Concrete submarine

[wellmer]

The concrete submarine discussion is at:

Submarine Yacht project

By the way i am the guy who builds the 200 tonner i am some 80% done. I am sorry if i left the impression that there is no news... i am just busy - see the basics on

http://concretesubmarine.com

I will publish a report as soon as i am in water...

Cheers,

Wil

[Tcubed]

FASCINATING!

I have been a while reading these and previous threads on the subject.

I have been dreaming about this for years. Ferrocement is an obvious construction material choice for a structure that will be under compression...

I had previously (a few years ago) checked out the internet on this and came to the conclusion that the navy already have highly developed concrete subs and as usual are not talking about it. Please check this out for yourselves, don't take my word for it. I found very strange things when i researched this.

A basic question that i did not notice; do you maintain it by diving and scraping/scrubbing? Antifouling paints get pretty weak after a year. As most of a subs'[ resistance is due to viscous drag, keeping it real slick is imperative.

[wellmer]

I am building the 200 tonner - it will be finished end of year...

Cheers
Wil

[rwatson]

For goodness sake - why would the navy develop concrete subs when they can afford proper steel?

Steel is even better at compression than concrete, and infinitely better in every other way. In fact, without steel, you wont be building concrete subs.

I bet you found some "very strange things" on the internet - they would be very strange to think there was an advantage to a concrete sub.

By all means, throw in a few references you think are usefull.

[Tcubed]

Simple; the prime objective of military subs is invisibilty. Concrete has very different reflectivity to steel.

[wellmer]

Maybe for the same reasons why engineers built TROLL A in concrete (a 300 meter deep diving pressure hull of 24m diameter) - although STATOIL can afford steel - i assume....

See concrete submarine pressure hulls in use as we speak:
http://imulead.com/tolimared/concret...ne/anuncios/ac

Cheers,
Wil

[Tcubed]

<<Steel is even better at compression than concrete, and infinitely better in every other way>>

And by the way, R. Watson, steel is no better than ferrocement at compression when you compare weight for weight.


And I guess that includes the infinite rusting advantage too....

[rwatson]

Originally Posted by Tcubed

Simple; the prime objective of military subs is invisibilty. Concrete has very different reflectivity to steel.

Bullshit - it has to have steel re-inforcing, and steel fittings. They would be better to build it out of fibreglass for true stealth operations.

I know you are building one Wil. We went through all this stuff in depth months ago when you first brought up the topic.

Who will be your insurer when you launch Wil ?

[Tcubed]

Of course it must have tensile reinforcements, but if the wavelength of the detectors is less than the mesh spacing the mesh is essentially transparent.

So save your cussing.

Insurers are an even more conservative lot than engineers; if there aren't enough of them out there to get good statistics on, they will not attempt to guess a risk factor, no matter how safe they may or not be.

[wellmer]

The most important factor is that you can build in concrete in almost ANY hull thickness - the 200 tonner i am building has a 34cm thick hull - have you thought about what building in 34cm thick steel sheet would mean? You just can't do it. Check the fabrication method for alvins new pressure hull to get the picture. Even a inch of sheet thickness is a very difficult task for a shipyard.

Insurance - no insurance for concrete submarines - you know that. Insurance is only available for mainstream shipbuilding - what we do is certainly not mainstream.

Stealth,
I am not sure that concrete would be stealtier than steel, last but not least there are tons of steel in a concrete sub in form of rebar.

Anyhow we will check on that with our friends of the colombian navy. Last thing i would want is to find my tecnology in wrong hands so we work very close with the good guys colombian navy will have it first.

Cheers,

Wil

[Jimbo1490]

My 2 cents:

Military subs have to be able dive deep. Steel is certainly better if you want to dive several hundred feet deep. (although Alvin did it with epoxy and microballons)Titanium is even better than steel which is why the Russians Built the Alpha and Akula of Ti. Both of these subs are known to be capable of diving to impressive depths. Since a simple yachtsman has no need of diving to these depths (to escape depth charges and torpedoes and what not) then it seems to me that steel would be less attractive since it is much costlier to form into a hull because of the need to shape thick steel panels and then execute all those perfect quality welds.

Jimbo

[Tcubed]

Wellmer, i would like to know:
If the interior diameter is kept constant on a bathysphere-say 2 M - does there exist an external diameter to resist the pressure at 11 000 M ?

Suppose a ball of ferrocement 20M outside diameter and 2M inside diameter with steel rod mesh spheres every 20cM ...... i would think that that would withstand even maybe much more than 11 000 M?

And i repeat my Q
A basic question that i did not notice; do you maintain it by diving and scraping/scrubbing? Antifouling paints get pretty weak after a year. As most of a subs' resistance is due to viscous drag, keeping it real slick is imperative.

[rwatson]

Originally Posted by wellmer

The most important factor is that you can build in concrete in almost ANY hull thickness - the 200 tonner i am building has a 34cm thick hull - have you thought about what building in 34cm thick steel sheet would mean? You just can't do it. Check the fabrication method for alvins new pressure hull to get the picture. Even a inch of sheet thickness is a very difficult task for a shipyard.

Insurance - no insurance for concrete submarines - you know that.

Why is thickness of hull a positive factor? It just means that you get less capacity for a specified size. And it cant be insulation for sound or temperature. There are far more effective materials than concrete for that. And as for depth, as you say, you wont be challenging any records in this craft.

And yes , I know you will never get insurance. What the commercial powers will say about 200 tonne of uninsured concrete floating around the shipping lanes of the south pacific, I can only anticipate.

Originally Posted by Tcubed

Of course it must have tensile reinforcements, but if the wavelength of the detectors is less than the mesh spacing the mesh is essentially transparent. So save your cussing.

Oh come on - you think detectors cant cope with a silly difference in wavelength ?

The modern navies of the world have the vibration signature, inferometer (magnetic impulse) and noise characteristics, strategic data on armour and armanent of every class of naval craft (and a huge percentage of individual vessels), and larger commercial craft within 24 hours of them being launched.

As if a bit of a change in wavelength would make any difference ! Electronic detection equipment is a lot more sophisticated than that.

[Tcubed]

In engineering thickness means that it is much easier to resist buckling.

Look into why the "Fram" was built out of oak, not steel, at a time when steel shipbuilding was common and well understood. I looked at the Fram up close myself and it is truly impressive. The thing is, lower density materials can be built to greater thicknesses and get better compression stress to mass ratios.

Yes it is true that it eats up internal volume, but typically it is in the small fractions.

[blackdaisies]

They are probably using the concrete in the Navy for cheap civilian type boats or Uboats. They may use them openly for ocean research, but use the metals for battle ships? They are popular world wide, so if other militaries are using them, why not the US?

The boats have to be x-rayed by a surveyor because of the metal in the concrete rusting. If it rusts, the boat will fall to pieces. That's what I've read anyways. That might only apply to surveys to sell the boat