Submarine Yacht project

[MikeJohns]

Originally Posted by harlemriverman

.....what do you mean by cuttouts?

Ports and hatches presumably with sturdy steel frames (Wilhiem)?
What does all this do when we squeeze it lots

cheers

[harlemriverman]

ah, cutouts...what i am referring to as special load conditions. these concentrate loads in ways that do not compliment the strengths of concrete, typically calling for reinforcement to communicate the loads, typically more of a confinement issue with, for example, the ends of a support wall. thin members become impractical to fabricate where, again for example, converging steel reinforcement to a radial point as in a circular hatch creates geometry problems for the aggregate.

[MikeJohns]

The russian concrete submarine hulls use finely ground ceramic mixed with cement. No aggragate just a dense high strength mortar. They dont have steel in the mortar but do have a thick kevlar lining bonded to the inside.

I think as soon as you start using embedded steel and coarse aggragates you rapidly increase the micro-cracking with each makor load cycle, this starts at aggragate boundaries and more importantly at the steel interface. Then there's the stress concentrations at those darned cutouts which will be the real bugbear.

I had a quick look at the IES site It's not an ideal tool for this.

Even then we are not analyzing Wlifrieds design since he simply doesn't give any detail. The russian design is fairly indicative of what is required for high pressure reliability.

[harlemriverman]

roger that mike, good intel and thanks. kevlar is a big head-start. in your research with russian design, was their any reference or discussion of alkali silica reaction.

ps. are your referencing the use of a depeleted uranium dioxide?

[MikeJohns]

No I was wondering about ASR, no reference to pozzolanic additives and I know nothing of ceramic-cement motars. The Russian mix is basically a high compressive strength; cheap and as close to an isoptropic material as they could manage. No Uranium dioxide either.

[harlemriverman]

mike, you're dead-on with ies. crashed a model of the bow last night twice, sitting in a public hearing with a land use board while occasionally glancing up in agreement. i have to do it in panels but at this point i’ve answered my own questions with this exercise.

wellmer, here's where i'm at with your proportions of 10cm shell thickness to 20m diameter unreinforced concrete submarine.

1. under submerged 30m service loads that you propose, the 10cm unreinforced shell does not work. deflection and cracking. solution is steel, and 30cm is the thinnest I could estimate with steel and membrane. an alternative is to pressurize the cabin but this imposes onerous operating restrictions that i imagine are contra to your objectives for a recreational application...the vessel would be more of a self-propelled commercial diving bell of sorts if pressurized.

2. under surface / dock conditions, steady sea state and gentle winds, the unreinforced vessel also does not work irrespective of practical shell thicknesses. requires skeletal structure and reinforcing steel both. keel / ribs and the need for these getting exacerbated with dynamic loads of a sea condition. special load conditions associated with cleats and cutouts are also problematic for unreinforced cases. could fabricate specialty docking saddles / cradles but that’s restrictive on where the vessel can dock. Cutouts work if there are steel bushings and frames attached to steel, and more analysis is needed as to where and how these assemblies are constructed. you need to be careful with load distributions and differential deflection, so not to cause cracking, leaks, etc.

3. under dry dock conditions, the unreinforced shell requires continuous bracing along bottom membrane with virtually zero deflection, which is impractical. with steel the upper sections need stringers with cribbing and blocking systems that are far more involved compared with a steel vessel, otherwise you will have extensive cracking in areas like the tower. one approach to cribbing might be to keep the formwork used during construction as the cribbing. the most challenging elements to support in dry dock will be the aft fins and screws, and forward or tower fins, as required.

4. under sea state conditions, regrettably i didn't get there with the model. the areas that i wanted to study were various sea conditions, effects of friction and wind, and vibration.

willmer, as i reflect on this brief yet challenging exercise i have still more questions than answers on your project. you have embarked onto a fascinating topic in mechanics of materials and i have especially enjoyed the exchanges with mike johns.

[wellmer]

Now that raw hull building is almost finished i can share pictures and video.

Get a look at Ian's Yacht Sub at:

http://www.youtube.com/watch?v=zLv22CPYFSo



Cheers,

Wil

[harlemriverman]

appears there is some hefty reinforcing steel in the exposed aft section and shell is considerably thicker than 10cm you had proposed earlier, what did you end up doing for a design?

[wellmer]

Originally Posted by harlemriverman

appears there is some hefty reinforcing steel in the exposed aft section and shell is considerably thicker than 10cm you had proposed earlier, what did you end up doing for a design?

This is necessary in case of heavy collision - i want a shaft break before a hull breach. On this hull minimum thickness is 20cm in tail section (sorry - i did not propose 10cm for a 18m hull - that would be less than a third of what i would recommend... even the 20 ton - 10m prototype had thicker walls...)

Cheers,

Wil

[harlemriverman]

what did you end up doing about vibration?

[wellmer]

Originally Posted by harlemriverman

what did you end up doing about vibration?

I do not expect vibration to be an issue in this boat.

Originally Posted by harlemriverman

...loads in ways that do not compliment the strengths of concrete

Concrete in submarine applications up to 1000m depth is well tested, well understood, well documented, and well studied...

Originally Posted by harlemriverman

...load cycle...

Concrete floating structures in marine ambient generally are supposed to take a order of million load cycles per year and have a service life of 100 years. In this conditions cycle load is considered a "non issue"...


