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concrete pressure vessel
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Concrete Floating Structures

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The captain nemo float out - seasteading / Sub movement finished - Submarine Yacht / Is submarine living space expensive? / concrete pressure vessel / Concrete submarine project / submarine yacht / concrete submarine yacht supporter club / Submerged living space bubble concept basics / Exotic Submerged Bubble Hotel / sea orbiter / Current Turbine Concrete Hull /

 

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I would go for a dry exhaust (no adding of seawater to the gases) . There are many forms to bring concrete in place and hold it in place until it cures.

You best start with a clear idea how much liquid concrete you need to hold in place every day. For example if you plan a 50 ton boat and want to build it in 6 months - you just need to form and hold 27 kg of concrete in place every day. So your form needs not to exceed the size of a bucket.

Check the forming of Troll A below - in relation to the total building volume their form does not exceed the "size of a bucket" either... nobody is even thinking about building a tubular structure like Troll A or a highrise building in "single shot pour" that is probably a concept error... you may want to rethink it...

 

3-alimak-hek.jpg



-- Edited by admin on Saturday 3rd of December 2011 10:39:35 AM



-- Edited by admin on Tuesday 16th of October 2012 12:31:06 AM



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Wil- ok i get how to do it-but what about the changing shape of the hull--do you just build a new form every day to adjust to the shape?   in theory this seems like there are only two possible ways 1. to build a small form which can be somehow adjusted as you progress a foot or so at a time on the horizontal axis- ormthe form is just rebuilt as the need arises each day...if the hull was justa tube--in my case--then its easy to do it in one shot--at only 22 ft..but it culd also be done with a slipform in ring formation...?

 

how do you intende to cool your engine??..a radiator could work well here-- or i was panning to run a piping into my ballast tanks as a type of enclosed cooling system...i wonder where Madsens sub exits the exhaust--ive looked and cannot find out where he does this...



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it just hit me--you could make the slip form on a horizontal axis but the length of the sub- not the width!!??... then you just do a small pour per day..unlike the troll "a" which does its on its width...so you make a form for the inner diameter- then slip form it for the outer dia. in a tube shape-- its even easier though with a ring type form...
wil- i still need to find a cheap solution for submerged night running...what r you planning on using?

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u-boatdreams - keep in mind that the exhaust sistem is where corrosion is taking place fastes - from outside marine corrosion from inside corrosive exhaust gas - so keep the whole sistem in a position where you can access and maintain it easy - inside a ballast tank is probably not the first choice...



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once you realize that your form must just hold a bucket full of concrete every day - you can start thinking in creative ways to make it changable - why not make it of lego blocks for example - why not hammer it out of a copper sheet - why not heat form a thermo plastic, why not make the form like a wicker basket - etc. etc...

get creative! forget a plywood form and one shot pour of a simplyfied cylinder  - get creative with the forming process instead of simplyfy the boat shape.

There is a good reason why all aquatic animals have perfect streamline shapes - you will regret any compromize on shape when you get into the water.

Try all the materials, try all the forming axes, make models, make test forming processes - this will guide you down the right path...

Concrete is a liquid material that can take all shapes in the world - don't give away this advantage - start forming small things to make errors at low cost - when you get crafty with material and forming try something bigger - remember big for your build is bucket size... avoid any costly "throw form away"...



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other than most yachts subs have a 2 circuit cooling sistem to avoid water pressure inside the engine block when diving (engines are not built for cooling water under high pressure).



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Wil- if the engine is inside the pressure hull, there wouldnt be any pressure on the engine..if the system is radiator or heat exchanger cooled within the pressure hull?

my model-


http://www.youtube.com/watch?v=-rX1DhR3wOQ

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a open one circuit cooling as implemented in many yachts means that seawater flows directly trough a engine block. At dive the water entering the engine block would be under pressure so you have INSIDE pressure in a direct cooling.

 

Nice model - looks good !

 



-- Edited by admin on Tuesday 6th of December 2011 06:03:32 PM

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hi Wil--thanks for the compliment on the model..

The only thing i think we disagree on is the hull. I have plans for the william bauer u 2540. which is my ideal...

 

where we differ is that i believe a civil sub needs to have some good surface running characteristics. there will be many times owners will want to run on the surface to see the light of day -lounge on the deck, while underway.

the uboat style has all this and is well suited for diving too...

and they wont be needing deep diving as in a military sub. the dives for cruising will only be 30-100ft or a bit more. at least this is what intend.

Yes its still good to run the sub below the surface with a snorkel. but i want to be able to run on the surface from time to time in calmer weather. fact is the engine i have is 30 hp at 3000 rpms and 36 at 3600 plenty of power for light running on the surface in nice weather.

 i  could use keel cooling with heavy steel pipe?....this should solve any intake pressure issues... these pipes ony need to withstand about 2-3 atms. can be run under the sub hull. (they are the type of piping used for steam pressure applications)-then  back to the sub being a closed system -shouldnt experience any pressure variations. or go with a radiator as in a car or truck.

what about night running submerged?..there must be a sensible but inexpensive alternative to the sonar you mentioned...?

as long as you have charts and run so your cameras can see on the surface--wouldnt that be ok?plus at night you want to avoid a deep dive anyway?

that software you mentioned is big bucks!!



