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: 25’
>>>> B: 6.5’
>>>> D: 2.5 - 4’
>>>>
>>>> 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 30’ – 50’ 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 60’" 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.
>>>>>
>>>>>
>>>>>
>>>>> I’m considering building a submersible with the
>>>>> following
>>>>> characteristics.
>>>>>
>>>>>
>>>>>
>>>>> L: 25’
>>>>>
>>>>> B: 6.5’
>>>>>
>>>>> D: 2.5 - 4’
>>>>>
>>>>>
>>>>>
>>>>> Operational depth 30’ – 50’
>>>>>
>>>>> Brief dives to 60’
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> 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, I’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 I’ve considered limiting dive depths
>>>>> to 20’, 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 today’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 today’s resources.
>>>>> Far older and more poorly designed submersibles
>>>>> dropped past 70’ with
>>>>> materials of lesser quality – and lived to tell the
>>>>> tale.
>>>>>
>>>>>
>>>>>
>>>>> Would it be folly to sink 5’ in a hull made of 3”
>>>>> wood? What
>>>>> about10 feet? or 25? At what depth does wood betray you to
>>>>> the abyss?
>>>>>
>>>>>
>>>>>
>>>>> What about 5/16” steel? Would I be
>>>>> called an engineering marvel for using 5/16”
>>>>> in a vessel designed to dive 5’ feet?
>>>>>
>>>>>
>>>>>
>>>>> Personally, I suspect that most industrial strength
>>>>> materials will bring you safely back from a depth of
>>>>> <33’ – even those of mediocre
>>>>> design. Informally, it appears that most
>>>>> shallow
>>>>> water (1.5 – 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 I’m looking for
>>>>> design/hull-materials
>>>>> advice given the operational characteristics I’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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