Cheers,

Wil

[harlemriverman]

wil, i'm asking questions from the perspective of no knowledge of or experience with concrete submarines. outside of this thread i've never heard of such a thing. certainly opens the door for questions but you're responses are defensive and make little sense. you don't anticipate vibration to be an issue so you ignore it? 100 year service life? come on man, just be genuine. you've case a concrete vessel, that seems real enough, but the way you handle questions and back-track on your own assertions is confusing.

i wish you much success with your project but it doesn't feel like that's where you're headed, not from the way you're communicating anyway.

[wellmer]

Originally Posted by harlemriverman

wil,.... outside of this thread i've never heard of such a thing...

...if you are engineer you should have heard about concrete structures land based and marine ones...i assume...except you are living and thinking in a very small box...i don't see a reason why a sub hull can't be taken as just another structure...the problem seems to be mental - not engineering - in fact a pressure loaded concrete tube under mild cycle load is not really a engineering issue that needs tons of "rocket science tec mec discussion" - The really intersting questions is about practical application in submarine yachting and the best way to pull it off...

Originally Posted by harlemriverman

...responses are defensive...

Excuse me if my responses to attack are defensive...

Originally Posted by harlemriverman

... responses ...make little sense...

They should make sense to a open minded engineer...i get daily feedback from people for which my responses make a LOT of sense...i do not aspire to convince everybody who is out there...this would be a impossible task.

Originally Posted by harlemriverman

..don't anticipate vibration...

I have heard and read about the "vibration issue" on nuke sub due to their building and speed carackteristics - fact is - i do not build a nuke sub, i do not speed like one - so the issue is a NON-issue, it was a non issue in the prototype and it will be a non issue in this boat based on the experience of the prototype. But i will test that out in detail and share the info with you.
Honestly i think the basic problem is still that you seem still mentally entangled in the military sub segment.

Originally Posted by harlemriverman

...100 year service life? come on man...

Yes, please update with the corresponding studies about load cycles on floating concrete structures in severe marine ambient...

Originally Posted by harlemriverman

...the way you handle questions is confusing....

Sorry if i confuse you - i just try to get my project forward - if you are not on board for now that is sad - maybe we make another intent to get you on board a bit later when the boat is out and navigating.



Cheers,

Wil
concretesubmarine.com

[harlemriverman]

i'm niether on board nor not on board wil and my sole wish for you is much success with your project. i'm not challenging or doubting your ambitions either, although i am again taken back by the tone of your postings.

i don't design marine vehicles. i design and build buildings, bridges, etc and aside from the occaisional concrete tank or pier we don't encounter concrete submarines in my world. i simply don't know anything about them. and i found no light in taking some time to model the vessel you had proposed earlier. mathmatically you seem to be headed in the right direction with a thicker envelope and steel reinforcement and again, best of success to you and your project.

[wellmer]

Originally Posted by harlemriverman

i'm niether on board nor not on board wil and my sole wish for you is much success with your project. i'm not challenging or doubting your ambitions either, although i am again taken back by the tone of your postings.

i don't design marine vehicles. i design and build buildings, bridges, etc and aside from the occaisional concrete tank or pier we don't encounter concrete submarines in my world. i simply don't know anything about them. and i found no light in taking some time to model the vessel you had proposed earlier. mathmatically you seem to be headed in the right direction with a thicker envelope and steel reinforcement and again, best of success to you and your project.

Hello Harlemriverman, i am happy that you are still on board. I would ask you to make your mind free of the "concrete submarine idea" for a minute and do what my old physics teacher told me. If you have a appearantly complicated problem - split it down into simple detail problems. A submarine is basicly a submerged tube - OK? So can you think about "pressure loaded concrete tubes" in your engineering world ? When you give me a yes for this i would say - well, how do you calculate the pressure resistance of a tube in the most simple way. As a engineer you would come up with a arch calculation - right? You can imagine a tube as a series of arches. What is the problem that makes the thing complicated - obviously Buckling - so if you make the tube sufficient thick to exclude buckling as "expected failure mode" you get a relative simple calculation where the material compression strength is the determinating factor. Next step you test your simple calc on a series of models in real world to see if the test results supports that idea - you will find they do.
I know that if you look it sufficently detailed the problem can always be "made much more complicated" - but baseline is - a concrete tube with the characteristics i propose - submerged - calculates and models very well with a simple arch calculation that a first semester student can do with paper and pencil in a few minutes and was well understood by roman engineers some 2000 years ago. So there is absolutly no "rocket engineering" in the basics. If i can get a YES for the idea that it "might be structurally possible to submerge a concrete tube" i would like to take you to biology. - the submarine was not invented by the military it was invented 400 million years ago by mother nature.

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

...pressure resistant (imploding at a depth of about 800 m) ...

This little submarine has nothing else than a pressure resistant shell a biological water pump for bouancy control and a basic propulson and steering.

Can we part from the hypothetical approach that ANYTHING a nautilus don´t have but a modern sub has, is basically a "military driven need" that has nothing to do with the requirements of just hang out in the ocean and pass well.

If i could get a YES for this - we could start a interesting dialog about what a "nautilus like leisure boat for human ocupancy" would require.

I would say a hull shape of this kind would be nice:

video concrete submarine hull
http://www.youtube.com/watch?v=zLv22CPYFSo

My current submarine yacht project:



I am working on it...

Cheers,

Wil