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I do not disagree with you - and i understand that you want surface running capacity (everybody who lacks submarine yacht experience wants it - the reason why i build the boats i build now, is to let people experience their different quality and not desire unrealistic design features any longer) - i am just sure that you will not run on the surface when you have your sub in the water. Surface running is just a bad idea and you will find out very quick why when you do it.

It is for good reasons why mother nature never in 400 millions of years developed a surface swimming animal - surface swimming is for a short crossing over of a land animal - it is no option at all for a aquatic animal. Whales swim below the surface although they started as land animals - this is not a rare development, all branches of the animal kingdom as soon as they get aquatic they go below the surface - reptiles, turtles, crocodiles, seals, etc...

It is just a bad idea to displace in the surface layer - for drag, for waves, for hog and sag, you try it - and you will find out why.

The idea to lounge on deck while you cross an ocean is not realistic - the only place where yachts enjoy a deck is in a protected marina or a lagoon - you can enjoy a sub deck in the same circumstances just the same way.

For a realistic picture how submarine yachting compares with surface yachting check here.

You might want to check why not even big surface floating concepts like yachts and cruiseships use the decks very much at sea and orient their living space to the inside.

57313279.jpg

the truth is - in the high seas nobody is enjoying neither the view nor the climate on deck.  At sea you neither enjoy tropical direct UV light that burns your skin, nor spray or nordic rain. Average people enjoy decent protected space at sea. There is no "calm weather at sea" for a small boat of below 100m size (except the doldrums) - being on deck of a small boat in open sea is a fight 24/7- not a dinner place setup.

wil




-- Edited by admin on Thursday 8th of December 2011 02:33:27 PM

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perhaps your right Wil- last night i did some calculations and it seems that my uboat design for it to be suitable to build at 60 ft would only have a 6 ft dia pressure hull--this is not acceptable..so ill stick with my model design. I have been out in 25 ft seas,..and also in flat calms--im sure on a hot sunny day offshore of the coast there will be times i will enjoy the deck of my sub...perhaps not while underway but i want to feel the ocean breeze ..while not rare- a force 5-10 gale wont be something that happens all the time. on the great lakes where ill be operating there are lots of nice days you can lounge on the deck of a boat. whole tourist industries are built on touring the great lakes going from shelter to shelter...
on the open ocean while voyaging ill also have the capability to run in snorkel mode...this way i am not limited. the only differencde in my hull design and yours is mines bit more mackerel shaped, with a boats bow..thats all...it will run at 7/8ths submerged on the surface...but the hull will withstand wracking-hogging sagging- pounding, those are stresses a long unsupported boat would need to worry about- the curved and monolithic design of my sub -as well as it being concrete-will minimalize those stresses. a ferro-hull is extremeley rigid.
but ahs enough flex as to handle these sresses. now --how about night running while submerged in a storm??..there has got to be something low tech that can help with navigation at night?

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I understand your thinking - you might consider that the "bow" of your boat is not really working like the bow of a small boat (cutting the surface layer) - the nose of your boat will work more like the bulb bow of a ship - so you may want to shape it that way - round - what cuts the surface layer and the waves in a sub at surface running is the sail (tower) - the nose is still below the surface - even when running on surface, so a "cutting edge" on the bow is probably not a desireable design feature.

images?q=tbn:ANd9GcTvJ2ixiNOQZq9Nuok7aABXMoG-yqRLNlItXRGabX0ISA4zpexhGA images?q=tbn:ANd9GcQpYbxyrZ2g02t8qMZWVrAkTz6UjpT0pnw90EtI2br-bp3oM9oJ




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Having a snorkel solution with a high mast is also the best way to solve the navigation - you just have a day/nightview camara in your snorkel top combined with a GPS that is economic and efficient.

The idea that a sub needs a "different navigation" than a surface ship is only true for military subs that stay submerged for months under the ice ...

A submarine yacht just navigates the same way as any other yacht.



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peters sub-to me- looks very inefficient running his hull just below the surface...

 2784122793_f446d30b1c_o.jpg


 



-- Edited by u-boatdreams on Saturday 10th of December 2011 08:55:47 PM



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revised version



 



 



 



 



-- Edited by u-boatdreams on Saturday 10th of December 2011 09:34:29 PM

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The hydrodynamics of a surface vessel and a submarine vessel is different.

The number one concern for a surface vessel is the wave build up - any wave is energy - so if your vessel produces waves when moving around the energy that is contained in these waves comes directly from the engine and is lost for propulsion.

The best way to have a vessel produce cero waves when traveling, is submerge it a bit - the differerence in energy efficiency is a factor 5 in propulsion requirement.

This is why the whole idea of surface running was basicly eliminated from submarine concepts after WW1/2 when engineers started to understand better why submarines that are whale shaped are so much faster than everybody expected in first place.

There is no concept that is efficient in both worlds surface AND submerged - you have to choose one - and optimize the concept for it. Trying to make a concept that is good for both is trying to sit between two chairs.





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Wil--I tweaked my design a little and like what i have...the masts are 22 ft tall...

