Concrete submarine

Discussion in 'All Things Boats & Boating' started by waterchopper, Sep 24, 2008.

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  1. bntii
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    bntii Senior Member

    This is your advertisement in its entirety,
    Your words in context:

    "Here in a simple and cheapest solution for sea freaks who want to solve the under water mysteries. This 20 tons concrete submarine yacht will offer you an adventurous ride at a streaming speed of 3 knots. The innovative design of the hull provides you with a bright interior and a good view. It is 9m / 2,4m and is 18cm thick that makes it strong enough to provide you isolation from the temperature and weather conditions out side. The boat can dive up to 300m and go on for 2 hours at its maximum speed."

    http://www.travelgadgets.org/entry/cheap-and-maintenance-free-concrete-submarine-yacht/

    The specification for this craft is represented as 300 meters in operational depth which implies that it has been tested far deeper to provide a margin of safety in use.

    This craft has only been tested to 52 meters depth.


    As to the rest of my quotations- they are full statements provided by you as the depth of operation that your submarines are capable of obtaining.
    When you say for instance:
    "You could go to 400-600m operation depth if you change viewports by a camara sistem that would not create hull weakening."
    It is clear that you are stating that your vessel can obtain these depths. You do state that testing is required- but you state that this is what you are providing- a sub that will obtain these depths.
    These claims are unsupported by your existing testing and analysis..

    So lets be perfectly clear.

    You are claiming that the submarines YOU are selling have these capabilities.

    You are not limiting your claim to the "concept" as you state above, or the performance of other submarine structures.

    We are far beyond a "concept", you are selling a vessel and defining how it may be safely used.



    Your work and statements are maintained on your site for others to check if they have interest and feel that this perception is invalid as you say.
    Thank you for maintaining the site- it provides a good explanation of your work and thoughts.

    This all is really somewhat off the track of the really interests me about this project- the engineering analysis which demonstrates how the construction methods used enable these hulls to obtain the performance you state.

    As far as debating this analysis- if provided; qualified engineers might step in to help provide insight.
     
  2. Knut Sand
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    Knut Sand Senior Member

    Ok. I'll agree, to parts of this, without hesitation; I, need education. I try to keep an open mind generally. The day I say I've learned enough, that's the day I'll be looking for a job....ehhr well some other job...

    Lurking around on the internet pages (yours, or linked to from them), I found a reference to some earlier tests on circular spheres, don't recall the diameter, though, but vaguely I remember thinking "the diameter of that hull was (or looked to be) quite a lot more than those spheres" referred to in that test. Some exact questions then:

    1. Whats the max hull diameter? Should be in the sales brochure, due to docking/ harbour, etc...
    2. Whats the thickness of the hull in that same area?
    3. Whats the concrete quality? What QA standards do you rely on to qualify/ document the concrete properties? (Most manufacturers in boats for GRP will give you some laminate information, if asked for it; x layers of 4xx gr/m2 multi/biaxial, vinylester/ polyester/ epoxy and type...).
    4. What amount of internal steel support are there embedded?

    Edit: Post 363 is correct? OD 2400 mm 180 mm thick?
     
    Last edited: Oct 21, 2009
  3. rwatson
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    rwatson Senior Member

    Reading Knuts concise and logical response, it occurs to me that half the problem in this discussion is the inability of Wellmer and many of the other "correspondents" to frame a logical question, answer or point of view in concise and grammatical English.

    People complain about Wellmers disjointed, off topic and partially answered contributions, while others fire off equally incomprehensible and poorly structured responses.

    "What we have here is a failure to communicate !"

    Anyone else in here old enough to remember the origin of this classic saying! :)
     
  4. apex1

    apex1 Guest

    Strother Martin "cool hand Luke"

    and I would agree if Mr Ellmer would claim to be a amateur (what he is), but he claims to be a professional builder (what he is not). As such he has to be able and willing to provide substantial information about the vessel he is promoting.
    By so far he was either not willing or not able (I personally assume the latter), to give a serious answer to any of the serious questions he was asked so many times in a polite way.

    Regards
    Richard
     
  5. Knut Sand
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    Knut Sand Senior Member

    Gotta think here a little in the lunch....

    http://www.engineeringtoolbox.com/concrete-properties-d_1223.html

    That give approx 20-40 MPa for portland concrete...
    Well let's use 20 MPa compression?

    The formula goes something like this:

    e = P*D/ (2fz + P)

    e = 180 mm
    P = ?
    f = 20 MPa
    D = 2400 mm
    z= Oh, the reduction factor.....

    Ehmmmm....... lemmmeseee.....

    180 = 2400*P / (2*20 + P)

    (180(40+P))/P=2400

    (7200 +180P)/P=2400

    7200/P+180 = 2400

    7200/P=2220

    P=3,24


    32,4 Bar i.e. something in the area of approx 320 m dept....

