Destroyer Replacement Program

[drunknsubmrnr]

Launched from 20,000 metres, an 80 knot wire-guided torpedo would take 8 minutes to reach its target, from 5000 metres at 45 knots for a simple torpedo about three and a half minutes.  In an age of long range sensors and weapons that is a very long time, more than enough for a VLS supercavitating depth charge armed vessel to destroy both the torpedos and/or pre-terminal guidance wires and the launching submarine.  There have been unconfirmed reports of Russian SSBN's being armed with such weapons in addition to the advanced prototypes known to exist; this weapon would have little likely purpose other than anti-torpedo defence.  There was reportedly even an unsuccessful Canadian attempt some years back to actually try to covertly buy one of these weapons.

Generally you'll see torpedoes fired at very short ranges. There isn't a whole lot of time for counterfire of any type, supercavitating or otherwise.

Tirpitz did not conduct short sea trials half a year after the X-submarine attack by being towed to sea by tugs. 

No, but she had to be towed back. At that point, the Germans gave up on the battleship plan and went to floating battery. The shock damage to the machinery was simply too difficult to repair with the resources they had.

The RAF resumed attacks because it was operationally ready again regardless of outstanding distortions and stress damage to the hull.  Being moved around by tugs occurred during a brief period two months before it was finally sunk.

I think you're confusing what the RAF thought the Germans were doing and what the Germans actually were doing. It came out after the war that the Tirpitz was going to be converted to a floating battery after the X-craft attack.

The on-going pattern of presenting exaggerated or simply incorrect arguments while at the same time offering no indication of any position of your own suggests only one thing.  You have an agenda.

If I've offended, my apologies. I haven't been pushing an agenda, I've simply pointed out some flaws. Your ideas are certainly worth looking at, and thank you for posting them.

 

[a_majoor]

Since I floated the battlecruiser idea, I should weigh in as well.

I am not a sailor, but rather an Infantryman, so my interest in ships is mostly theoretical. The "Big Honking Ship" is probably the only naval vessel that I could ever have direct contact or experience with (assuming they build one really soon  ), surface combatants and submarines would be off in the distance making sure me and by buddies actually arrive.

The 20,000 ton hull was based on the observation that large vessels have taken damage and continued to sail during the tanker war, along with the corresponding observation of smaller surface combatants getting taken out of action with one hit from an iron bomb or anti ship missile or even smaller weapons. Soviet era submarines were also reputed to be hard to kill due to their double hull construction with spacing measured in metres. This write up of an event during the Falkland Islands war is illuminating:

Marine David Combes, who was normally the ships steward on Endurance now placed his name in naval history books by firing his Carl Gustav 84 mm anti tank weapon at the Guerrico.  The Royal Marines watched as the 10lb projectile staggered across the waves and then, on it's last legs, smashed into Guerrico's hull just above the waterline, sending up a column of white water.  They then heard a loud rumble come from inside the ship. Below decks Argentine damage control parties struggled to stop the flow of water that was now coming though the hole.

The explosion killed one Argentine sailor and wounded several others. It also destroyed many electrical cables, including the ones used to power the 100 mm gun's traverse mechanism making the gun useless at this close range. The aft 40 mm was still working until Marines Parsons and Chubb cut down the Argentine gun crew with their LMG. Alfonso was having a hard time trying to manoeuvre the big ship quickly inside the small bay. He knew he had to get out of the bay quickly. As the ship came about, Sergeant Major Leach lying on a table up stairs in Shackleton House, took his time and fired 15 shots into the bridge with his sniper rifle. This caused panic and confusion as officers and sailors trying to steer the ship had to take cover. With the ship turned,  Alfonso steered the ship out of the bay, but she had to run the gauntlet of fire from the Royal Marines again before getting out of range. Marine Combes let go another 84 mm at the frigate that smashed into the hull below the Exocets. The Marines also managed to hit Guerrico at least twice with 66 mm rockets. Corporal Peters was severely wounded in the arm while standing to fire his 66 mm. The rifle shot had come from one of the Argentine Marines in the buildings near Shackleton House.

