Forged By The Sea

Forged By The Sea.

The new Navy slogan. 

Pure marketing bilgewater. 

Yes, it’s probably better than “A Global Force For Good”, which sounded like the Peace Corps, but it’s still worthless.  Why is it worthless?  Because it doesn’t reflect any core value of the Navy.

The Marines used to have this right with their “The Few, The Proud, The Marines”.  That reflected their core belief, and actuality, that they were an elite fighting organization and that ethos not only supplied the slogan but it transcended petty concerns like marketing.  Marketing???  That’s hilarious.  The Marines not only didn’t care whether they appealed to a mass market of recruits, they actively discouraged potential recruits and stated that they didn’t think any potential recruit was good enough or tough enough to be a Marine.  As is true with human nature, the Marine’s very exclusivity and disdain for the average potential recruit ensured that they would attract the best and toughest potential recruits – those who relished a challenge and were determined to prove themselves worthy of being one of the very best.

Of course, sadly, the Marines have now abandoned their core.

The Navy’s new slogan is just a marketing jingle.  It has no underlying meaning or value.  It doesn’t relate to any core Navy value because, frankly, the Navy has no worthwhile core values at this time.  Fat Leonard, surrendering to Iranians, ceding the South China Sea without contest, whining to Congress, lying about the LCS, waiving required basic seamanship certifications – these are the “values” that the Navy espouses now.

It doesn’t matter how brilliant or relatable or catchy or memorable or inspiring the Navy’s new slogan is because it has no meaning.

Ironically, "forged" also means to copy fraudulently or to fake.  Apropos, wouldn't you say?. 

The Navy hired a marketing firm to develop this slogan and paid a great deal of money for someone to write a slogan for them.  Hey Navy, establish some core values and the slogan will write itself.  Live some core values and you won't have to recruit, the recruits will come to you begging to be allowed in.

Henderson Field

A recent article about the Marines, sea control, and HIMARS cited Henderson Field (Guadalcanal – WWII Solomons campaign) as an example of an expeditionary base.  This is an interesting case that warrants a bit of examination.

Many military observers and, apparently, many professional military thinkers seem to have a vision of austere, hidden jungle bases from which a handful of F-35B’s wreak havoc on the surrounding enemy, immune from discovery.  I swear, most people seem to have this image:  the chirping and chatter of jungle life will momentarily pause, the jungle canopy will rustle, the branches will part, and an F-35B, dripping with all manner of weaponry, will rise, vertically, out of the jungle, undetected, and fly off to decimate enemy forces and return to repeat the cycle until the enemy is brought to their knees.

The Marines are not immune to the lure of this vision. 

“The Marines would provide additional “distributed” firepower from Expeditionary Advance Bases. Carved out of hostile territory by landing forces, kept small and camouflaged to avoid enemy fire, EABs would support F-35B jump jets, V-22 tiltrotors, and drones, as well as anti-ship missiles for the fleet. It’s a high-tech version of Henderson Field on Guadalcanal (part of the Solomons) in 1942. Like Henderson Field, the EABs would provide a permanent presence ashore, inside the contested zone, to support Navy ships as they move in and out to raid and withdraw.” [emphasis added] (1)

Let’s look at the historical example of Henderson Field and see what we can learn from it that can be applied to today’s Marine Corps Expeditionary Advance Base concept.

-The most obvious characteristic of Henderson Field was that it wasn’t hidden or unknown to the enemy.  The Japanese knew exactly what it was and where it was!  The assumption that any airbase large enough to operate multiple modern aircraft, sensors, warehouses, fuel depots, munition dumps, etc. will remain hidden is pure fantasy.

-Henderson Field was bombarded on an almost nightly (and daily!) basis by both aircraft and ships.  Because the Navy didn’t control the sea, the Japanese were able to bombard the field almost at will.  The Marine’s concept of a base located in enemy controlled sea (or, at best, no man’s sea) that will be somehow immune from attack is delusional.  Worse, unlike WWII where the bombarding forces had to come near the field and were subject to counterattack, today’s enemy can simply launch ballistic and cruise missiles without ever exposing their own forces to direct counterattack.

-The regular bombardments, combined with the primitive conditions and lack of spare parts and skilled maintainers, meant that the field usually only had a handful of operational fighters at any given moment.  How much worse would this be with modern, finicky stealth aircraft that require advanced technology for diagnostics and maintenance and require pristine conditions to perform maintenance and maintain the stealth characteristics of the aircraft?  The very nature of a forward area, austere base guarantees that readiness rates will plummet.  Considering the F-35 is struggling to achieve 50% readiness under ideal conditions with highly trained factory service personnel and ample spare parts, it’s a certainty that aircraft readiness will be abysmal.