 

 

class: civil
propulsion:  Diesel-electric
l.o.a- 52 ft
beam (pressure hull)- 7 ft outer diameter
beam hull inner  6 ft 8 inches
displacement  submerged aprox (salt water)- 36 tons
displ.(fresh water)- 35 tons submerged
displacement surfaced- 26.27 tons (fresh water)
''     ''      ''        ''       ''    -27.12  (salt water)
range-10 000 nm
speed surfaced-7 knots
''  ''    ''   submerged-3 knots
submerged run time- 2.5 - 4  hours
materials- pressure hull- concrete/steel or ferro-cement- or fer-a-lite.

alternative vessel design:

replica of the type XXI german uboat- manned 1/4 scale



-- Edited by u-boatdreams on Tuesday 13th of December 2011 08:24:30 PM

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looks nice - i would go for a less elongated shape your speed of 7 knots does not really require a long thin hull ... so you can have a living space inside that gives you more comfort...

I would suggest you build a mock up of plastic and wood to check the look and feel of the living space.

 Whale%20humpback%20copy_big.jpg

A humpback whale shape can give you 20 knots and much more standing height .... a tuna shape 1:4 still capeable of high speed underwater.

you might want to compare the walktrough videos of our hull with the walktrough videos of peters and carstens hull to get a clearer picture how living space distributes in a long tube, compared to a blimp shape. The problem in a long thin tube is that the "necessary hallway for the walk trough" eats up all the available space. You understand that inmediatly if you check the "inside the hull" videos.

It is a typical problem that surges when you start "designing" a shape on paper in first place - it is much better to design a living space with plastic sheets over a wire rib skeleton in a 1:1 mock up. It gives you a much better feeling how the living space will be - you will end up with a much broader and shorter shape for practical reasons.

 

 

Euronaut Carsten Standfuss Walktrough - 



UC3 Nautilus Peter Madsden Waktrough

 

Wilfried Ellmer concretsubmarine.com Cartagena Walktrough

 



-- Edited by admin on Sunday 21st of October 2018 01:08:01 PM

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Wil- in the future-who knows, i may want to sell her-then build another- i noticed-people do like replica's.

because of this the nuke sub and the type XXI are the most sought after designs for resale. however --my reasons for the slender design is not space-or speed- but for transportation purposes. I have a budget of 25 000 U.S. Using off the shelf parts for most things and -using easy systems and inexpensive systems i.e. concrete- pressure washer pumps.cheap bilge puimps and actuators on 12v systems, small diesel -used batteries, etc. I can accomplish this . however add another 4000.00 to the craning costs and trucking costs to the launch site, and i am almost looking at 6 years of building then trucking-as it is-its 3 to 5 years of my life here. 4000.00 adds almost another year. and by then itll be 4500.00 not 4000.00

 

- thus it becomes a necessity for me to build a long slender hull as opposed to a fatter shorter hull. there are even many reasons to choose the slender hull over the fatter hull-

1. there is a height limit on roads in N.A. i want to have my vessel completed- to do this i need to have the absolute height limited to 11 ft.(about aprox 3 m.)this is because of bridges, powerlines etc.

2. weight. The sub cannot be moved without a crane and big truck- unless it is under ten tons. so--it makes sense to go with a thin composite shell of ferro-cement. in fact i have a polymer modified cement(16 000 psi compressive strength at 2 inches thick!) that might get donated to my project from a company here who is starting out and wants the exposure my sub will surely get. so you can see--that it makes sense to add concrete and steel ballast later, add huge thick concrete bulkheads,tanks-floors,berths etc for weight and cement re-inforcing rings for weight and strength. this can all be done later  after launch.

There is no doubt that your design is by far, more roomier than mine-a true Nemo lifestyle- and im envious of it- and-i wish i had waterfront to build one then launch one the size of yours. but thats not realisitic for me.

most people who build thier own subs will need to go light hulls-move-then build in wieght with superstructure-bulkheads etc as mentioned above.

This is where you come in to fill that need of buyers for a large hulled sub. i will never compete with you for sales of a submarine.- i cannot build one like yours. But the one i have designed is -not bad- for its size with about 600 cubic feet of living/engine area. a 22 ft x 6.8 ft dia pressure hull. so for me it is the size of a pocket sailboat  cruiser. and people have cruised the world in smaller living areas. it has close to what the UC3 has. and for one person--its good.

Whales are a great model for what your purposes are...

***how do you plan to dive without dive planes= you will need for sure to use dive planes. this is becuase of the difficulty of getting an object to sit at a given depth not moving up or down--its very difficult -at least in the models ive built--perhpas not on a larger scale where you can move small amounts of water out of the sub ..but taking in small amounts is another story... i doubt it will be that simple that you dont need dive planes.

what will you use for pumping out ballast? i know you thought of chemicals for an emergency blow but what about a couple litres of water to adjust buoyancy?..

 

my system will use two pressure sprayer pumps(150.00 at princess auto)attched to two 12 volt batts and two 4 hp engines(179.00 each 24 volts) turning it at 3600 rpms. about 2 gpm's...1800 psi.



-- Edited by u-boatdreams on Thursday 15th of December 2011 09:04:50 PM



-- Edited by u-boatdreams on Thursday 15th of December 2011 09:10:09 PM

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Looks like you have your project thought through. I would probably do it in a similar way in similar project circumstances. There is nothing wrong with dive planes - you may want to check on the BEN FRANKLIN project to figure out how diving without dive planes work.

