Friday, August 4, 2017

Time Stands Still

Time Stands Still !

We have witnessed phenomenal advances in military technology since WWII.

  • Aircraft are jet powered and can now supercruise at Mach+ speeds.
  • Weapons can now be precisely guided by lasers.
  • Missiles can home in on their targets using a variety of technologies.
  • Radar can see a mosquito at 200 nm.
  • Stealth ships and aircraft can evade radar.
  • Cruise missiles can travel a thousand miles and hit a pinpoint target.
  • Infrared sensors allow us to see in the dark.
  • Shaped charge warheads can achieve amazing penetrations.
  • Sensors and weapons can be networked to achieve leaps in efficiency.
  • And so on …

The advances in military technology are absolutely stunning.  Most impressive is the fact that the advances have been steady and show no sign of abating.  Not a decade has gone by in aircraft, weapons, and sensor development that has not seen a significant leap in technology.  We can now realistically envision lasers and rail guns.  Star Wars is just around the corner.

As an example, just consider the advances in ship’s armor since WWII.  We’ve developed … uh … new, uh … Boy, I’m drawing a blank on any new advance in ship’s armor.  But, that aside, our ships are now constructed with steel plate that is markedly stronger than … no, wait … Now that I think about it, ship’s plate is actually thinner and weaker than standard WWII hull plating.  I guess we’ve actually gone backward a bit.  Can that be?

It would appear that naval armor development has been mired in a time warp where time has stopped.

Hang on.  Let me make a quick call to the Navy’s engineers.   ………..

Well, that just confirmed it.  I asked them what year it is and they said 1946.  That explains the utter lack of progress in naval armor.

It’s funny.  When we discuss aircraft, weapons, and sensors, it’s always in the future tense.  This next generation of aircraft will have weapons that …  and sensors that will …

But, when we talk about naval armor, it’s always in the past tense.  A WWII battleship can’t stop a cruise missile.  A modern ship can’t carry the weight of WWII armor - proven false in a previous post but it illustrates how we reference armor.  Armor, even WWII armor, can’t stop torpedoes. 

Why don’t we discuss armor in the future tense.  Why don’t we say, this next frigate will have armor that … ?  It’s because there have been no advances and, therefore, we have no expectation of any advances.  We all read the news and we know that no one is even working on armor development. 

Why is that?  Why is no one working on armor development?  Is there something inherent to armor that makes it immune to scientific advancement?

Land vehicle armor has made advances.  Not as much as aircraft, weapons, and sensors but still significant advances.  Chobham ceramic armor lead the way.  We now have layered armor, composite armor, V-shaped armor, perforated armor, spall liners, reactive armor, and probably a bunch of other armors that I don’t know about because I’m not a land warfare expert or because they’re classified.  Why has no one tried to adapt any of these armor technologies to ships?  Why has no one made any effort to develop new naval armor?

Sure, some of these armor technologies may not be suitable for ships but have you even heard of a failed attempt to adapt land armor to ships?  The only adaptation of land armor that I’m aware of is Kevlar linings for use as anti-splinter protection so this can only marginally be considered armor and certainly not in the sense that we’re talking about here.  I am an expert on naval matters and I keep a close eye on naval technology and I can’t recall a single report of any naval armor research, successful or not, in modern times.

Why has the Navy totally abandoned armor research?  And why have we, the observers and commenters, accepted it?  None of us question why a Burke, the most advanced and powerful surface ship on the planet, costing over $2B, has almost no armor and thinner, weaker hull plating than a WWII Fletcher? 

Something is seriously wrong with this picture!


  1. Good question I have read where all WWII battleships had armor that required resistance at least to that of its main guns why then have ships not been tested to resist at least a 500 lb warhead of a Harpoon at the very least.