-Henderson Field was a very large base!  Now, the jump jet supporter’s response is that we’ll operate vertical landing and takeoff F-35B’s so we’ll only need ten feet of runway!  Of course, that’s incorrect.  With any useful weapon and fuel load, the F-35B won’t be taking off vertically.  It needs a runway.  It may not need a 10,000 ft runway but it will need a significant one in terms of visibility to the enemy.  Of course, there’s also the parking areas for each aircraft (you don’t park a modern aircraft in the mud, under a tree), hangars to perform clean maintenance in, computer facilities for diagnostics and mission planning, munition dumps, spare part warehouses, fuel storage tanks, barracks for all the pilots, maintenance personnel, and command staff, radars, control towers, aircraft support vehicle storage/parking, food facilities, and sanitary facilities.  On top of all that, an expeditionary base is, by definition, in enemy territory so there will have to be a defending force with vehicles, anti-aircraft vehicles/sites, radar, more housing, food, and sanitary facilities, etc.  How all of this is “kept small and camouflaged to avoid enemy fire” is a mystery that the Marines have yet to explain.

-Let’s also recall that because Henderson Field was in enemy controlled air/water space, we had difficulty resupplying it, especially early on.  Resupply and reinforcement was sporadic, at best.  A modern aircraft and expeditionary base needs immense amounts of fuel, munitions, computers, electronics, spare parts, etc.  Keeping a modern expeditionary base supplied would be even more challenging than in WWII.

-Trying to operate an expeditionary base in enemy air/water space is going to be costly.  Recall that we lost many cruisers, destroyers, and one carrier (Wasp) trying to defend Guadalcanal.  In WWII, ship losses were relatively quickly and easily replaced.  Today, with only a couple of shipyards in the U.S., we’ll be hard pressed to replace our losses and to believe that we’ll be able to “carve” out a base, equip it, operate it, and resupply it without being noticed and without suffering significant losses is pure fantasy.  Does it really make sense to lose dozens of ships to defend an expeditionary base?  It might, if it’s strategically beneficial.  The point is that any base large enough to be operationally beneficial will be noticed and we will have to fight to defend it and the heavy losses must be factored in rather than just blithely stating that we’ll “camouflage” the base and the enemy won’t see us.

-Recall that we lost many aircraft at Henderson Field to combat, bombardment, and poor ground conditions.  For example, from Wiki,

“Between 21 August and 11 September, the Japanese raided Guadalcanal a total of ten times, losing 31 aircraft destroyed and seven more heavily damaged, primarily due to the defensive efforts of CAF fighter planes. …  During this same time, the CAF Marine Corps fighter squadrons lost 27 aircraft with nine pilots killed.”

Again, in WWII, aircraft were very easy to replace.  Today, F-35’s and MV-22’s can’t be as readily replaced.  Will the losses be worth it?  Again, perhaps but we need to acknowledge and factor in the enormous losses as we discuss these things rather than just hand-waving away the problems.

-Henderson Field was a very primitive base.  Huts, mud, rain, dust, dirt, insects, humidity and accompanying rust and corrosion, and disease were the hallmarks of the base.  An expeditionary base “carved” out of enemy territory won’t be any better.  Those conditions took their toll on pilots, maintainers, and aircraft alike.  How will modern, exquisite, stealth aircraft stand up to such conditions?  Not well!  The F-35 has only a 50% readiness rate now, at fully equipped, pristine bases with ample supplies of spare parts, manufacturer tech reps, and maintenance personnel.  What do you think it will be when mud, rain, dirt, and rust start working their magic?  Sure, we could pave the runways, taxiways, and parking.  We could build insulated buildings with climate controlled atmospheres to house the computers.  We could build filtered air hangars with moisture control to work on the aircraft.  We could set up advanced hospitals with extensive medical staffs to keep the pilots and maintainers healthy.  We could do all that but then it’s not an expeditionary base, is it?  And it certainly won’t be hidden with all that!

F-35 Operating Base?

Henderson Field is an example of a forward base but it certainly isn’t an example of a secret expeditionary base, small and camouflaged and hidden from the enemy. 

There’s nothing wrong with the idea of a forward base, if the strategy requires it, but let’s be realistic about what that means.  It means a base that will be well known to the enemy, a base under constant attack, a base that will struggle to achieve aircraft readiness rates of 25%, a base that will consume unbelievable quantities of supplies, a base that will require the efforts of the entire Navy to defend and supply, and a base that will cost us almost as much as we gain from it.

