3 this pressure hull would deplace
>>>> 6,283 pounds of water. If you use the 4' diameter the weight goes to
>>>> 16,084 pounds or 8 tons of displacement. Are you ready to trailer or
>>>> move
>>>> multiple tons of submersible?
>>>>
>>>> Your operational depths of 30â?? â?? 50â?? is fine. Though the shallower
>>>> the
>>>> depth the easier it is, even temporarily, to loose c on trol and slip
>>>> passed
>>>> that depth.
>>>>
>>>> "Brief dives to 60â??" means nothing. If you think you might dive to 6 0'
>>>> build that sub to withstand 60'. Actually if you plan to go to 60 ' then
>>>> design the sub to go 3 times that and test it to 2 ti mes that . If you
>>>> are
>>>> paranoid then use even greater safety factor s then 3 an d 2.
>>>>
>>>>
>>>> Dry-ambients have a couple of issues.
>>>>
>>>> 1. The interior volume must be pressurized to ambeint pressure.
>>>>
>>>> The larger the internal volume the more air that takes. While a 20'
>>>> long and 2.5' diameter hull is only 98 cubic feet, that is more then the
>>>> volume of one 80 cu ft scuba tank at fill at sea level. Once you go to
>>>> 32
>>>> feet deep the amount of compressed air you will need will double because
>>>> ambient pressure will double. So just to get to 32 feet you are talking
>>>> four scuba tanks. If you go deeper you will need more tanks. If you
>>>> repeatedly descend and ascend then even more air will be used upon each
>>>> decent.
>>>>
>>>> You must keep the air bubble volume small to keep air usage small. The
>>>> best you can do is just enough space for your body.
>>>>
>>>> Semi-wet or Semi-dry ambients typically have just enough air volume
>>>> for the operators head.
>>>>
>>>> 2. Pressure compenstation
>>>>
>>>> As you ascend or decend the air space must be compensated as the same
>>>> rate as the depth pressure the sub is currently at. Else a pressure
>>>> differential on the hull may split the hull open. Not a good event.
>>>>
>>>> Rapid changes in depth require bigger values.
>>>>
>>>> 3. Escape
>>>>
>>>> A sealed ambient can be dangerous if it starts sinking uncontrollably.
>>>> You must design a way to get out before it decends lower then 150'. I'll
>>>> not degress in to physiological issues of compressed air breathing at
>>>> depth. I HIGHLY RECOMMEND YOU TAKE SCUBA DIVING CLASSES.
>>>>
>>>> The best material for an ambient is fiber glass. Metal hulls are
>>>> typically used on One Atmoshpere (1 ATM) subs. Wood hulls are typically
>>>> NOT used for any submersibles since finding the quality woods of the
>>>> past
>>>> is most unlikely. Plus the skills for such boat building wood working no
>>>> longer exist.
>>>>
>>>> "The vessel will conduct itself primarily in semi-submerged/ low- profile
>>>> condition"
>>>> Why? That is a collision hazard. Plus the drug sub motive of operation
>>>> is going to attract attention. When you are on the surface, be on the
>>>> surface. When you are diving, you are submerged. There is no advantage
>>>> to
>>>> operating with decks awashed.
>>>>
>>>> "The nature of these requirements clearly points to a dry-ambient
>>>> submersible but I wish avoid the dry-ambient for the reasons of
>>>> decompression."
>>>> The only way to avoid decompression is to build a 1 ATM pressure vessel.
>>>> In which case why limit yourself to a mere 60' depth. 250' doesn't cost
>>>> that
>>>> much money considering how much effort and time you will put into the
>>>> project.
>>>>
>>>> For a 1 ATM hull be prepared to learn welding and machining. You will
>>>> also spend money on acquiring those tools or farming out the work.
>>>> Expect
>>>> to spend $25,000 to $35,000 on a small sub. Your dimentions are not
>>>> those
>>>> of a small sub so you will be paying more.
>>>>
>>>> You need to have a clearer idea of what you want to have once you are
>>>> finished before you can go further. I suggest acquiring and reading the
>>>> following books:
>>>>
>>>> Title Author
>>>> -------------------------------------
>>>> ----------------------------------------------
>>>> Acrylic Plastic Viewports Stachiw, Jerry D. Design
>>>> Concepts in Submarine Design Burcher&Rydill
>>>> I Found Israel's Atom Bomb Factory Kittredge, George William
>>>> Manned Submersibles Busby, R. Frank
>>>> Submarine Design Gabler, Ulrich
>>>> ABS: Rules for Building and Classing American Bureau of Shipping &
>>>> Affiliated Companies
>>>> Underwater Vehicles, Systems , and
>>>> Hyperbaric Facilities
>>>>
>>>> Of course you can join our discussion group and ask questions. I suggest
>>>> you read at least one of those books first to allow you to ask informed
>>>> questions of the group. The guys are very helpful but they do not like
>>>> designing subs for the uninitiated.