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 Hi Wil- thanks-i have though it out quite thoroughly..lots to consider..

like i made some changes to the sail here..hope it looks better--the last on was too large and lost hydronamic efficiency...



 



-- Edited by u-boatdreams on Monday 19th of December 2011 11:50:29 AM

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Hi Wil--yes I just noticed the direcitonal thrusters on the ben franklin--of course what i meant was that just trying to dive using ballast water discharge or trimming the tanks would be very difficult indeed- there has to be some way of controlling trim and if you plan on using trolling motors this would be quite simple and effective- trying to get the sub to a level depth using just ballasting water- would be difficult at the least..thrusters r an excellent solution...i do prefer the dive planes though--simple and effective.



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HI again Wil-- some time  ago you mentioned that a sub needs only .2hp-2hp per ton of displacement--here are some figures...

  • 1     35 percent is used to turn the propeller;
  • 2     27 percent to overcome wave resistance;
  • 3     18 percent to overcome skin friction;
  • 4     17 percent to overcome resistance from the wake and propeller wash against the hull; and
  • 5       3 percent to overcome air resistance

 if we eliminate 2.  4. and 5, we get 35%+18% = 53%. but this is only half as efficient. may i ask you to clarify your figures for the hp ratings of a sub??

(hull is 1302 cubic ft)

im using about 36 hp at 3600 rpms so thats about .87 hp/  ton of hull.

 

 this scares me now- since it seems i would need a larger engine?? i will be running hydraulics etc and chargers off my engine so theres a lot of energy gone right there..have i chosen too small a motor?



-- Edited by u-boatdreams on Monday 26th of December 2011 07:37:51 PM

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Abstract

The evolution of concrete pressure vessel design is traced in this report, and a summary of the current applications of prestressed concrete for reactor pressure vessels is presented. Important design considerations and methods for design evaluation are discussed. It is concluded that a basis for design compatible with the ACI and ASME pressure vessel codes is evolving, but the maximum pressure limits for which prestressed concrete can be used are yet to be established.

Research sponsored by the U.S. Atomic Energy Commission under contract with the Union Carbide Corporation.

Accepted by T.A. Jaeger. Adv.: A.D. Ross, T.C. Waters.

source:
http://www.sciencedirect.com/science/article/pii/0369581665900992



-- Edited by admin on Tuesday 17th of January 2012 07:23:04 AM

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...have i choosen too small a motor?

no. - the engine you have will work just fine - you have more HP than you will need.

The figure of 2 Hp per ton of displacement is a raw figure for surface yachts. It is considered "the necessary power to push the boat trough the storm of a lifetime" -

for submerged concepts the locomotion energy required is BY FAR lower -

biological evolution engineered a concept (blue whale) with - (0,2 HP/ton) - and a whale is still a "high energegetic locomotion concept"- whale sharks, sleeper sharks, turtles, do still worldwide oceanic voyages of tousands of miles with much lower energetics than whales...

Forget also anything that was written about engine requirements for military submarines -  many of those are designed for operation with the fleet and speeds in excess of 30 knots - there is no use for that kind of speeds in a submarine yacht.



-- Edited by admin on Tuesday 17th of January 2012 07:24:04 AM

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Bulletin No. 31

Test Depth and High Yield

Prior to our most recent publication, "Steep Angles and Deep and Dives" SRC received several inquiries regarding a definition of HY, (high yield) as well as the relation between test depth and crush depth. It is difficult to discuss these concepts without also discussing hull strength. "Steep Angles and Deep Dives", available from SRC for $13.95, provides a comprehensive explanation of submarine hull strength from the pouring of the molten metal to the welding of hull plates. These explanations are sandwiched between narratives of harrowing dives that took American submarines far below their test depths.

The following excerpt is from the hull strength introductory chapter of "Steep Angles and Deep Dives". It provides some basic information on submarine hull strength including the definition of test depth and high yield:

Test depth is a theoretical number corresponding to the amount of area pressure that can be applied to a hull before it is violated by either distortion, warping, buckling or cracking. The pressure hull acts to prevent an equalization of pressure on both sides of the hull surface. When pressure is equal on both sides of a hull, such as is the case in a submarine's external ballast tanks, there is no need to attend to the problem of potential collapse.

Test depth can be thought of as an engineering estimate of what pressure will be required on one side of a hull to breach the hull, taking into account such factors of hull strength as hull diameter, hull thickness, framing, and intrusions. Naval engineers tend to be conservative in their estimates and the varied factors tend to render an estimate as just that, an estimate. The engineers back into the problem by first estimating the crush depth of a hull, then creating the theoretical test depth by a applying a decimal factor to the crush depth. Different national navies apply varying factors. The United States Navy has used a factor of 1.5, but this has changed many times. Of course, computers are able to make such estimates much more trust-worthy, however, the accounts described "Steep Angles and Deep Dives" are, for the most part, in hulls designed before the advent of the computer.

In the American Navy, hull designers depend on the experience of submarines to verify their estimates. Buships requires a submarine captain to immediately notify both Buships and the Chief of Naval Operations in writing when a boat under his command exceeds test depth. The captain's professional career may be jeopardized by a zealous attention to recording a dive that went wrong. Only in wartime can a captain reasonably explain the need to exceed test depth. For this reason submarines exceeding test depth sometimes fail to make note of the dive in their deck logs.