    1. Not for the full armour, that only applied for the very heavy armour strip along the water line. The top armoured deck- which was inside the hull not the weather deck were only designed to limit the damage from a plunging shell, not resist it. Any way the bombs carried by planes soon had far more explosive power then an AP shell and very heavy armour was seen as not protection for the most relevant threats. Same goes for torpedoes, far more explosive power than a shell against the hull, so the method was , and still is, to expect a big hole but limit the damage in critical areas.
      Its the whole system of damage control, which starts with maintaining stability even when some compartments are filled with water, damage resistant bulkheads, redundancy of essential features and so on.

    2. Most of your assertions are incorrect. Do some research on post-WWII armor/shell penetration. There is some fascinating experimental work posted on the Internet.

      I don't know why navies abandoned armor but it's not for the reasons you put forth.

    3. The claim was .."WWII battleships had armor that required resistance at least to that of its main guns"
      Iowa class, belt- the waterline armour- 12.1 in. the decks : main 1.5 in, 2nd or armoured deck 6 in
      The belt was expected to resist the 16 in, while the deck armour could not ( 6 in was the belt armour of a late war Des Moines). The arrangement of two decks with 1.5 in and then 6 in contains a plunging shell not resist its penetration

      From memory there were very few hits on belt armour by a comparable ship in WW2. Of course now days guns are mostly for shore support , not firing at other ships, unless they are much smaller in size.

      Thats not to say modern hulls cant have thicker and HY steel, which is sometimes used for structural reasons , not protection.

    4. Read Nathan Okun's work before you comment again.

  2. Modern "armour" is early threat detection, defensive gatlings/short range missiles and countermeasures. Modern day threats cannot be countered by armour designs without the warship being huge (read : heavy) hideously expensive and slow.

    1. This is an absolutely incorrect comment. I've repeatedly demonstrated in posts and comments that none of your assertions are true. Read through the archives before you comment again.

  3. A couple weeks Cmdr Salamander asked a former head of the Ford program what emerging technologies he thought would impact naval warfare. The former head of the Ford program stated that there was a classified technology that can defeat shaped charges that exists and that he tried to get put on the Ford. However, the armor was cut. He also said that this technology should become part of the fleet, and that armor is more important given the spread of cruise missiles.

    1. Fascinating. I missed that. Do you have a link or reference?

    2. Anonymous might be referencing electric reactive armor.

      Wiki discusses two types, which at first blush, I think would have limited applicability on an aircraft carrier. It's one thing to shield against an RPG or an ATGM, but quite another to shield against an ASCM going at Mach 3.

    3. Starts in minute 59

    4. I suspect that Manvel was referring to dynamic armor

  4. I think part of it went back to the early Cold War years, the idea of nuclear battlefields, or nuclear war at sea in this case. Where missiles trumped guns, as seen in some USN cruisers and aircraft like the early F-4s. The idea of armour plate to resist a nearby nuclear detonation seemed like a waste of displacement. As were medium calibre naval guns. It also can account for why USN ships had sparse CIWS coverage, usually no more than 2 mounts, where the average Soviet DD/CG had at least 4 on average.

    At some point they stopped being built to take a beating and keep on fighting.

    Some of these ideas were later reversed. Medium calibre guns were restored to those gunless ships. The F-4 eventually got a gun. People realised that war could be something other than 'nuclear or nothing'.

    But as you say, armour never came back into vogue. A little kevlar splinter protection doesn't count - as witnessed by the extensive damage from those BQM-74 fragments against the Tico CG. And USN CIWS are still minimal, in general. Strange, since there were engagements from which lessons could be drawn. The Stark. The Sammy B. Tripoli. Princeton.

    We see the same mentality in the LCS even now, where they don't even expect her to take a single hit and keep fighting (or limp home) but rather to allow an orderly abandonment.

    Given all the compromises that go into a new USN ship design, it is hard to imagine that new armour technology will receive high priority even now.

    Which is a real shame, as we sail about in these fragile warships that rebels in a dhow can rake with machine gun fire and achieve a mission-kill, at least temporarily.