So a large hull using lots of spacing and widely separated and isolated modules seemed to be one way to save the ship and keep it in action even if the inevitable leak through happened. The only other way a battlecruiser would be viable would be to go to WWII era design and install a nice thick armour belt. The ship would be much more compact, but I can't see that really overcoming the objections that people with experience in these matters have raised.

I floated a thought experiment, and it sank. I'm sure I'll think of something else...........................

 

[DONT_PANIC]

So a large hull using lots of spacing and widely separated and isolated modules seemed to be one way to save the ship and keep it in action even if the inevitable leak through happened. The only other way a battlecruiser would be viable would be to go to WWII era design and install a nice thick armour belt. The ship would be much more compact, but I can't see that really overcoming the objections that people with experience in these matters have raised.

The trouble with heavily armoured battleships is that they are still vulnerable to torpedoes, which strike below the waterline of the ship.  When submarine scares hit the Royal Navy in the early 1900s, there were a nubmer of attempts to "torpedo proof" ships.  The attempt ended with the "torpedo proof" battleship (already paid off) being sunk on the first shot in the middle of the harbour.  I think that I had found that ianecdote n a more recent book on Sir Jacky Fisher.  If anyone really cares, I can dig up a citation.

 

[T.S.Rea]

As per posts three/four up:

It was tone that I was talking issue with.  Often the remarks I have made have numerous underlying assumptions being made concerning them, and regardless of that there would remain some basic weaknesses or deficiencies as applied in practice.  Despite the degree of care taken to review something over and over again in search of showstoppers, there can remain a particular problem which was never anticipated at all.  It is the fatal flaws that I look for most of all, since obviously could means nothing if you can't.

You would have to read through some of my own remarks carefully (assuming one has the time to go to this trouble), since often innocuous looking remarks are a very condensed summary of a larger issue.  In many cases, it really is not the case for doing something a particular way because of one advantage, but that if it is being done that way to meet several other basic demands, that there are is an advantage to be had to improving something else in the process.

I consciously try to avoid viewing things in black and white, and if it is perceived that I 'know it all', then the perception is far from the reality.

Actually, there were a number of points raised by drunknsubmrnr that gave me pause to re-evaluate certain aspects of my own opinions.  I was aware of the issues, but that should not be a reason to not scrutinize them yet again.



Reply to subsequent post by drunknsubmrnr:

My apologies, looking for a more constructive discussion in the future.

The discussion of anti-torpedo weapons were hypothetically in the future, there obviously being no such equipment available now.  Relative to analogous long range and close-in anti-air defences there is more time to react, but I find it unlikely they would be availabe for CF service for ten or even twenty years in the future, and possibly never.  Apart from countermeasures, that leaves only passive means as a defence against the rare but still dangerous prospect of torpedo attack.

Torpedo resistance is not the reason for a large hull vessel, it is something that could be exploited to advantage since the hull would have to be large simply to conduct operations at distances of many thousands of miles from port and project any significant size of force on to the land or alternately to conduct sea control operations in distant waters that would require auxilliary support in most instances regardless.

Like body armour it would not be impervious to attack, but relative to the value of everything else, worth the moderate trouble of putting it into practice.  Most loss of life on a warship occurs when the vessel is sunk quickly, casualties almost always being lower if the ship can be kept afloat.  The large ship may still have to be scuttled, it may divert resources away from the task group, it may have to be beached somewhere for later salvage, or it could limp back to home port only for it to be decided that it is not worth repair, but those are financial and strategic
decisions to be made long after the fact.  With the smaller vessel it is forgone conclusion that it is a complete loss to a torpedo attack.

