Concrete Submarines??!

[Cap'n Refsmmat]

I read an article in Popular Mechanics a few years ago. It had this idea. What do you think of it?

 

You'd have a submarine who's hull is made of concrete. Yes, concrete. It's supposed to withstand greater depths (when it's a foot thick) and it's supposed to be cheaper than a steel hull of the same strength. The idea is to have a concrete submarine that will float out and sink onto the seafloor, and just wait for months until someone goes overhead. Then you vertically launch a torpedo at them.

To get to its station, it would need to float. A concrete sub with a hull this thick probably wouldn't float very well, so you'd have turbines mounted vertically to hold it up.

 

What do you think of the idea?

[LucidDreamer]

It doesn't sound like a winner to me. It would be pretty much immobile. It could defend a certain area but if the enemy located you, which is likely, they could just drop a bomb on you and you couldn't avoid it. I could see this idea working well as an underwater sea lab that could withstand the deeper water pressures and relocate when it needed to.

[Aeschylus]

When I was a child going down to the River Meadway in Gillingham, I seem to remeber that they had concrete boats beached near the harbour down there.

[Cap'n Refsmmat]

How the heck could they detect you? A modern US submarine can't be detected at any speed under maybe 7 knots and over 2000 yards. They're quiet enough. And you wouldn't go around using active sonar that would alert them, since they'd blend in with the sea bottom and they could detect your sonar before the return signal gets strong enough for you to see them. Then they could blast you with a torpedo.

[atinymonkey]

You'd have a submarine who's hull is made of concrete. Yes' date=' concrete. It's supposed to withstand greater depths (when it's a foot thick) and it's supposed to be cheaper than a steel hull of the same strength. The idea is to have a concrete submarine that will float out and sink onto the seafloor, and just wait for months until someone goes overhead. Then you vertically launch a torpedo at them.[/quote']

 

Yeh, the full story is here:-

 

http://www.popularmechanics.com/science/military/1998/12/concrete_submarines/

 

It may be possible to build small 6 man subs, but anything larger will have problems moving. I also have a suspition that the concrete lacks the flexability at depth that a sub requires to withstand the pressure.

 

Aside from all that, the boat would have to have large motors that make a lot of noise. A boat would hear it coming a mile off, and that makes it hard to hide a sub in a place where a boat is guaranteed to pass over.

 

I think LucidDreamer is right, this technology would be better for sea labs. It would save a packet on development costs. It could even be moved by a dredger, to save on installing motors.

 

When I was a child going down to the River Meadway in Gillingham, I seem to remeber that they had concrete boats beached near the harbour down there.

 

They are quite an old technology in the UK:-

 

http://www.ferroboats.com/

 

I think I've been on board one, but I don't really remember much about it. It was used in the arctic for surveys, the concrete was a safer option than steel in the sub zero environment.

 

How the heck could they detect you? A modern US submarine can't be detected at any speed under maybe 7 knots and over 2000 yards.

 

We have the technology to detect 400 year old shipwrecks at the sea bottom. We can even identify individual cannon, part buried in the sand. What the system looks for is regular shapes on the seabed directly around the boat. The system is simple, if it isn't a fish or a rock it flags it up.

 

What they mean when they say modern subs are not detectable is that a frigate equipped with tracking equipment could not track down a Sub in the sea based on the noise it made. All the sub needs to do is stay out of it's 'line of sight' to stay invisible. It's a huge ocean, and it's quite easy not to sail anywhere near another vessel for months while at sea. However, if the sub was stupid enough to sail under the bow of the ship it would be detected before it approached 400 yards.

[5614]

wouldnt be very nice living in a concrete sub, you'd have to stay in there for ages;

 

it would be immobile

 

it would have no defence, if [unlikely] someone found it.

 

it's just not a very good military idea, however it does have possibilities for other underwater research.

[YT2095]

sounds like an underwater version of a "pill box" )

[5614]

nice one

 

still has potential though (in that it can withstand pressure)

[Cap'n Refsmmat]

Wait!

You obviously don't understand submarines very well.

