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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...

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...

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).

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

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.

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

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.

 

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

 

 

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

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.

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.

  . 

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

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.

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.

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

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

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...

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

Direct Link Handbook of Acrylics

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

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

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:

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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.

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.

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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