----------

Tirpitz was heavily damaged by the x-boats.  Lifted a foot or two up, the ends of the ship whipped back and forth like a gigantic tuning fork, it certainly did suffer massive damage to its engineering plant and stress fractures and damage throughout the hull.  It was never fully repaired, not the least of reasons was its isolation in a fiord above the Arctic circle far from any accessible major shipyard that could repair the ship.

The brief sea trials half a year later to test the part of the machinery plant that was repaired appears to have prompted a renewal of air attacks, since it would have been apparent that the ship was no longer completely out of action even if the RAF did not know the ship was barely functional.

The disagreement is one of degree.  It was a loss as a combat ship for the rest of its service, but it was not sunk in the x-boat attack and could have been repaired if it was practical and a priority.

 

[drunknsubmrnr]

No apologies necessary. We're all trying to find the right way to go about things, and the 'Net doesn't transmit a lot of subleties.

The problems behind active anti-torpedo defence are mainly rooted in sound transmission speeds through water. For one thing the speed of sound in water is variable, leading to the situation where sound doesn't travel in a straight line in water. You need to saturate an area with sensors in order to calculate exactly what the sound path would be, and where an incoming torpedo or interceptor is. For another thing, the speed of sound in water is a lot slower than in air, leading to a very slow active update rate, which makes interception difficult.

For both reasons, I'd say a torpedo interception system would be at least an order of magnitude more difficult to come up with than Aegis, and even more expensive than that.

I agree with you that a large vessel is the way to go here. It would be both more damage resistant and possibly even remove the need for an AOR.

For the Tirpitz, I agree with you that we're just discussing degree of damage. It may be that Gneisenau's damage by the RAF may have influenced their decision in not repairing the ship. Knowing that even if you get him back he may just be bombed out in dry dock would tend to put a crimp on any plans to do so.

 

[Bane]

The problems behind active anti-torpedo defence are mainly rooted in sound transmission speeds through water. For one thing the speed of sound in water is variable, leading to the situation where sound doesn't travel in a straight line in water. You need to saturate an area with sensors in order to calculate exactly what the sound path would be, and where an incoming torpedo or interceptor is. For another thing, the speed of sound in water is a lot slower than in air, leading to a very slow active update rate, which makes interception difficult.
For both reasons, I'd say a torpedo interception system would be at least an order of magnitude more difficult to come up with than Aegis, and even more expensive than that.

Stop.
In fresh water, sound travels at about 1427 m/s at 5 °C
In air at 0 °C at sea level the speed is about 331.3 m/s
The more dense the material, the FASTER sounds travels...this is why you stick your ear to the track to hear a train in the distance; the vibrations travel faster and further.  Because of that your 'update rate', whatever that is, would be way better.
Also...
The speed of sound in water very consistant at a given tempurature and salination.  You may have issues with currents (at very long range) and waves as background noise but that is a different issue.  Also, you need massive tempurature changes to make any significant change in the speed, on the order of which would never be found in nature on the ranges you are talking about.

I don't know what the hell Aegis is but i'm going to assume that you are wrong about that too.

 

[drunknsubmrnr]

In fresh water, sound travels at about 1427 m/s at 5 °C
In air at 0 °C at sea level the speed is about 331.3 m/s

My bad...it's the speed of sound in water vs the speed of light in air.

Aegis is a naval radar-based misile/aircraft defence system. Basically the same as what TS Rea described, but it works against missiles/aircraft rather than torpedoes. The speed of sound in water is a LOT less than that of light in air, implying it takes a lot longer for a signal to get to the target and return. That round-trip frequency is the "update rate". The update rate affects not only your appreciation of where the target is, but also where you can predict it will be. The slower the update rate, the larger the error in the target position. The larger the error in target position, the less accurate the interception. OK?

The speed of sound in water very consistant at a given tempurature and salination. 

Quite true. However, temperature and salinity are sufficiently variable to grossly distort the predicted sound path unless a LOT of samples are taken. If you can't predict the sound path, you can't predict the target position.