Let’s drop this fantasy of hidden bases once and for all.

______________________________________

(1)Breaking Defense website, “Marines Seek Anti-Ship HIMARS: High Cost, Hard Mission”, Sydney J. Freedberg Jr., 14-Nov-2017,

https://breakingdefense.com/2017/11/marines-seek-anti-ship-himars-high-cost-hard-mission/

Supertanker Frigate

An issue of Proceedings has a short article by Dr. William Stearman in which he proposes a new Navy warship based on a super tanker with a 250,000 long-ton, full load displacement, 1075 ft in length, 170 ft beam, and 80 ft draft (1).  Stearman’s proposed vessel is, in turn, based on a comment he quotes from Kenneth S. Brower, as follows.

“Very large supertanker hulls, that are well designed, approach being unsinkable.  I would bury a FFG/DDG combat system somewhere inside these vital hidden areas with advanced armor and would trade speed for survivability and reduced cost …”

The article goes on to describe some of the benefits of such a large ship

• Greatly reduced vulnerability to under keel torpedo or mine explosions due to reduced likelihood of hull girder failure

• Side structure with alternating layers of water and steel bulkheads would likely defeat even shaped charge missile warheads

The author then proceeds to describe a do-everything version of this ship which includes almost everything that has ever been installed or proposed for a naval vessel: a flight deck for MV-22, F-35B, helos, etc., 5” guns, 8”-12”+ guns, VLS, amphibious craft, and a Marine Expeditionary Unit (MEU) – all in one ship!

Let’s set the do-everything ship aside as fantasy and instead contemplate the much simpler concept of a frigate/destroyer based on a very large commercial hull.  There is, actually, something to be said for such a ship.

The immensely large hull, if built to commercial standards and patterned after a tanker, would, indeed, be very, very difficult to sink.  The example of the mining of the SS Bridgeton in 1987 and the almost complete lack of relevant impact and damage from the explosion attest to the inherent resilience of large tankers. 

The idea of embedding the actual combat elements deep inside the ship’s internals and protected by additional localized armor, offer the possibility of a ship that could absorb immense amounts of damage and still continue to operate.

Frigate?

The flaw in this is that the sensors and actual weapons would have to be exposed and would be as susceptible to destruction and subsequent mission kill as any other ship.

In addition, the sheer size and non-stealthy nature of the ship would make it the equivalent of a beacon, proclaiming its location.  An enemy would have no trouble finding this ship – sinking it, however, would be a challenge. 

Taking the discussion a bit further, even if we didn’t want to actually build a tanker-frigate, we might want to consider modifying warship designs to incorporate some scaled down aspects of the design of a commercial supertanker such as the alternating water/bulkhead sides, increased beam and draft, etc., if those modifications can gain us significant survivability.

I’m not necessarily advocating this approach – a naval architect/engineer would have to evaluate the concept – but it’s interesting and worth a few moments of thought especially given the flimsy nature of today’s warships.

____________________________________

(1)Naval Institute Proceedings, “Revolutionary New Ship For The Navy?”, Dr. William Stearman, Aug 2017, p. 87

Supercavitating Torpdeo Kinetic Energy

Recently, there have been a few comments asking about the kinetic energy of a supercavitating torpedo with the suggestion being that the kinetic energy, alone, makes the torpedo a one-hit killing weapon against any size ship – essentially vaporizing the target.  Well, kinetic energy is  easily estimated. Here's the calculation for the Russian Shkval supercavitating torpedo.

k.e. = 0.5 * m * v²

m = mass = 2700 kg; Russian Shkval torp

v = velocity = 100 m/s; 200 kts

so,

k.e. = 0.5 * 2700 kg * (100 m/s)*(100 m/s)
k.e. = 13,500,000 (kg*m²)/s² = 13,500,000 J

By comparison, a kg of TNT releases 4,184,000 J. Thus, the k.e. of the supercavitating torpedo is equivalent to around 3 kg of TNT. To put that into context, a U.S. Navy lightweight Mk54 torpedo has a warhead weight of 44 kg (we'll assume it's TNT even though it isn't). That means the supercavitating torp would have kinetic energy equal to 7% of the explosive energy of a Mk54 lightweight torpedo - not enough to even be noticed, by comparison and certainly not a one-shot kill/vaporize due to kinetic energy alone.

Torpedo and Mine Damage History - Part 2

In Part 1, we examined some of the historical examples of the effects of underwater explosions from mines and torpedoes on ships.  We found, as we did with our scholarly examination, that the myth about torpedoes breaking the back of ships is just that – a myth, at least for ships the size of large destroyers and above.  Further, we found that even significant structural damage – significant in the sense of threatening to sink the vessel – was rare to non-existent.  The next obvious question is, why?  Where does this torpedo damage resistance come from?  What is it about the structure of a ship that provides such resistance?