    1. Yes, the ability to withstand a heavy machine gun is minimal, and remember these countries have the ex Soviet 14.5mm heavy machine gun , which packs twice as much punch as a 12.7mm

    2. "I think part of it went back to the early Cold War years, the idea of nuclear battlefields"

      I've heard this claim many times and I have never found a single shred of evidence to back it up. I'm thinking this is another of those popular myths like the torpedo breaking a ship's back by suspending it over a bubble. Do you have any evidence whatsoever to support this claim? It could be true but I've never found any evidence and, frankly, it seems idiotic but many Navy decisions are so who knows?

  5. At risk of exposing myself to the realms requiring citations to be acceptable, I am going to go ahead and stick my neck out here and respond to something.
    "Why has no one made any effort to develop new naval armor?"
    We have.

    I'm not at liberty to say a lot here (non-disclosure agreements), but between WW2 and now there have been several materials developed that qualify as armor-grade (excepting the obvious HY series), such as 'Hi-Blast NiCar'. It and all similar developments were merely sidelined as 'too expensive' to use in mass; a decision of which I have always protested as beyond insane (they are willing to spend billions on luxuries like female at-sea habitability, but $120 million is too much to armor the ship?!).
    In a more recent development, I have heard that Dahlgren has recently (2 or so years) developed 'Nano Carbon Epoxate Hyperwoven Laminate' (or 'Carbon Nano Plate' for short), which is practically invulnerable to all known weapons systems - between 26 and 64 times as durable as steel at only a fragment of the weight, and practically immune to thermal effects (well enough to survive a nuclear blast, not that this would help the crew), on top of being inherently nearly invisible to radar (I can explain this if you want, it is just outside the scope of this comment).
    Unfortunately, it's also well over a thousand times more expensive than steel plating of comparable thicknesses.
    Of course, even if the rumors I had been hearing were unfounded, the physics behind the claimed material work out and the materials/industry required are all existent in present day. I won't bore you all with the technical and industrial aspects of it, merely to say that the (former) engineer aspirant in me had to check everything already.

    Therefore, I must say:
    "Why has the Navy totally abandoned armor research?"
    Technically speaking, they haven't, we actually have spent a good deal of capital on developing new materials. They just refused to introduce it or require armor in the fleet, and covered everything up in order to not make themselves look bad to the casual observer. A near complete waste, in my opinion, if they never intended to use the material in the first place.
    I could wax and wane on the potential reasons until the cattle come home, but I'll simply apply Occam's Razor and reduce to the most probable hypothesis: they don't want to rock the boat and risk their funding. Not that this makes much sense to someone looking at it from the outside, applying armor to their vessels would only increase the navy's funding as a whole, but attempting to view the situation from inside the (carrier centric) bubble they have created for themselves lends to this assumption as to the source of their lunacy. However, I am someone who advocates the return of the heavily armored Super-Capital type Battleships, so I am biased in this regard.

    Long story short, I'm in agreement with you, something is seriously wrong here.

    - Ray D.

    1. I'll accept your comment at face value with two caveats:

      1. I absolutely believe that you believe what you said. That doesn't necessarily mean it's correct, however.

      2. All serious research, even failed attempts, gets written up in reports, patents, funding proposals, etc. The fact that I've never seen anything about any of these technologies suggests that they may not have been anything more than rumors or concepts, as opposed to serious developmental research.

      Objectively, the claims for these armors border on unbelievable and sound more like the story that some scientist invented a car engine that runs on water and the oil companies squelched it. You can appreciate the borderline incredulous nature of these claims, right?

      So, I have no reason to doubt you but there is nothing publicly available, that I'm aware of, to support you, either. As I said, I'll accept your comment at face value and continue to look for supporting evidence.

      I appreciate the comment and hope it's true!

    2. "...They just refused to introduce it or require armor in the fleet, and covered everything up in order to not make themselves look bad to the casual observer."