The simplest application of determining hull strength is the hull thickness. The thicker the hull metal the stronger the hull and the deeper the test depth, assuming all other factors are constant. Prior to the Balao class U.S. submarine, hulls were built of mild steel (MS) which had a maximum tensile strength of 60,000 pounds per square inch and a yield strength of 45,000 psi with 23 percent elongation. The thickness of hull plating until about 1943 was specified in terms of the weight of a square foot of plate rather than the actual thickness, and this was gradually increased from 20 pound plate (approximately one half inch) to twenty seven and a half pounds per square inch in the Salmon (SS-182).

Another change in the Balao class was the change in material used for hulls. High tensile steel was a chromium-vanadium alloy with a maximum tensile strength of 50,000 psi with 20 percent elongation. When the composition was changed to titanium-manganese alloy, because of wartime shortages, the strength dropped to 45,000 psi. The Salmon's hull was about seven eighths of an inch thick giving her a test depth of 250 feet. Conning tower shells were thicker as protection against surface guns.

The thick-skinned boats came along in 1942 with a test depth of 412 feet. These boats had the same seven eighths inch thick hull as Salmon, but the quality of hull steel ie., high tensile strength steel had significantly improved. The crush depth of these boats was estimated to be around 450 feet. Fleet type submarines built during the Second World War were to last through much of the cold war. These boats have careers that have lasted over fifty years with many still being used by foreign navies.

After the war the Navy built several fast attack submarines. These had hulls about an inch and a half thick. They had a test depth of 700 feet. The same hull thickness and quality of steel was used on the early nuclear submarines.

A modern nuclear powered submarine normally has a test depth of over 2000 feet. This huge increase in operational depth came about from increasing the thickness of a hull, from strides in improving the quality of steel, from improvements in the manufacturing process and in hull framing.

Steel is an alloy made up of several metals other than iron. These may include chromium, nickel, manganese, titanium and a host of others. Metallurgy is the science of combining these elements to produce an iron metal that meets a specific need, in this case a hull which is resistant to sea pressure. During the Second World War Krupp of Germany and others used advanced techniques to produce hull plating of unusually high quality. America inherited some of the formulae and steel mills benefited by the German experience.

The key to producing metal hulls suitable to deep diving submarines is the quality of yield strength in combination with compression strength. Accurately controlled element content and relatively high percentages of alloy additives produces strength. The compression strength curve is relatively flat until it reaches a point where the molecules can no longer bind, then the metal fails by cracking and splitting. On the other hand it is possible to produce a metal hull that has the quality of bending rather than rupturing. It yields under pressure where its elasticity, (elongation) gradually succumbs to increasing pressure. The trick for the metallurgist is to strike a compromise and to use the correct ratio of alloy elements to gain a hull plate that resists pressure to the maximum through high compression strength, but yields enough to forestall the rupturing of the metal.

Steel strength is often measured by tensile strength. In this test the metal is pulled on both ends until it parts. Tensile strength is related to compression strength even though the tests are opposite, one pulling and the other pushing. For this reason submarine steel strength is often measured in tensile strength, not withstanding the nature of sea pressure as a compression force.

American submarines such as the Seawolf and Virginia use HY (high yield) 100 metals. These designators attend to the elements used in the submarine hull's alloy where essentially the higher the number the more resilient and resistant the metal is to pressure.

The combination of elements to produce an alloy with great strength is only half the story of producing submarine hulls. The second factor in the manufacturing process is the tempering of the steel and shaping of the plates into a final form. Once again, the basic concept is that a slow-cooling steel tends to be resilient and a quick cooling steel tends to be brittle. Metallurgists in the middle ages learned this early on and after shaping a red hot sword on an anvil plunged it into water. This gave the sword a fine cutting edge resistant to chipping and dulling. The down side was that when struck by another sword it tended to shatter rather than yield. Thus, a submarine's hull plating is cooled at a specific rate designed to produce the best combination of stress and yield factors.

The shaping of the plate in the factory is accomplished with huge hydraulic rollers. The shaping process is also a compromise. Some alloys are cold rolled. This is the optimum in terms of preserving the alloy's strength in the shaping process, however, as the thickness of the plate increases the effect of the rolling becomes less and less. The modern mill now uses computers to cold roll submarine hull plates. Each pass through the rollers bends the steel a small amount until after many ( in some cases hundreds) of such passes through the rollers the plate conforms to the correct hull curvature.

In determining the diameter of the pressure hull the engineer takes into account the metal thickness that will be required to meet a given strength level. The less the diameter the thinner the metal can be. The size of machinery largely determines the diameters of submarines. As the design of the submarine progresses the diameter of the hull inevitably increases. (Modern Trident missile submarines have a forty three foot diameter pressure hull) This necessitates a thicker hull where the alloys used and the shaping process are constant. Once again, the hull design process is one of compromise where interplaying factors are balanced against one another until a final design with an estimate of test depth is reached.

The curved plates of metal to make up the submarine's hull are further strengthened by frames. Lateral framing was known to the Vikings, although they started with a hull shape and only after the strakes had been laid did they imbed the frames into the preformed hull. Submarine hull strength is in large part a function of frame strength and spacing. Cross sections of frames are normally "T" shaped and can be within the pressure hull, on the exterior of the pressure hull, or both. The externally braced hull was the standard in submarine design, because piping and conduit cannot penetrate frames without compromising strength. With modern welding techniques it has been possible to grip the hull plate to the frame with such force that external framing is successful.