    Not 1200 m

    And:
    No safety factor here, unless better concrete mixture is used,
    No reduction for windows (placed in a line...?).
    No reduction for out of shape roundness.
    No reduction for surface finish.
    No visible reinforcement flanges / rings around the windows...

    Think the concrete mixture used must be way better than my assumption here. (4 times?).


    I'd like to stress the fact that I don't feel too comfortable with all the "no's" just above here..... No factor of safety? Well; We will according to this have a safety factor of 0,2667 (or in that area) at a depth of 1200 m..... If it were the inverse, and a Lotto ticket, I'd go for the lotteri...
     
    Last edited: Oct 22, 2009
  6. Knut Sand
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    Knut Sand Senior Member

    Sorry... think there's a miscalculation on my last post.. I'll check it.... A minute...:confused:


    Oh: the converter I used to recheck didn't handle my commas... ,,,,
    It was "correct" (As correct such an idea can be, though...).
     
    Last edited: Oct 22, 2009
  7. bntii
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    bntii Senior Member

    This is an international forum.
    The participant who are not native English speakers will appear disjointed in form (some others as well..... :p ).

    The ability to separate substance from style is a REQUIRED internet skill.
     
  8. Knut Sand
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    Knut Sand Senior Member

    Believe here is some info:

    Quote:
    deep-ocean test was started on 18 pressure-resistant, hollow concrete spheres, 66 inches in outside diameter by 4.12 inches in wall thickness. The spheres were placed in the ocean near the seafloor at depths from 1,840 to 5,075 feet. Over a 13 year period, annual inspections of the spheres using submersibles have provided data on time-dependent failure and permeability. After 5.3 years of exposure, three spheres were retrieved from the ocean for laboratory testing, and after 10.5 years two more spheres were retrieved and tested​

    Quote end....

    4,12 Inches (105 mm) ...
    66" OD (OD 1675 mm),
    5075' (1550 m)

    That's impressive.

    But the relevant formula for a sphere is;

    e = P*D/ (4fz + P)

    That means they assumed the strength in the concrete sphere to be approx 58 MPa. Not bad.

    But then again, no windows, a sphere, safe to assume pretty strictstandards for shape and production too...

    What kind of concrete is actually used? Finished properties?
    And to what quality stardards are the process documented (production test pieces?).
     
  9. dccd
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    dccd Design director

    Lets stay on target

    It is mainly the many ad-hoc questions that drift away from the forums title of questions that are heaped-on the inventor, questions the questioner does not know the answer to anyway! What's the point other than to cast aspersions at the inventor that he is incapable of considering these issues. Issues like this one about "forum decorum" ha ha.... Otherwise in general there is still allot of good back and forth here. I once wanted to tear into a person that was so blinded by his salesmanship and brilliance he had convinced an investor to pump big money into a non-starter, air-cushion ferry idea. I stopped myself from wasting any time since the free market and physics would handle its demise. it died on the table so to speak and I wasted none of my time pointing out the obvious.

    But in the course of the above mentioned bad idea's promotion, I think it damaged the US image to create similar big, advanced marine projects. Since Wellmer is not in the US and seems to have a good basic concept (within his own repeated limits) what's the daily personal attacks for? Both ways?
     
  10. Submarine Tom

    Submarine Tom Previous Member

    "HOOPER" -great movie.

    Well, that's it, I'm off this thread, the dialogue (if you can call it that) is

    pathetic, infintile and unproductive, IMO.

    Tom
     
  11. Knut Sand
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    Knut Sand Senior Member

    Well, as this is a discussion forum I'd like to discuss strength in the design here, keep it open that there is quite a lot that I don't have clear to me, yet... also I'm not a concrete guy... Bot concrete can hold a lot compression, but not close to steel, it'll also be "brittle" in a way that's not too welcome, imnsho... though....

    I fell for the temptation to test out a software update, today.... Not worth a thing, though, as I don't have the info required, no matr properties not the raduis's for the various part of the hull, not the steel reinforcement... So, it's close to goodfornotthing.

    I assumed there should be a tower of some kind...
    I assumed window ø400 mm 1000 mm spaced.
    Hull ø2400, length 9000, bow radius 900....
    1st picture show the design as I understand it
    2nd; hull subjected to 30 bar
    3rd; hull subjected to 120 bar, removed the areas of the hull that have stress below 40 MPa,, not much left for safety margins here....
    The lower picture show pretty clearly my concern for windows located in a pattern alongside the hull.... I've cut away the parts of the hull that does not have a stress above 20 MPa.
     

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  12. rwatson
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    rwatson Senior Member

    Its more like

    "If you cant say Nuthin COHERANT, better to say nothing at all!"