      I think Ray D. makes a good point there at the end and gets closer? to the truth and Ill try to expand on it: naval armor hasn't been used since pretty much USN and all other navies have gotten rid of battleships and heavy cruisers types that had big guns, wouldn't it look "weird" that after 50 years of NOT requiring armor, USN came to Congress and said:"we need armor NOW!" I think the first question would be:" why now?" and second question should be:"why didn't you need armor in the past?" What would be USN justification? Just about any answer would probably reveal that USN sent ships to battle with little protection, if ASM went past layers of missiles and CIWS, that was that! Makes them look bad and have to explain their past reasons and future reasons why they need it now. Not sure USN could give Congress the right answer....

      Other thing too, for some reason, as CNO states, why did we really get rid of armor? You can go on other blogs and talk land armor ALL DAY but for some reason, naval armor is ancient history, would be like saying USN should go back to using sails or US Army should get rid of tanks and uses horses again!

    3. "You can appreciate the borderline incredulous nature of these claims, right?"

      Oh, absolutely, CNO.
      Upon initial hearing of the rumors, of 'Carbon Nano Plate', I was beyond incredulous and refused to believe it until I had dug deeper into the materials supposedly involved.
      This is why I immediately deflected to the assumption that the rumors were unfounded and attempted to reconstruct the concept on the basis that it wasn't real, I ended up finding out that the material is in-fact at the very least plausible.
      In essence, 'Carbon Nano Plate' was proposed as hundreds of sheets of Carbon-Nanotubes (CNT) laminated together with a bonding epoxy at high heat; given CNT's material strength some 600-1000 times higher than steel, a claimed loss of 93.6 to 95.6% material strength automatically made the rumor a little more believable (if you are going to spread rumors of a ludicrous wonder material, you may as well go for broke); as for the other claimed properties, these are ironically actually known properties of Carbon-Nanotubes themselves: randomized patterns of CNT act as a form of Radar Absorbent Material and are extremely resistant to thermal effects given the material's heat dissipation qualities; in addition, CNT on the molecular level simply does not want to be disarranged, and actually displays characteristics similar to self-sealing materials as the molecules snap back together.
      Given that the materials science behind the plating was valid, I then began questioning the production side of the equation - CNTs are notorious for their inability to be produced in mass, especially not in sheet form like this would require.
      Lo and behold I would find out that there is a US firm that cracked how to make it happen, and there IS research into the material. Specifically, the material in question here is 'Miralon' (produced by the firm NanoComp Technologies), and it is currently in use by NASA and is being considered for use in aircraft. Unfortunately, there is limited public information available on the material beyond this aside from some NIJ certification and its materials certification by NASA, but information on the capabilities of CNT itself is public access and has been the gem in the eye of materials researchers for about 30 years now. It was merely considered impossible to produce in sufficient masses to be able to be used in practical applications... until 2012, when mass-production tests proved not only plausible, but reasonable (albeit on a low scale).
      In the end, what I determined was that the groundwork is there, but the materials are too expensive to allow for large scale testing and further research into capital ship type armor plating. Not a confirmed rumor, but I had to admit that scientifically it was in-fact eerily plausible.
      Just thought I would give a (very) little insight into the trail I followed to come to my conclusion, something to look into a little bit if you want to pursue it. Materials such as Miralon do have a paper trail to look into, after all.

      - Ray D.

    4. Absolutely fascinating! Keep me informed if you hear of any developments.

    5. I submit that there are at least two reasons why ship armor has been shoved to the rear of the bus. First - It's not sexy like a new electronics box designed to ward off all incoming missiles or a Mach infinity missile. Second - Navy decision makers have never taken incoming rounds while aboard ship, and THAT will make you take a whole new look at the problem of survivability and lifeboat training.