The distance between frames is crucial to determining test depth since this distance is where a compressed hull will yield or fail. The distance is a design function taking into account the factors described in this section.

The cylinder is the optimal shape for a submarine hull. A sphere is better still, however, the shape of a sphere does not accommodate a moving vessel through water. Only in experimental and exploration vehicles is the spherical hull shape used. A submarine is in essence, a long cylinder, made up of many sections welded together.

The tapered ends of the fleet type submarine (forward torpedo room and after torpedo room) called for innovation since the cylindrical form had to be compromised. These compartments were flattened for hydrodynamic reasons. Fleet type boats had exterior framing, however, in these end compartments the frames were interior as well as exterior. The deviation from circularity although small, produced a bending moment putting the shell plating under compression and the face plate of the frame under tension. Thus, the mass-produced fleet type boats had framing partly on the inside and partly on the outside of the pressure hull.

Three dimensional curvature for modern hemispherical bows require conical shaping, and tapered hull plating that in turn requires extensive welding.

The welding of the many plates and commensurate framing necessitates the greatest care. The weld seam must have the same strength as the abutting hull plates. This means that if welding is accomplished by hand the welder must be of the highest technical competence. Although a submarine may be similar to others in its class each is essentially hand built. Automation is limited, but computerization is extensive.

Hull butting is exact. Each cylindrical hull section must precisely match the adjoining section. Each cylindrical section has its edges ground to an approximate forty five degree knife edge. When two sections are mated the two edges form a trough. Actually, there are two troughs, one on the inside of the cylinder and the other on the outside. The welder (or machine) places the first bead at the deepest point of the trough. The next weld layer is placed on top of the deeper layer. As the process continues and the wedge shaped trough widens, more and more beads are placed side by side to fill the trough. Many hundreds of beads are required to bring the level of beading to the surface of the abutting hull sections. It is a long and tedious job and quality inspections are constant.

Unfortunately, a perfect cylindrical hull with precise welding and engineered frame spacing must be punctured to allow various pipes, coaxial cables and rotating shafts access to the exterior of the hull. Wherever such a hull opening occurs the hull must be reinforced by building up the thickness of the surrounding area. The larger the opening (such as for hatches) the stronger must be the build-up. Even when every effort is made to compensate for the loss of strength from a hull opening the point of violation will be the point of failure when the hull exceeds test depth.

Time destroys the hull from several directions. The metal itself fatigues over time. Additionally, the sea takes its toll with corrosion eating at the metal. Hull modifications requiring welding, heat the hull and thereby reduce the effectiveness of the initial tempering. Nicks, gouges and scrapes collectively take their toll.

The Fleet Type boat designed and built during the Second World War were subsequently equipped with snorkels and modified into Guppies. These were often given to other nations under various alliances. Many of these boats are still operating as naval units in foreign navies. They are only now being replaced by more recently built boats.

http://www.submarineresearch.com/bull31.html



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submarine depth ratings
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Submarine depth ratings
From Wikipedia, the free encyclopedia

Depth ratings are primary design parameters and measures of a submarine's ability to operate underwater. The depths to which submarines can dive are limited by the strengths of their hulls. As a first order approximation, each 10 meters (33 feet) of depth puts another atmosphere (1 bar, 14.7 psi, 100 kPa) of pressure on the hull, so at 300 meters (1,000 feet), the hull is supporting thirty atmospheres (30 bar, 441 psi, 3,000 kPa) of water pressure. (Note: The one atmosphere of air pressure at sea level is balanced by the roughly one atmosphere maintained inside the sub, so it does not normally strain the hull).

Design depth is the nominal depth listed in the submarine's specifications. From it the designers calculate the thickness of the hull metal, the boat's displacement, and many other related factors. Since the designers incorporate margins of error in their calculations, crush depth of an actual vessel should be slightly deeper than its design depth.

Test depth is the maximum depth at which a submarine is permitted to operate under normal peacetime circumstances, and is tested during sea trials. The test depth is set at two-thirds of the design depth for United States Navy submarines, while the Royal Navy sets test depth slightly deeper than half (4/7ths) of the design depth, and the German Navy sets it at exactly one-half of design depth.[1]

The maximum operating depth[2] (popularly called the never-exceed depth) is the maximum depth at which a submarine is allowed to operate under any (e.g. battle) conditions.

Crush depth, officially called collapse depth[2], is the submerged depth at which a submarine's hull will collapse due to pressure. This is normally calculated; however, it is not always accurate. Submarines from many nations in World War II reported being forced through crush depth, due to flooding or mechanical failure, only to have the water pumped out, or the failure repaired, and succeed in surfacing again. One of the most popular stories of this occurring was the story of U-96, in the movie Das Boot. Note that these reports are not necessarily verifiable, and popular misunderstanding of the difference between test depth and collapse depth can confuse the discussion. (Planesman error sometimes causes submarines to exceed test depth by a few feet or meters during trials; note that a one-degree up-bubble on an Ohio-class boat indicates that the stern is some ten feet or three meters deeper than the bow.)

