# South Korea's Daewoo to build fourth 1,800 ton submarine



## CougarKing (20 Dec 2008)

And the ROKN continues to grow. 



> *Daewoo to Build 4th 1,800-ton Submarine*
> By Jung Sung-ki
> Staff Reporter
> 
> ...


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## tomahawk6 (20 Dec 2008)

Maybe we can get them to make the Taiwan subs ?


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## CougarKing (20 Dec 2008)

tomahawk6 said:
			
		

> Maybe we can get them to make the Taiwan subs ?



Nice idea. However, this is impractical considering that both the ROK and Germany recognize Beijing as the one China. And there is a lot of investment by both South Korean and German companies in the mainland; even if both countries also trade with Taiwan, the investments in Taiwan still pale in comparison to those in the PRC. Make Beijing angry and you might not see any more new VW Boras (the PRC version of the Jetta that I remember from seeing there, IIRC) being sold there.


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## sm1lodon (10 Jan 2009)

Since submarines have the outer, or "pressure" hull, made of titanium to alleviate budgetary surpluses, (or reduce weight and eliminate corrosion woes) and then an inner hull to house the submariners and their equipment, and since said subs have a given depth (about triple what they tell you, I'm guessing) to which they can descend, why not have triple-hull subs with an outer pressure hull, and intermediate pressure hull, and an inside hull so that the pressure difference between the crew space and outside could be less extreme across the thickness of one pressure hull?

Or would it be just as effective to double the thickness of the pressure hull? I know that there is a tradeoff between mass, speed, etc. but wouldn't great stealth be achieved by being able to sit on the bottom, under any thermal layer, and just sulk (or loiter, but loiter is more of a mid-air or mid-water term, to me) and be almost completely invisible?

And, again, please, before anyone jumps up and claims that I have no right to say this because I am not the lead engineer designing every nuclear sub in the world, I have a long track record of coming up with technological innovations, showing them to interested parties, then seeing them come out with them years later. (Didn't have the money to patent them.) Another benefit of greater depth is reduced potential for propellor cavitation at any given level of power output.

Yes, yes, I know, they are designed not to cavitate, but it is never the case that greater depth does anything but reduce the chance of cavitation, even on a minute level, from occurring.

Oh, and yes, I also know that cavitation is actually the formation of a vapor of whatever liquid is in question, usually, but not always due to the passage of a body through the liquid medium at a speed that, for a given pressure and temperature, creates a pocket of vapor due to that area being, locally, above its boiling point for that pressure and temperature. And that aeration is when a propellor sucks air in from the nearest pocket or area of air, such as being too close to the surface, and is not to be confused with cavitation.


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## Michael OLeary (10 Jan 2009)

sm1lodon said:
			
		

> Since submarines have the outer, or "pressure" hull, made of titanium to alleviate budgetary surpluses, (or reduce weight and eliminate corrosion woes) and then an inner hull to house the submariners and their equipment, and since said subs have a given depth (about triple what they tell you, I'm guessing) to which they can descend, why not have triple-hull subs with an outer pressure hull, and intermediate pressure hull, and an inside hull so that the pressure difference between the crew space and outside could be less extreme across the thickness of one pressure hull?



Uh, isn't the inner hull that houses the submariners the pressure hull?



			
				sm1lodon said:
			
		

> And, again, please, before anyone jumps up and claims that I have no right to say this because I am not the lead engineer designing every nuclear sub in the world, I have a long track record of coming up with technological innovations, showing them to interested parties, then seeing them come out with them years later. (Didn't have the money to patent them.) Another benefit of greater depth is reduced potential for propellor cavitation at any given level of power output.e nearest pocket or area of air, such as being too close to the surface, and is not to be confused with cavitation.



Have you applied your "long track record of coming up with technological innovations" to determining what extra requirements would be needed to control two different pressure zones to add an intermediate pressure hull and the necessary doubling of all of the related systems?  How about the extra piping, pumps, controls, plus redundancy, etc., etc.,? What about the space requirements, additional costs and crew demands?


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## aesop081 (10 Jan 2009)

sm1lodon said:
			
		

> I have a long track record of coming up with technological innovations, showing them to interested parties, then seeing them come out with them years later.




I have a long track record of chassing submarines. You ideas may make sense from an engineering standpoint but they dont from a tactics perspective. Thats the problem with you engineer types.