    6. Your second reason is especially perceptive and, no doubt, has more than a large element of truth. Good comment.

    7. Regarding my last observation - about 30 years ago I was the precom navigator of a Spru can and took all of my duties seriously, including the need to provide navigation services to the collection of ship's lifeboats should we ever be forced to abandon ship. We were at NTC San Diego at the time, so my suggestion for a surface ship lifeboat survival course paralleling the aviators' course went up that chain of command. All the way up to ComNavTraCom and back down, the course was deemed unnecessary. Apparently, U.S. Navy ships no longer sink. Problem solved.

    8. Alan Gideon. Greta comment and I think you hit it on the nail. USN ships don't face combat and sink!

      Wonder how much that attitude is prevalent at the top?

    9. @ Ray D. and ComNavOps:

      Small world, but I actually lived just down the street from NanoComp when they still had a facility in Concord, NH.

      The problem with any fiber-reinforced composite is the high degree of anisotropy, not only in tension and compression, but sheer as well. In general, the sheer strength of fiber-reinforced epoxies/polymers isn’t usually that much better than the sheer strength of the epoxy or polymer. Consequently, I’m quite dubious about “carbon nano plate” being the wonder armor claimed, in and of itself. It would probably need to be used in conjunction with a good strike-face material.

      With respect to impacts that are perpendicular to the plane of the fibers, the performance of a fiber-reinforced composite will tend to increase as sheer stress decreases. In other words, you want to spread out the force of the impact as much as possible before the projectile encounters the fibers. This is the principle behind ceramic armor composites. The hard, but brittle, ceramic strike plate shatters and/or erodes the projectile so that the forces experienced by the backing materials are spread over pieces of the projectile and spawl, thus reducing sheer stress and allowing the fibers to convert the sheer stress into tensile stress, which they are extremely good at resisting (i.e., the backing material “catches” the remaining fragments).

      Another issue is the degree to which the composite is designed such that the fibers adhere to the matrix. In carbon fiber epoxy composites and the CNT composites that I’m aware of, the fibers strongly adhere to the matrix. As a result, the mechanical properties of the material are almost entirely dependent on the properties of the fibers. These materials tend to be relatively brittle, at least in terms of their failure mechanisms (i.e., they can still be extremely tough due to the extremely high modulus of the fibers and relatively high failure strain, but they tend to shatter when they do fail). In an armor application, this can be an issue because it will generate additional fragments that something else will have to resist. This is not the case, however, in all fiber-reinforced composites.

      The fibers in many metal and ceramic matrix composites are actually treated (often a high confidential trade secret) so that the fibers do NOT adhere to the matrix, and thus, the matrix and fiber can move relative to one another. In these composites, the fibers increase the toughness of the matrix via fiber pull-out during crack propagation. Ceramic matrix, fiber-reinforced composites are very attractive materials that are currently receiving a lot of attention by the likes of GE, to name just one example.

      If I had to put my money on the one new armor system that we are most likely to see applied to large structures (i.e., not just bodyarmor), it’s going to be a SiC/SiC or SiC/C ceramic matrix composite strikeface over a UHMWPE backing plate, or possibly a similar combination of materials in a nacre-inspired, brick-and-mortar arrangement, because they are already fairly well understood and the stock materials are relatively inexpensive.

      - Gripen

    10. But don’t count metals out either. I, for one, think that we should explore using titanium alloys to armor critical components of ships. While commercial grade titanium alloys are WEAKER in absolute terms than many commercial high-strength steel alloys, they could make for good interior bulkhead armor around critical ship infrastructure because they tend to fail by yielding rather than shattering (as in high carbon steel alloys) and thus will not generate as many secondary fragments as steel bulkheads. They could be backed up even further with kevlar, UHMWPE, or other advanced polymers/fibers.

      Functionally graded, additively manufactured and/or powder-metallurgy armor plates offer a lot of promise utilizing blends of existing alloys (and ceramics) in novel geometries. Using these techniques, it’s possible to create a homogenous armor plate with a hard strike face and ductile backing with much more design freedom than traditional deferentially-hardened plates (e.g., krupp cemented steel).