World War II German U-boats generally had collapse depths in the range of 200 to 280 meters (660 to 920 feet).[citation needed] Modern nuclear attack submarines like the American Seawolf class are estimated to have a test depth of 490 m (1,600 ft),[1] which would imply (see above) a collapse depth of 730 m (2,400 ft).

http://en.wikipedia.org/wiki/Submarine_depth_ratings



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RE: concrete pressure vessel
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this is good stuff Wil...i wish they had a synopsis on alternative materials...Carl t. Fross (see youtube) has written the textbook for sub designers..he has a chapter on alternative pressure hull materials..but the book is 300.00! so its going to be expensive for one chapter..not sure if any library i know of has it...



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last post was by me--not anonymous...



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it will take a century until "alternative materials" will be considered by shipyards building classic military submarines. The reason - a shipyard is in its nature a "block building assembly" line focused on steel plate building and welding as basic techniques. The shipyard staff is trained in steel, the forman is 50 years experienced in steel, the engineers are planning and designing according to steel properties and qualities, the shipyard suppliers are steel suppliers, etc... so for consider a new material you need to build up a new shipyard and close down the old one.

For the navy considering other than steel ships in its fleet it has to build up a new fleet with new maintenance skills new personal, new training proceedures, new handling proceedures, new careers, etc.etc...

So if we will see new materials it is in yacht building and private boats - sectors where you have a "undisturbed free choice" of materials.

It is just the same as glassfiber and composite materials - a shipyard is specialized on either steel or composite - never mixing up both. This is why outstanding concrete floating structures are built more frequently by civil engineers and specialist engineering firms than by "classic shipyards".

If you look at the transition from wood to steel shipbuilding it was not that the established wood working yards switched to a new material - it was that the wood working yards disappeard and new steel building facilities took their place.


The same happens with the experts that write the books - the woodworking expert does not switch to a new material - he disappears with the old material and the old way to do things and is replaced by a new expert who grew up with the new material already writing a new book.

So do not expect steelbuilders to write a "concrete chapter" into their steel books - better search for the advise of civil engineers familiar with concrete and their studies on tubular concrete structures under hydrostatic load.

Wil



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-- Edited by admin on Tuesday 7th of August 2012 03:59:21 PM

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Direct Link Handbook of Acrylics



-- Edited by admin on Tuesday 6th of March 2012 06:42:17 PM

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The first comprehensive illustrated guide to ships lost at sea and the treasures they have yielded, capturing the romance and the risks of treasure hunting. From Roman ships laden with bronze statues to the gold--carrying blockade runners of World War II, this highly illustrated historical atlas is the first comprehensive guide to ships lost at sea and the treasures that have yielded. Tales of shipwrecks. The Atlas features spellbinding accounts of 40 of the most significant shipwrecks of all time. These accounts reveal how and why the ships sank and describe the often extraordinary feats of salvage accomplished through the centuries. There are tales of Chinese junks lost in the shark--infested waters of the South China Sea; of Spanish galleons laden with jewels; of prospectors in pursuit of gold around the world. Salvaged treasure. The Atlas is sumptuously illustrated with photographs of treasure salvaged from the wrecks, including rare coins, precious porcelain, finely crafted jewelry, and even mercury. Illustrations of diving equipment through the ages explain the development of salvage and underwater archaeology. Exquisite thematic maps. Beautiful hand--drawn maps illustrate the seas and oceans of the world during the different historical periods. They highlight the trade routes and ports of an era, detail the cargoes carried, show the notorious black holes that have bedeviled shipping, and plot the positions of some of the most remarkable shipwrecks. Comprehensive gazetteer. Twenty full--color maps plot the sites of over 1,400 wrecks around the world, showing the depths at which they lie. Accompanying profiles give details of the date on which each ship went down, its cargo, and any salvage attempts so far. Many of the wrecks still lie there on the ocean bed, their treasure awaiting recovery. Expertly researched and lavishly illustrated, this outstanding world history of shipwrecks will fire the imagination of everyone who is drawn to the risks and romance of treasure hunting.
  Pickford, whose father worked as a researcher for an English salvage company involved in nearly 100 operations, here chronicles shipwrecks from the Bronze Age to the Vikings, then moves on to Chinese junks, the Levantine trade, the Portuguese and Spanish plate fleets, pirates, gold rush paddle-steamers, and, finally, to the Titanic and other modern ships. To be included, wrecks must have been laden with treasure. Colorful maps detail the historical trade routes and pinpoint the wrecks. A gazetteer surveys over 1400 shipwrecks around the world, including many that have yet to be salvaged; each is briefly described in the "Shipwreck Listings" section. A good history and a welcome reference for treasure seekers. Highly recommended for public libraries.
John Kenny, San Francisco P.L.
Copyright 1994 Reed Business Information, Inc.



-- Edited by admin on Thursday 8th of March 2012 12:35:13 AM



-- Edited by admin on Thursday 8th of March 2012 12:36:29 AM

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Hey Wil--thanks for tlal the info--ill be sure to look up some of those links - saw your new honeycomb flaots--great idea...