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## sm1lodon (11 Jan 2009)

Michael O`Leary said:
			
		

> Uh, isn't the inner hull that houses the submariners the pressure hull?



Wouldn't surprise me.  



			
				Michael O`Leary said:
			
		

> Have you applied your "long track record of coming up with technological innovations" to determining what extra requirements would be needed to control two different pressure zones to add an intermediate pressure hull and the necessary doubling of all of the related systems?  How about the extra piping, pumps, controls, plus redundancy, etc., etc.,? What about the space requirements, additional costs and crew demands?
> 
> No, and I think that would be the killing point of the whole thing. Having to silently maintain your pressures.



It is refreshing that no one bothered to attack my family background, possible tree-swinging lineage, etc. because they don't agree. Not used to THAT on the internet, THAT is for sure.

Another thing I wondered, since low mass and high rigidity are desirable, why not employ carbon fibre? Granted, it is kind of "all or nothing" in the strength department, as in, it is ultra-rigid up until it completely and catastrophically fails, but I imagine that the mass of hull for a given pressure resistance with carbon (or SOME) fibre would be vastly lighter than any metal, as with the fiber-wound N2O tanks people use in their cars.

And, I know that a submarine is not an N2O tank, etc. but, the principle is the same, and those tanks take pretty high pressures and are very light in weight.


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## sm1lodon (11 Jan 2009)

Well, to me, it is an unjust criticism to say "that is the problem with you engineer types."

It presupposes that we, as opposed to you, actually HAVE a problem.

It also presupposes that we have one problem, one only. No others. None. I know it's a figure of speech. So is "you are a complete moron." It isn't literally true. This does not make it less annoying, though.

My response, from long experience with some "practical experience types" is that they can be mousetrap-quick to completely dismiss an idea out of hand, without even CONSIDERING working through the details.

The problem at which I am currently aiming is maximizing submarine working depth. Granted the noise and complexity of having twin hulls inside an outer one is excessive, as you (plural) have demonstrated.

I think that composites will make their way into submarine design in larger and larger degrees as they continue to be proven and moved further towards perfection in other applications, just like carbon fibre parts in airplane wings.

I also foresee more armor coverage for the average soldier that is lighter in weight than at present. I foresee more than that, and I sent it to DARPA with some other stuff. What the heck. Sometimes people can get so bogged in the details they don't look at the forest.


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## Michael OLeary (11 Jan 2009)

sm1lodon said:
			
		

> Another thing I wondered, since low mass and high rigidity are desirable, why not employ carbon fibre? Granted, it is kind of "all or nothing" in the strength department, as in, it is ultra-rigid up until it completely and catastrophically fails, but I imagine that the mass of hull for a given pressure resistance with carbon (or SOME) fibre would be vastly lighter than any metal, as with the fiber-wound N2O tanks people use in their cars.
> 
> And, I know that a submarine is not an N2O tank, etc. but, the principle is the same, and those tanks take pretty high pressures and are very light in weight.



An N2O tank, or other pressurized gas storage tank, is designed to be a closed vessel with only one opening in a reinforced end.  Think for a minute how many points of broken integrity are in the pressure hull of a submarine.  Conning tower, torpedo tubes, pipes, pipes and more pipes (for water, fuel, control systems conduits).  Any "shell" used as a submarine pressure tank must be solid enough to withstand pressures at depth with all of these "holes" as well as be strong enough to sustain all of the internal and external mountings of bulkheads, etc.  Sometimes the question is more complicated than simple vessel (hull material) strength, there are also the other factors of what the vessel (hull) must achieve to serve its full purpose.

The principles are actually very different.

And, in this case, reducing weight is not necessarily the preferred option.  Submarines are designed to sink once their ballast tanks are filled.  A lighter hull system would mean even more ballast tank requirements and there could be a critical point where a lighter hull is counter-productive to the question of the submarine's buoyancy.


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## aesop081 (11 Jan 2009)

sm1lodon said:
			
		

> My response, from long experience with some "practical experience types" is that they can be mousetrap-quick to completely dismiss an idea out of hand, without even CONSIDERING working through the details.



I'm not dismissing you ideas just telling you that you fail to account the tactical aspects. You can make a submarine able to dive deepr if you want but you dont realize the tactical implications of this for the submarine who is trying to accomplish its mission. Its far more complicated that "staying below a thermal layer and sulking" as ASW forces have ways of countering that and "sulking" at the bottom doesnt allow a submarine to accomplish much other than "sulking at the bottom"


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