You may have issues with currents (at very long range) and waves as background noise but that is a different issue. 

Actually, the current issue is usually found with changes in salinity due to fresh water mixing with salt. There are currents which are significantly warmer or colder than their surroundings, but they're not as bad.

Also, you need massive tempurature changes to make any significant change in the speed, on the order of which would never be found in nature on the ranges you are talking about.

You're thinking 2D only. Torpedoes work in 3D....Seawater temps change a lot over just a couple of hundred metres.

 

[T.S.Rea]

Targeting would be the great problem with intercepting a torpedo, since it would have to get in quite close to cripple the weapon if not destroy it at short range or else it would likely keep coming.  Off board acoustics, blue 459nm wavelength active sensing, and other possible sensor types all would have problems operating effectively under real conditions at sea with the further complication of relatively simple active countermeasures that could be employed on the torpedo.  And once you start to use multiple methods of targeting and homing, reliability will drop since everything depends on an extended chain of events all working perfectly, and cost will go up because of the this as well.

Realistically, I can't see even a remote chance this being considered in Canada, only the USN would have the resources for something of this nature, which given the rarity in the last several decades of torpedo attack would not likely see anything enter service for a long time to come.   Supercavitating weapons would more likely see initial service as a shallow water INS depth charge against submarines in situations where homing torpedos would be difficult to use (or not fast enough in some situations without active homing), their value likely being borderline given the cost of adding another weapon type to the arsenal relative to possible improvements to the lighter outfit of small torpedos.  Off hand, I would not know what the specific limitations of acoustic homing torpedos in shallow waters actually are at present since the information would be heavily classified, but it is not difficult to recognize that there are limitations.  As to how effective a SC weapon would be as a close in defence would all depend on the specifics of the systems involved, and even that would not be very easy or inexpensive or else such defensive measures would probably already be in place.

The theoretical possibility would likely have to be driven by an actual increase in torpedo attacks, since you would have to ask yourself if it would not make more sense to be spending limited defence dollars on more immediate priorities across the range of military needs.  Trying to mitigate some of the damage they can cause probably would be the only realistic option in the near term.  The active layer of defence may or may not come at a later date depending on the priority over the cost.  Passive defence might also have a limited indirect effect of discouraging torpedo attack, since the risk works both ways and it is not reasonable to assume many would want to attrite themselves outside of overwhelmingly greater reasons for it (may be why they have been rare recently?).

How difficult from theory to practice for various levels of capability would be difficult to make a reasonable guess without a full technical study, could easily be fall somewhere between anti-air defences and intercepting a ballistic missile in practice.  Although it has become increasingly more commonplace in recent times to put a premium on lives, I always have used that standard since I might have been in the service and implicitly put myself in that situation by default.  Even neglecting the ethics, it just makes more plain military sense as well.

 

[drunknsubmrnr]

I did think of a situation where supercavitating projectiles could make a short-term difference. There's a USN program call RApid MIneClearing System (RAMICS) that fires supercavitating projectiles at mines. There's also a requirement for something that will discern the difference between a possible submarine contact and a definite submarine contact. That's usually done by dropping something on the contact and seeing if it does anything. Maybe an enlarged version of RAMICS could do that.

How difficult from theory to practice for various levels of capability would be difficult to make a reasonable guess without a full technical study, could easily be fall somewhere between anti-air defences and intercepting a ballistic missile in practice.  Although it has become increasingly more commonplace in recent times to put a premium on lives, I always have used that standard since I might have been in the service and implicitly put myself in that situation by default.  Even neglecting the ethics, it just makes more plain military sense as well.

I agree with your point on ethics.

Incidentally, missile defence is generally easier than air defence. Did you intend it to read that way?

 

[SeaKingTacco]

The speed of sound in water very consistant at a given tempurature and salination.  You may have issues with currents (at very long range) and waves as background noise but that is a different issue.  Also, you need massive tempurature changes to make any significant change in the speed, on the order of which would never be found in nature on the ranges you are talking about.