The answer is both obvious and largely unknown and unrealized, at least outside naval architect circles and possibly even within.  The answer is keels.  Note that the answer is in the plural – keels.  Few people realize that ships have multiple “keels”.  Now note the enclosure of the word in quotes, indicating that the word is not to be used literally.  Huh?  What are we talking about?

Ships have multiple “keels” (I’ll now stop putting the word in quotes, for ease of typing), most of which are unintended as such but are nevertheless present.

Consider …  A keel, without getting too technical, is the bottommost, main structural longitudinal member of the ship.  It runs the length of the ship and provides the backbone upon which all the other structural elements attach, either directly or indirectly.  For this reason, the torpedo bubble crowd believed that if the keel (the ship’s “back”, like the spine of a human) were broken the ship would automatically sink.

What few people realize is that there are other longitudinal structural members in a ship that act as keels. 

Armor belts on the side of a ship are complete, solid structures that run a significant length of the ship and are intimately attached to the ship’s structure.  Thus, they constitute two additional keels.

Armored (or even simply thick) decks also run the length of the ship and act as longitudinal structural members or keels.  There can be one or more, depending on the number of armored decks the ship has.

Some ships have longitudinal bulkheads which also act as keels.

Each of these keels has the strength to hold the ship together by itself.  Thus, even in the unlikely event of the failure of one keel, the others are sufficient to protect the ship from breaking in two and sinking.

Noted naval historian Robert Lundgren discussed this phenomenon in a NavWeapons website forum topic (1).  Here are some of his comments.

“A ship with a fully developed side protective system is not subject to the type of break-up a lesser vessel is due to under-keel explosions. No capital ship ever in history ever broke in half due to an under-keel explosion even when it was a nuclear explosion.”

“In a battleship, the ship has what they call a soft keel. Any longitude bulkhead that makes up over 50% of her length becomes a strength member of the hull girder. In an Iowa as an example, her four bulkhead system on each side gives her eight additional strength members and her third bulkhead is her armor belt which is extremely difficult to place into sheer. The side protection system is so strong it can support the weight of the ship even if the flat keel is destroyed. Each layer of the side protective system acts as an additional keel so in an Iowa she has 8 side keels and her flat keel and she actually has three upper strength decks with the second deck being an armored deck which is also difficult to bend. In the roughly 2 seconds an under-keel explosion has to work on the hull the side hinges that form on lesser ships never form on a battleship or even a fleet aircraft carrier. Therefore, the upper strength deck or decks are never placed in stress. What does occur is the under-bottom is either holed or crushed in and depending on the damage will depend on the amount of flooding just like a side hit by a torpedo. The ship will whip just like Tirpitz did but not break up.”

“The 4,000 lb warheads under Tirpitz were roughly equal to 4 x MK 48 torpedoes or a 1,500 lb warhead detonating 50 feet under her keel. All underwater explosions work the same. So if a MK 48 1,500 lb warhead gives X amount of force at 50 feet this can equal a 4,000 lb warhead at 100 feet and the 28 kiloton nuclear warhead may be the same at 2000 feet and so on. So the distance and the amount of ocean on top of the explosion is important. Even Arkansas did not break up at Bikini. She basically was flipped over and landed upside down on an empty sea bed as all the water had been blown out of the lagoon.  Her hull was crushed when all that water came back down. Her sides held her together while she was in mid-air and her armor is cracked in one place near her bow but she is intact.”

There you have it.  There’s the explanation (well, one of them) for the resistance of ships to underwater explosions.  Additional resistance is also imparted by the numerous other shorter, smaller structural elements, all of which function to spread the stress load throughout the entire ship’s structure rather than having it concentrate in one spot.  The spreading or dissipation of the stress helps to prevent structural breakage at the point of impact.  We’re wandering into structural engineering, now, and that’s well beyond the scope of a simple post so we’ll leave it at that.  Suffice it to say that ships have a greater inherent resistance to underwater explosions than most people realize.

This is not to say that underhull explosions are not powerful and damaging – they are and for smaller, lighter built ships they may well prove fatal.  But, as we proved in our examination of the torpedo myth, and in our examination of historical data, they are not the instant death that the torpedo myth crowd believes. 

This concludes our examination of the torpedo myth and puts it to rest, once and for all.