      “High entropy” metal alloys are also an intriguing area of research, but the highest performing ones all seem to require significant amounts of insanely expensive alloying elements, such as scandium. The hope is that such phases can be replaced by another metal, intermetallic, or ceramic phase.

      Using finite element analysis (FEA) techniques and some super-computer time, it should also be possible to optimize armor selection and placement (even using current materials) to provide the same or better protection than previous armor schemes at reduced weight. I’d be particularly interested to see what we could come up with using FEA as far as torpedo/mine protection systems using polymers and/or ductile alloys in hierarchically-ordered, controlled-deformation crush structures.

      - Gripen

    11. *Shear stress.

      It's been a while since I've done any of this sort of work on a regular basis, although I still try to follow developments as much as I can.

  6. Just saw this from 2006? when somebody asked the same question on another blog. I don't know about this guy and his book but he seems to know something about naval construction.

    "You're all wrong. It was a topside weight saving measure.

    In WW II and the Korean War American warships were designed to withstand certain types of weaponry even ABOVE the main deck. I worked on a Destroyer that had plug welds in the superstructure where the skipper literally beached the ship to provide close-in fire support. Commie troops peppered the ship with rifle and machine-gun fire.

    But didn't do one iota of damage except giving the DC gang a chance to improve on their welding techniques.

    Then came the contract manufacturers of "better" antennas, "better" receivers an "better" black boxes that insisted that for the system to work the main receiver could be no more than a 50 foot run of waveguide or coax to work properly. Otherwise the warranty was void.

    So all the heavy, unmovable electronics equipment was moved above the main deck (in some cases WELL above the main deck). Crew quarters and galleys were moved down below. Originally, critical equipment was below main deck to use the value of thick shell plating and extra bulkheads to at least protect it from shrapnel.

    Now, topside weight is so critical the superstructures on all ships is aluminum which is 1/3 the weight of steel but also 1/3 the strength. We could not afford (weight wise) to armor anything above the main deck. Only some Spruance class Destroyers were able to take some added "Fragmentation Protection" of extra thick aluminum in specific places (read my chapter on Armor in my book).

    Additional black boxes and gee whiz gizmos brought the Perry Class Frigate up from 2700 tons to 3100 tons. We had to take over an entire fuel tank and fill it full of lead ingots. Additional reinforcement of the hull was needed and the waste drains raised a full foot so they would dump poo poo above water.

    Only the Battleships were big enough, broad enough, ballast compensable enough to add more armor topside. Even then it was called "Fragmentation Protection" to stop shrapnel from a near miss.

    Even for terrorists zipping along in a speed boat with a 12.7mm machinegun required me to design an armored dolly for the AVGAS fuel bladder for the RPV planes on the BB's.

    I was tasked to design armor for the ammo magazines of the Tarawa Class LHA's and the Spruance Class DD's. Being an ex tank crewman that loved the Mah Deuce .50 MG, I always tried to sneak in thick enough design to stop ball ammo from that kind of gun.

    But it can't be done easily, not without violating contractural agreements with the suppliers of the electrontonic doo-hickeys.

    See my chapter on "How do I get out of this C**S**t outfit?"

    1. NICO, if you quote a person or blog post/comment, please credit the source with a link or reference. I'd want that if someone quoted something of mine. Also, it's interesting and I'd like to look into this a bit deeper. Thanks.

  7. Sorry about that, was in a hurry to get to work. I'll see if I can find the source and post it correctly. My bad.

    1. If you could also find out what book he was referring to, that would be great. Thanks.


  8. OK, this time I hope I do it right. The forum is called:
    " World Affairs Board": you can ask an expert for naval questions.

    The thread was: "Thread: why the elimination of armor in modern naval ships?" and it started in 2009. Haven't seen any recent additions to that thread.