Bane,  you have absolutely no experience with active sonar against a submarine target, do you?  I assure you, it is no where near as simple as you think to determine the ray path of sound through water.  It is as much art as it is science.  The speed of sound in water, in real life, is affected primarily by salinity, temperature and depth of water.  It can be further influenced by factors such as the type of bottom environment and even what kind of weather is happening.  There are rules of thumb that help Sonar Operators get the right depth for the sonar to find and track a submarine, but one can never know the depth of his target with any certainty.  Only bearing and range.

It should also be pointed out that sound energy is very quickly attenuated in water, giving very short ranges (relatively speaking).  Unless you are willing to pour massive amounts of sonar energy into the water (and kill every whale within 50NM), there are limits to what can be done with sonar.

I for one would not hold out much hope for an active torpedo defence system.  I feel the money is better spent on quieting the platform.  And good tactics.  And lots of helos with aggressive crews. 

 

[a_majoor]

Supercavitating weapons are still something of an unknown. The Shkval was reputed to have been developed as a last ditch point defense weapon for Soviet era SSBN's, allowing the commander to fire at the oncoming American/NATO torpedo and either destroying the torpedo, causing the launching submarine to cut the torpedo loose and attempt to escape, or (best case) hit the enemy submarine.

It has now appeared in other navies, and seems to have been adopted as a means for diesel electric submarines to perform entry denial, or at least seem a lot scarier than they already are. Certainly the idea of dodging a torpedo moving at 300kph or more is on the very outside edge of possibility, and in theory, a supercavitating projectile can move at supersonic speeds under water. (New Scientist magazine, 22 July 2000). To date, no one seems to have solved issues like guidance or increasing range.

A torpedo defense based on these weapons would probably resemble an "inverted" air defense system, with a volley of small Shkval type torpedoes being launched in the direction of the incoming, and the CIWS firing down into the water with supercavitating bullets. It would look pretty spectacular ("Rocket Torpedoes Away!!!!), but given accurate location of the incoming is so difficult, I think the end result would be a very expensive system with a very low Pk.

 

[T.S.Rea]

There probably would be merit to the cost of working on various types of SC projectiles regardless of applying it to a full size weapon.  I don't recall off hand having heard of the RAMICs projectile before, but it makes obvious sense given the tedious task of otherwise putting demolition charges on mines.  The same thing gets done with 0.50 calibre machineguns, there was even a development project long ago to mount several of the machineguns on an armoured vehicle to sweep a path in front of it to clear a lane through minefields (I think it was cancelled primarily because of the cost of all the bullets and some minor technical issues relative to the more destructive method of using line charges or plows).  Improving the design simplicity and the efficiency of the laminar flow of the SC bubble on less expensive smaller delivery bodies with more immediate uses would open up a lot of other potential applications and make it easier to develop less expensive full size SC weapons.  As you mentioned, the intermediate stage of sensor/probing packages to rapidly confirm a submarine target would be one such application that would avoid expending much heavier and expensive weaponry on it and conserve a limited arsenal by avoiding killing marine life or anything thing else that could be mistaken for a submarine when there is little time for the debating society to hold a session and render its full report of recommendations before the sitting of the upper and lower houses of the board of governors (a reaction would probably confirm whatever it might be, a non-reaction might allow subsequent investigation but might not disqualify it as a threat depending on what is actually being used to interrogate the possible target).  A further use of smaller SC delivery bodies could also be to rapidly deploy stand-off countermeasures to act like the equivalent of a smokescreen/flare/chaff cloud under the surface over a broad volume of water.

 

[drunknsubmrnr]

To date, no one seems to have solved issues like guidance or increasing range.

To their credit, the Soviets did get around the guidance issue. They tipped the torpedo with a nuclear warhead. Raised Pk to very near 2.0.