Train submarine

Discussion in 'Boat Design' started by mistereddb, Oct 26, 2013.

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  1. mistereddb
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    mistereddb Junior Member

    I suggest that as the hull would have to be twice as thick as a conventional submarine to give it the strength needed it would allow it to go sufficiently deep to avoid surface disturbance or satellite tracking when needed.* http://www.atimes.com/atimes/China/LE13Ad01.html

    Regarding beach erosion I would think the railheads would only be put in suitable spots like boat ramps although most of those seem to be up a river or in a bay so that would be something that would have to be given serious consideration.

    As the hull would be the same circumference nearly the whole length like the new British submarine then a plate bending machine would easily roll it especially if you were making 100 trainsubs.

    Not too sure if building a reserve would be that much cheaper I suppose it depends on how long you anticipate any hostilities to be for, maybe it would be better to spend that money on finding our own oil, developing an alternative fuel or converting our trucks and trains to LNG.
     
  2. Stumble
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    Stumble Senior Member

    Doubling the thickness does almost nothing for the stiffness. This thing has maybe 1% the stiffness it needs, increasing the thickness of the plate just adds weight not stiffness. To increase stiffness you have to increase the diameter of the tube. For a 1000km long tube you would need to be... Just a guess here... 400m. Making this the largest ship ever build, it would be wider than an aircraft carrier is long... But it would have plenty of capacity, so at least that's good.
     
  3. parkland
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    parkland Senior Member

    There are many many problems with the design you propose.
    It doesn't take a naval architect to know that a long narrow tube will be extremely fragile in the slightest of waves.
    Make the hull 10x as thick as a normal sub; the length will cause forces that will snap it apart like a cheap toy.
    You are talking about building a giant sub, with simple simple primative techniques, yet expect it to not be found? Even the billion dollar smaller subs are found sometimes.

    The steel cost is probably barely even a part of the expense of a submarine. Think engines, batteries, coatings, electronics, etc. I suspect steel would be 5% of the total construction bill.
     
  4. mistereddb
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    mistereddb Junior Member

    Stumble
    Perhaps you are comparing apples with oranges here and the standard theories are not the same because the trainsub would be sitting on a prepared bed of gravel while loading/unloading and below most of the ocean turbulence when at sea.

    The railheads would have to be in suitable places such as well protected bays with an excellent approach.

    Tank testing of a model would be the only conclusive way in my opinion and even that would not be as reliable as a prototype.

    The logic behind many smaller cheaper trainsubs is that if a couple were detected and destroyed the others would still operate also making friends by including small communities in world trade.



    parkland
    It appears I stuffed up in my calculation of steel cost so.
    6m diameter = 18.84m circumference
    18.84m x 1,000m = 18,840 square metres
    18,840 square metres of 25mm plate @ 200kg/sq. m = 3,760t
    3,760t at $1,000/t = $3,760,000
    So if as you say the steel would cost only 5% of the total then the total should be around $75,000,000 each

    I do not know how expensive the motor etc. would cost but if it is as high as you say then the whole idea would be uneconomical even if it could be technically done which there seems to be considerable doubt by those who know a bit about these things but it has been an interesting conversation.
     
    Last edited: Nov 11, 2013
  5. rwatson
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    rwatson Senior Member

    I dont think so myself ! There is no "most" about ocean turbulence. Its like saying a plane spends most of its time in the air, but over 90% of accidents happen during takeoff or landing. With boats, its a similar story. You can have 30 days of travel totally ruined by 4 hours of bad port approach - very easily.

    You are going to try to maneuver this long and fragile structure sometimes 15 miles through rips, bars, reefs and the ever present large shore swells, Then, somehow, you are going to find a long stretch of smooth, non rocky sand to rest the hull on as you unload a monster train ?

    I dont think so.


    It beats watching TV, thats for sure :p
     
  6. parkland
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    parkland Senior Member

    It would be like driving a 50 ft long, 1/2" narrow glass test tube through a rock quarry.
     
  7. Stumble
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    Stumble Senior Member

    Stiffness isn't something you can do without... Think about it this way, a normal piece of spagetti is about 2mm in diameter and 20cm long. Your sub is going to have a length to beam ration of 200:1 (1000m by 5m). So as a model you need a piece of spagetti 400mm long, or twice as long as a standard piece.

    Take a look at the flexability of that piece and tell me if you want to go to sea in a ship with that much flex.
     
  8. AnthonyW
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    AnthonyW Senior Member

    If I may - and I haven't read each post as I skipped to the end thinking this might all be a hoax:

    It is great that someone your age is trying to improve the lives of others instead of just retiring.

    On this current project though you face combined obstacles of economics and physics. Irrespective of the design constraints and expense, even if it were to work, it would simply not be feasible to run such a machine underwater in terms of the fuel spent vs cargo moved, when compared to moving a simpler more efficient barge close to shore and then using other methods of unloading.