    The gentleman that gave the most interesting answer was RustyBattleship. He is gravely ill and only has a few months left to live. He has a book due in the next few days on Amazon. I haven't found the title yet, have sent a request.

    I just signed up so I have no clue yet about the quality of the threads and how the debates go but so far, looks decent enough. Im so tired of the pissing matches and flame wars.

    1. "RustyBattleship"

      Dick Landgraff. It has been a while since I heard that man's name, it's a mighty shame to hear about his illness, however. But I digress.
      It doesn't really matter, but I can vouch for the man's expertise.
      He is one of those individuals whose raw experience in shipbuilding alone speaks enough volumes that full Engineers will toss out the book and defer to him when it comes to his field of expertise.
      He is effectively America's (and the world's) last living expert on the construction and maintenance of Battleships and Super-Capital ships, we will lose generations of hard earned knowledge and experience when he passes. I only hope we are capable of learning it all over again on the fly when we need it, although I am not optimistic on that front.

      - Ray D.

  9. MM-13B, found the book, it's on Amazon and you can download it. Looks interesting, the guy sounds like a living walking naval encyclopedia...

    Revision "B" of my first edition: A History of LBNSY, Roosevelt Base & Reeves Field N.A.S. Rev "B" Paperback – June 24, 2017

  10. Couple of thoughts:

    Was reading an article on FB, can't find it now! on the second Chinese aircraft carrier and it's starting pier trials. Small tidbit of info was the remark that the team involved on Chinese carrier had average age of 36! Not sure if true and what the break down of ages and qualifications are but it sure seemed young. Made me wonder about the current topic of armor and sadly how the gentleman naval expert was sick and like most of his generation will be passing away. How old is our industrial base? Not just the machinery but the workers? Not saying we need to build a BB but could we still build one? Do we make enough HY steel to make one? The knowledge? Do we have enough welders? Do we train enough people to go into these fields of military production? I saw a picture years ago of the Boeing team that designed and built the prototype Bird of Prey. Average age was supposedly 55. How long can we continue like this?

    Seems to me we are in a similar situation when USA after WWII had a bunch of young, experienced engineers, aided by German research and took it to a WHOLE new level in the 50s, 60s, even 70s BUT this time, it's the CHINESE that are young and gaining experience, some espionage help and they are the ones that will explode with new ideas.

    1. You're addressing institutional knowledge and, yes, it's an incredibly important factor and one that is being lost every day.

      Excellent comment.

  11. Incredible how far we've come isn't it? If we go back to let's say, 1903 at the time the wright brothers flew, most people would laugh at the idea of an aircraft carrier. Fast forward decades later and such a "preposterous" idea is now the navy's most important asset alongside the submarine.

  12. At the very least, double hulls should be required. This not only gives reserve buoyancy, and some protection against torpedoes, but can also act as spaced armor to help protect against some smaller shaped charge weapons including those pesky swarm boats. A peripheral VLS similar to the Zumwalt could use the top of the outer hull, but should be tactical length (ESSM only) so as not to add too much weight. It would also help against missiles like Brahmos which have an enormous amount of momentum due to speed and weight--a "destroyed" missile could still rain high speed debris that can damage a hull if intercepted a close (say CIWS) range. WW2 Kamikazes in 300mph wooden planes might get hit dozens of times and be on fire when they plunged into a ship--now make that kamikaze do mach 3.

    Armored belts can be retrofitted to existing hulls. With ceramic/composite armor. Not even the mighty Abrams has just the same armor it started with: they add on new armor to the old when things like depleted uranium armor are developed. Even a quick look at the Wikipedia page on vehicle armor gives a nice primer of where to start

    Oh, we also armored boats in Vietnam. The Riverine force monitors-modified landing craft-had armor added. Around 10 tons according to Wikipedia. One type of of armor was bar armor for protection against RPG's. You see the same bar armor today in Iraq and Afghanistan on some land vehicles.
    Some good pictures and info on the Vietnam era program 4 monitors at