    Sure. its an international forum, but its an ENGLISH international forum, and if you arnt off your face with drugs or ego, you need to be able to put some sensible words down on paper to make the discussion profitable.

    I wish I knew enough to help out Knut in a very thorough and rational analysis of the "concrete concept"

    What we need now is for Wellmer to supply some "concrete" figures - the ones he would supply to anyone who wished to buy a concrete sub from him!
     
  13. rwatson
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    rwatson Senior Member

    Sorry Tom, can't give you the prize. Its a pretty pass when you get Movies quoting older movies.

    "1967 film Cool Hand Luke"

    http://en.wikipedia.org/wiki/What_we've_got_here_is_(a)_failure_to_communicate

    A film worth a look at, if you dont like hard boiled eggs
     
  14. wellmer
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    wellmer New Member

    basic structural concepts

    Hello Knut,

    That is good science stuff - i have some points about the numbers presented.

    Troll A is a tubular concrete structure, operating currently at 303m waterdepth. During mating it reached 350m waterdepth.

    In the studies list there are studies that say that destruction depth for concrete hulls (with a wall thickness geometry that rules out buckling as expected failure mode) is LINEAR - what means destruction depth is a direct and linear funktion of wall thickness.

    Happens that Troll has a wallthickness/hulldiameter geometry that is almost exactly half of the design that we suggest.

    This would place a possible operation depth (including the security factors that where in place during Troll mating) for a portless hull that doubles Troll geometry at 700m.

    That would be operation depth - not destruction depth.

    So your destruction depth analysis places a hull like Troll at a depth of 1/3 of the depth that it actually reached - there must be a flaw somewhere.

    I suggest you have a closer look at the following factors:
    The concrete pressure resistance in engineering books is the number that concrete reaches in any case including security factors - to go for a actual destruction depth you must strip the security factors.

    The resistance testing in the concrete lab is done different as the concrete in a tubular submerged structure is acually loaded. There is a study on the list that mentions that factor and speaks of reaching considerable deper depth than you would expect from unidirectional loading in the lab and puts numbers on it.

    The model looks great, just keep in mind that our hulls do not have a uniform wall thickness. The wall thicknes changes according to keep the hulldiameter/wallstrength RATIO uniform. This means the concrete is under the same load in the whole structure.

    [​IMG]

    Calculate all in highest quality concrete.

    The boat shape can roughly be taken as ellipse shape, no conning tower.

    Thanks a lot for this post that is really a great contribution.

    Keep up posting the good stuff !

    The 1200m "concept reach depth" was postulated for a boat with Deep Quest
    design (portless spheres as pressure hull) - in fact i belive now we can go considerably deeper (according to some testing we have recently done at European Submarine Structures AB) and reach ocean bottom.

    (As it should be clear to anyone, who has industry practice, i can not give away details on the companies R&D - so only thing you will hear from me, is info you could get anyhow elsewhere as it is published by third parties or it is obvious anyhow for the informed observer.)

    [​IMG]


    This would be a boat for surface ship independent deep sea investigation or salvage with ROV.

    The submarine yacht, recently finished, that you see on the picture is for shallow dives only. (relativly compared to the deepdiver - shallow in this case would mean it is possible to push the boat to 600m unmanned test depth - althought we do not target more than 30m for the first round. - in R&D (research and development) - like anywhere else - speed kills.


    [​IMG]

    In that type of "submarine yacht" pushing the hulls absolute depth limits is of no benefit at all. It is just good to have safety factors that exceed the current "industry standard" 1,5-3 (depending on source) by far (our safety factor is around 20 - twenty! - i am not structural scientist but i hear from my advisor board that a "broad discussion" of "structural issues and details" with external experts should not be necessary in this circumstances, it should be "way clear" that the project operates structurally on the safe side, without going in great detail depth.

    What of course always needs discussion is the concept.

    The current boat is a implementation of a concept similar to the concept suggested by "dccd" as a submerged small boat to cross oceans safely.

    thread : Submarine Yacht project
    Post 71



    [​IMG]

    I would like to discuss this concept a bit...
     

  15. apex1

    apex1 Guest

    >>>I would like to discuss this concept a bit...<<<

    Nein, nein Ellmer wir sind noch nicht fertig mit Dir!

    Did the audience notice one single data or proof, about the vessel in question, in the post above?
    Apart from te fact, that the black thingy became a "shallow water" boat overnight.

    Others do the job for you? You still do´nt know anything about concrete, thats it.
    And? Are there results we could see?

    Guys, it is nice to claim fairness and politeness. A scientifical approach is very much appreciated too. But ******** have to be beaten with the big hammer, and Ellmer is one!


    Do´nt worry Tom, he did´nt give me the prize either, though my answer was right!
     
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