    To illustrate take two tins of soup and put them on a plank that floats. Pull through the water with a weighing hook for fishing. Now take all this soup, decant, and put them into a very long thin pipe. Add some metal BB's to account for the weight of the steel submarine and loss of tin weight. No drag this under the water. Measure with the hook. You should find the pipe offers much greater resistance because its surface area is greater for the volume it is moving. No imagine that effort was fuel.

    This simple exercise should illustrate that very long thin submarines are not fuel efficient. So much so that the cost saving of using a ship vs a submarine could pay for tremendous infrastructure in unloading - a lot of which would be a sunk (one off cost) vs an ongoing cost of fuel. It would be similar to using a car or helicopter to visit a neighbour. Nice idea and appealing for some, but practically the slim advantages of direct flight are outweighed by the enormous extra fuel costs of getting something airborne - let along the servicing differences between the two types of vehicle. Very similar idea to your proposal.

    This simple fact alone would sadly sink you project, let alone the myriad of extraordinary complications added by a vessel of that sheer length and trying to keep it stable through underwater currents. I don't want to get into it, but it is my understanding of the properties of physics and forces applied to objects is that they increase disproportionately with size. I think you are under the impression that a small model underwater train/submarine can be scaled up. It sadly can't in most areas, from material strengths, the impact of forces, or even aspects of chemistry. (Though this is a good thing - otherwise we could have giant insects flying about...) To illustrate this look at a radio controlled car's drive shaft - it is plastic. Scale that up to a large car and imagine the car's drive shaft in plastic and I am sure you can imagine that it is no longer up to the task.

    If you are interested in couriering items by pipe, and I don't mean this sarcastically, there is some very interesting reading on how they move solid items down pipelines via propulsion. In fact as early as the 19th century one German town had a vacuum pipe system for all its messaging (it had a large industrial concern nearby which used the same system.). Makes for interesting reading - it was a very sophisticated and very fast system for its time. I have a second cousin in the oil industry - you would be amazed at what they can move, and what speeds, through pipes. This would however not be the forum for such a discussion.

    All the best with your retirement.
     
  9. kerosene
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    kerosene Senior Member

    if one insists on being right "just because" I doubt they have much to offer in terms of real solutions. Its not that hard to calculate bending moment on 6m diam 1000m structure. Then compare it to 18m diam structure and be amazed how the force to fold the thing has fallen to a fraction. The thickness is just an example of one of the million issues why this idea is pure idiocy. How about the smooth 1000m long flat sand bank that just stays there waiting for next docking?

    Its fine to brainstorm aloud but when you get a bad idea move on to the next one. Getting stuck with bad idea makes it idiotic.

    I suspect trolling.
     
  10. NavalSArtichoke
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    NavalSArtichoke Senior Member

    That's what made this thread so entertaining. The 'train', as it were, left Reality Station long ago. The Train Sub apparently started out as a means to supply unnamed places having no developed port but a significant rail spur and then morphed into a means to provide Australia (which has several well-developed ports AFAIK) with oil and other supplies in case the Chinese, or other unknown parties, turned Bolshie and tried to cut off the Upside Down Continent from the rest of the World. You can't make this stuff up.
     
  11. parkland
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    parkland Senior Member

    The problem here is that submarine delivered fuel would probably be 100$ per gallon, so it's not like people would be filling up personal vehicles, it would only be good for military use.
     
  12. rwatson
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    rwatson Senior Member

    Amazing how many of us jumped on the 'discussion train' of the 'impossible dream' :)

    At least it involves actual research and thinking to refute. As a form of entertainment, its a growing trend.
     
  13. CT 249
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    CT 249 Senior Member

    I'm interested in the idea that a tanker sub would be difficult to find with 2013 technology. When the Germans tried to use submarine tankers, the Allies found and destroyed them all so easily with 1940s technology that the Germans gave up their plans to build more.

    Each Milch Cow (Type XIV) could carry only 25% of its displacement in fuel, which shows the limitation of the submarine tanker idea in reality. And the noise created by a segmented vessel driven by crude (compared to real sub) engines, pushing a skinny tube with containers inside would be a passive sonar operator's dream.

    EDIT; I was wrong to say that the Allies used 1940s technology to sink the tanker subs; some of it was actually 1930s technology.
     
  14. whitepointer23

    whitepointer23 Previous Member

    what about some sort of ship train on the surface, it could be kilometers long and assembled out at sea after loading each segment in port. the segments could be flat bottom like a panamax. the main ship carries the propulsion sytems. maybe an escort tender or tug which would take the required segment into the beach for off loading while the train waits offshore. the segments would have doors like a landing craft. the tender could be made to hook onto the train to for travel.
     

  15. MikeJohns
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    MikeJohns Senior Member

    Because the coefficients of a ships hull are optimised for the best relationship between capacity powering requirements and speed. There's no advantage joining lots of segments together just major disadvantages and they are numerous.

    If you want to move trains you use a roll on roll off ship but you'd only ever do this for short haul breaks in major national rail routes like NZ or Japans.

    If you want to get freight from a train in Australia to a train in SE Asia or vice versa you simply and easily bring the train alongside the ship, that's why containers are so efficient and have taken over just about all freight haulage.
     
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