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Reading List:

Basic Concrete Engineering for Builders with CDROM / Design of Concrete Structures / Strength Design for Reinforced - Concrete Hydraulic Structures Engineering Manual on CD / Design of Offshore Concrete Structures / Construction of Marine and Offshore Structures, Second Edition (Civil Engineering - Advisors) / The Dock Manual: Designing/Building/Maintaining / Theory and Design of Concrete Shells / Thin Shell Concrete Structures / design procedures of reinforced concrete shell structures (JGJT 22-98) / Understanding Structures / Concrete Planet: The Strange and Fascinating Story of the World's Most Common Man-made Material / Concrete Construction Manual (Construction Manuals (englisch)) / Large Wind Turbines: Design and Economics / Dynamics of Offshore Structures / Offshore Technology in Civil Engineering / Design of Offshore Concrete Structures / Concrete in the Marine Environment (Modern Concrete Technology)

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Concrete Floating Structures

Surface Floating Concepts:

The axes of ocean colonization / floating real estate building lots on the water / Plate Seastead - Plate Floating Element for Ocean Colonization / Catamaran Concrete Floating Elements - Base for Ocean Living / Floating Concrete Breakwater Marina / Ocean colonization how to get there / Ramform ship island as ocean base mobile stable scaleable / small honeycomb floating concrete structures in cartagena / Seabreaks for dampening colossal ocean waves / Ocean colonization technology / Ocean colonization company / Oustanding floating concrete structures / ocean colonization general considerations / Interesting projects for ocean colonization / Aquaculture, business, trade, mininig, energy, salvage, making money afloat /

Submerged Concepts:

The captain nemo float out - seasteading / Sub movement finished - Submarine Yacht / Is submarine living space expensive? / concrete pressure vessel / Concrete submarine project / submarine yacht / concrete submarine yacht supporter club / Submerged living space bubble concept basics / Exotic Submerged Bubble Hotel / sea orbiter / Current Turbine Concrete Hull /



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. . . . . . . . . . . . . . . . . . . . . . .



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I know this post is late, and I do not want to sound overbearing or over critical, but I have to say, that if you are considering using gas, in any form to create lift by displacing a liquid weight under sea pressure, you are going to kill yourself. It is not practical, unless you are only going a few feet under water. And even at that, dangerous to depend on. You must pump out the liquid. You need to do some calculations on how quickly gas compresses. You will be shocked. You would have to store enormous reserves of pressurized gas.

You are also missing a point on buoyancy, which is more important than weight.

And you need to study about thin wall and thick wall stresses.

Concrete acts much more like a thick wall than steel, but it still needs signicant thickness.

Your previous proposal, using a gas tank, and as also replied to, needs significant added stiffeners. I think you have not grasped the purpose of these, and the difference between internal and external pressures in thin walled applications.

You NEED to do some more research. You have too many mistaken ideas.



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im not sure who your reply was directed at-- but

1. in a 1 atm sub there is no compression of gas inside the sub. this is why military uses compressed air.

2. i dont plan on using gas anyway for ballast blows or any other purpose..i plan on doing exactly what you suggested using high pressure pumps to control trim bouyancy etc..read the whole thread..



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please discuss the issues of underwater liftbags and volume control in a thread apart  - this thread is reserved to discuss the theme of a concrete pressure vessel (pressure hull).

http://concretesubmarine.activeboard.com/t51354639/lifting-weight-underwater

Two remarks: Gas liftbags are widley used in the submarine salvage industry - tank blow out in submarines is also fairly common - so i see no reason to put a red flag on the topic of buoyancy control with gas scuba divers do it all the time inspite of its "easy run out of control factor"....altough i agree that a submarine with a noncompressible hull can use water pumps for a much easier much preciser and superior buoyancy control. See the example of BEN FRANKLIN on that topic. The boat was able to hang stable in ANY depth they choose with no active buoyancy control at all - our concrete hulls can do the same trick even better because they are even less compressible.



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------ Wilfried Ellmer / yook3 / latinindustry / imulead / tolimared / mantillaexport / ibaguevende / concretesubmarine / cartagenavende / bogotavende / marcelamancilla / / @nautilusmaker / ------



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Get a foothold in ocean colonization:

concretesubmarine.activeboard.com/t49529137/oceanic-frontier-develpment-investment-foothold-in-ocean-col/

The Captain Nemo Lifestyle:

concretesubmarine.activeboard.com/t43942461/the-captain-nemo-float-out-seasteading/

Why oceanic business is the next big thing to come:

concretesubmarine.activeboard.com/t56680633/the-reasons-why-oceanic-business-is-the-next-big-thing-to-co/

Ocean sphere fish farming:

concretesubmarine.activeboard.com/t55433095/ocean-sphere-the-next-wave-of-sustainable-fish-farming/

Ocean colonization gallery:

imulead.com/tolimared/concretesubmarine/picturegallery/concept/

Big things have small beginnings ocean colonization transition, potential:

concretesubmarine.activeboard.com/t58002383/big-things-have-small-beginnings-transition-capability-key-f/

Sustainability on Planet Earth only the oceans can safe us:

concretesubmarine.activeboard.com/t58921987/sustainability-population-growth-consumption-growth-ocean-co/

Free spirited oceanic lifestyle global mobility:

concretesubmarine.activeboard.com/t58935854/subdue-to-nobody/

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| Wilfried Ellmer | nautilusmaker® |

nautilusmaker.com/t/what-you-should-know-about-me/1584/1

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