>>>>
>>>> Regards,
>>>> Ray
>>>>
>>>> --- On Fri, 9/18/09, T.C. Craig <tc.craig@gmail.com> wrote:
>>>>
>>>> From: T.C. Craig <tc.craig@gmail.com>
>>>>> Subject: [PSUBS-MAILIST] Hello; Design; Materials; Thanks
>>>>> To: personal_submersibles@psubs.org
>>>>> Date: Friday, September 18, 2009, 12:20 AM
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Dear Sirs;
>>>>>
>>>>>
>>>>>
>>>>> First, let me say hello and thank you in advance for
>>>>> your
>>>>> time.
>>>>>
>>>>>
>>>>>
>>>>> Iâ??m considering building a submersible with the
>>>>> following
>>>>> characteristics.
>>>>>
>>>>>
>>>>>
>>>>> L: 25â??
>>>>>
>>>>> B: 6.5â??
>>>>>
>>>>> D: 2.5 - 4â??
>>>>>
>>>>>
>>>>>
>>>>> Operational depth 30â?? â?? 50â??
>>>>>
>>>>> Brief dives to 60â??
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> The vessel will conduct itself primarily in
>>>>> semi-submerged/
>>>>> low-profile condition (aside from the conning tower stacks
>>>>> etc.), showing full
>>>>> freeboard only in harbor, or as dictated by
>>>>> necessity. At the desire of the operator, the
>>>>> vessel can
>>>>> make brief, excursion dives up to the aforementioned
>>>>> depths.
>>>>>
>>>>>
>>>>>
>>>>> The exact depths are yet undecided.
>>>>>
>>>>>
>>>>>
>>>>> In other words, Iâ??m looking to build a
>>>>> David-boat/Monitor
>>>>> type vessel capable of excursions to a designed depth,
>>>>> mostly 1.5 to 3
>>>>> atmospheres with extended submerged endurance.
>>>>> Early-early WWI submersibles were treated (and
>>>>> designed) as
>>>>> surface-craft with limited submersible capability.
>>>>> I would like to mimic this design
>>>>> concept.
>>>>>
>>>>>
>>>>>
>>>>> The nature of these requirements clearly points to a
>>>>> dry-ambient
>>>>> submersible but I wish avoid the dry-ambient for the
>>>>> reasons of decompression. Even at thirty
>>>>> feet, there are no-decomp limits,
>>>>> and I would like to avoid these issues if possible.
>>>>> Although Iâ??ve considered limiting dive depths
>>>>> to 20â??, in which case ambient would make sense.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Materials:
>>>>>
>>>>>
>>>>>
>>>>> Some pre/post-Victorian vessels were made of thick
>>>>> wooden
>>>>> planks, metal sheathing, riveted construction, and included
>>>>> deadlights and scuttle-glass
>>>>> portholes. Many of these vessels were
>>>>> capable
>>>>> of greater depths than I am now proposing.
>>>>> What are some todayâ??s hull materials that could
>>>>> give me the same
>>>>> performance more cheaply?
>>>>>
>>>>>
>>>>>
>>>>> Why not consider steel/fiber/carbon/etc. reinforced
>>>>> plastics,
>>>>> or wood, given the limited design parameters. Indeed 60
>>>>> psig is large, but it
>>>>> seems a trifle to many of todayâ??s resources.
>>>>> Far older and more poorly designed submersibles
>>>>> dropped past 70â?? with
>>>>> materials of lesser quality â?? and lived to tell the
>>>>> tale.
>>>>>
>>>>>
>>>>>
>>>>> Would it be folly to sink 5â?? in a hull made of 3â??
>>>>> wood? What
>>>>> about10 feet? or 25? At what depth does wood betray you to
>>>>> the abyss?
>>>>>
>>>>>
>>>>>
>>>>> What about 5/16â?? steel? Would I be
>>>>> called an engineering marvel for using 5/16â??
>>>>> in a vessel designed to dive 5â?? feet?
>>>>>
>>>>>
>>>>>
>>>>> Personally, I suspect that most industrial strength
>>>>> materials will bring you safely back from a depth of
>>>>> <33â?? â?? even those of mediocre
>>>>> design. Informally, it appears that most
>>>>> shallow
>>>>> water (1.5 â?? 2 atm) accidents related to
>>>>> through-hull/porthole failure, as well
>>>>> as entanglement and swamped with decks awash.
>>>>> Hull
>>>>> failure due to pressure buckling appears to be a rare event
>>>>> in shallow waters.
>>>>> I could be wrong, of course.
>>>>>
>>>>>
>>>>>
>>>>> Ultimately, I suppose Iâ??m looking for
>>>>> design/hull-materials
>>>>> advice given the operational characteristics Iâ??ve already
>>>>> mentioned.
>>>>>
>>>>>
>>>>>
>>>>> Thank you all for you time and I look forward to a
>>>>> response.
>>>>>
>>>>>
>>>>>
>>>>> TC
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
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>>
>>
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--
Mailed with XFmail on 19-Sep-2009.
God saved Noah, but Noah had to build an ark!
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