This would sit in a fixed position on the bottom. Its reactor wouldn't even need any pumps running, since no motors need to run and the coolant can circulate by convection. Therefore it would be nearly silent. Next, that extra-accurate sonar is not effective at as long a range as it could be. You can hear the pings before they bounce back strong enough for a ship to see you. So you could easily tell they were coming. Then you just vertical-launch a torpedo and BAM! no more ship!

It would be a great and cheap defensive weapon.

[atinymonkey]

Ok, for a moment I'll forget what I know about boats and radar. I'll pretend for a while that I've never used either. Lets assume that the Navy is rather poor at monitoring underwater acoustics. What is the advantage of placing a manned submarine over, say, a sea mine?

[Cap'n Refsmmat]

A manned submarine can pick its target and choose what to blow up. It also can blow things up more than once. It can be deactivated. It can choose between friendly ships and enemy ships.

The list goes on.

Look, even SOSUS can't detect a Kilo diesel electric sub when it's running slowly on electric motors. Who would say that it could detect a submarine that is not even moving at all?

[atinymonkey]

Actually, that was an honest question. It came across a bit sarcastic because I was a bit preoccupied.

 

It's a good answer.

[badchad]

From what I know, submarines are most easily detected by their soundwaves. I assume it's because some of the properties of water allow sound waves to carry very easily. While the sub may run quietly, I would think launching a torpedo would create a large amount of noise which is very easily located.

[Cap'n Refsmmat]

The major noise comes from flooding the torpedo tubes with water and then expelling the torpedo with compressed air. I'm sure you could have the tubes flooded beforehand, and have the torpedo shot with springs or something.

[jordan]

Would there ever be a time when the submarine would have to resist firing from fear of the now destoyed ship sinking and landing on the immobile submarine?

[Cap'n Refsmmat]

Well, apart from the fact that it's pretty unlikely that a ship would go directly over them, can't you wait until it starts to pass until you blast it?

[jordan]

I guess that depends on how deep you are. The further under the water you sub is, the more the ship can move from where it began to sink to where it hit the ocean floor. Didn't the two sections of the Titanic end up around 1/4 of a mile apart or so?

[swansont]

It would be a great and cheap defensive weapon.

 

I'm sure that's what they said about the Maginot line.

[Cap'n Refsmmat]

Yes, that's true. The ship still has momentum, so it'll end up a long way from where you first hit it.

[coquina]

A sub's hull does have to be quite flexible. I was on a nuke sub last spring doing some consultant work. The officer that was showing me around said that if you tie a robe from one side of the hull to the other, so that it is taught when the sub is a the surface, the rope will lie on the deck at max depth. He said this demonstration is done for the benefit of new crewmen.

 

He also said that when the dog the hatches at the surface, the bolts are loose at depth. An inexperienced crewman tightened the bolts, and when the sub surfaced they couldn't open the hatch. So - concrete wouldn't flex enough - it would break.

 

That being said - why call the thing a "submarine" if it's going to be stationery? Why not just tow it out to sea and sink it? Use it in the same fashion the international space station is used - ferry crewmen back and forth in small subs.

 

The benefit I foresee would be in allowing deep ocean research for long periods of time.

[Sayonara]

Would the shockwave from the torpedo not damage the concrete hull if it were too close?

[YT2095]

what I don`t understand is that if these things are little more than underwater missile silos, why go they need to be manned?

 

I`ll certainly go with Coquinas statement though "The benefit I foresee would be in allowing deep ocean research for long periods of time."

 

that reads like a sound proposition, at least that`s a good reason for it to be manned

[RICHARDBATTY]

Make a hole in a rock, hide an inteligent missile in it. No thats just what they will be expecting us to do. Make a dumb balloon with a smart box attached containing a slightly inteligent rock to drop on them.

[RICHARDBATTY]

How long would it remain in the same position on the see bed. I saw a program once about retired ships that were sunk to create an artificial reef. It only took a few weeks for an awfull lot of marine life to cover them. I know it would be deep and there is less life down there but might this cause a problem.

[Cap'n Refsmmat]

Okay, I'd like to know: Why does it have to be able to expand and contract?

 

Next, it has to be manned. It's not practical to string a humoungous cable to feed sonar data to humans so they can tell whether or not to shoot. Radio doesn't work at depths, except at low frequency and low speed. Too slow for that type of data.