___________________________

(1)NavWeaps website forum, Topic: “Threat: Torpedoes That Go Under The Keels” 31-Mar-2014, username: rlundgren,

https://www.tapatalk.com/groups/warships1discussionboards/viewtopic.php?f=64&t=25012&p=427180&hilit=%22soft+keel%22#p427180

Torpedo and Mine Damage History - Part 1

We previously examined torpedoes and their lethality and debunked the “broken back over a bubble of air” myth by examining available experimental data and applying simple logic (see, "Torpedo Lethality Myth").  However, it’s always worth looking at actual operational experience so let’s look at some historical examples of ships subjected to large underwater explosions due to mines and torpedoes and see what we can learn. 

This is the first of a two part post.  In this part, we’ll look at the historical data.  In the second part, we’ll examine an explanation for the historical data.

I’ve tried to pick a cross section of ship types, sizes, eras, and nationalities while working under the constraint of known data.  Many ships suffered mine/torpedo damage but the damage was too poorly documented to analyze.  The following examples are presented in no particular order.

Tirpitz

Tirpitz is one of the most documented and relevant examples.  According to Wiki, X-Craft midget submarines laid four 2 tonne mines on the sea bed under the bottom of the target.

“first exploded abreast of turret Caesar”

“second detonated 45 to 55 m (148 to 180 ft) off the port bow”

“A fuel oil tank was ruptured, shell plating was torn, a large indentation was formed in the bottom of the ship, and bulkheads in the double bottom buckled. Some 1,430 t (1,410 long tons) of water flooded the ship in fuel tanks and void spaces in the double bottom of the port side, which caused a list of one to two degrees, which was balanced by counter-flooding on the starboard side. “

The mines were massive explosions and caused extensive damage but no threat of sinking and no significant permanent structural damage.  In fact, the damage was repaired over the course of a few months.  These mines probably represented a worst case under-the-hull explosion of the type we’re interested in.

In a later attack, RAF Lancaster bombers attacked with 6-short-ton Tallboy bombs with 5200 lb Torpex D1 explosive.  A single hit on the ship's bow penetrated the ship, passed through the keel and exploded on the bottom of the fjord.  A thousand tons of water flooded the bow and caused a serious increase in trim forward but the ship did not sink.

Along with many bomb hits distributed over several aerial attacks which eventually sank the ship, Tirpitz absorbed three massive underwater explosions of the type we’re concerned with.  In fact, the explosions were probably much more powerful than a torpedo and yet they failed to inflict significant structural damage.

Prince of Wales / Repulse

PoW

-          torpedo hit on outer port propeller shaft exit causing extensive flooding and an 11 degree list to port

-          torpedo hit starboard bow

-          torpedo hit starboard alongside B turret

-          torpedo hit starboard alongside Y turret

Repulse

-          Four or more torpedo hits

Note that Repulse lacked anti-torpedo blisters and modern internal compartmentation.

Yamato

The Japanese battleship Yamato was subjected to multiple waves of attack.

First wave:

-          torpedo hit port side, forward which caused little damage

-          two torpedo hits port side near engine and boiler rooms

-          probably torpedo hit near auxiliary steering

Hits cause an initial list which was corrected with counterflooding.  Top speed was only slightly affected.

Second wave:

-          three or four torpedoes hit port side and one to starboard

This attack caused additional listing but did not put the ship at risk of sinking.

Third wave:

-          Three torpedo hits port side concentrated along the engineering spaces

-          Torpedo hit starboard

At this point, the ship began to sink.  In addition to the numerous torpedo hits, many bomb hits caused additional damage.

Musashi

Musashi was a Yamato class battleship that was sunk on 24-Oct-1944.  The ship suffered numerous bomb hits and the following torpedo hits.

-          1 torpedo starboard amidships which caused some flooding

-          3 torpedoes port side

-          4 torpedoes, three of which hit the forward bow

-          3 torpedoes starboard bow

-          11 torpedoes various locations

The ship sank intact.

Belgrano (Brooklyn class light cruiser)

The Argentinean cruiser was a 44 year old pre-WWII ship, poorly maintained, served by an ill-trained crew, and sailing with all watertight doors open when it was hit by three British 21” torpedoes.  The first exploded just forward of the armor belt and damaged the bow but did not threaten the ship’s stability.  The second hit just aft of the armor belt and opened a large hole which caused severe flooding.  Reports suggest that the third torpedo hit but it is uncertain whether it exploded.

None of the torpedoes broke the ship’s back and the first didn’t even hazard the ship.  The second caused flooding beyond the ill-trained crew’s ability to handle and led to the ship sinking.  It is likely that a well maintained ship, sailing at combat readiness (watertight doors closed), and with a trained crew would have been able to contain the damage and save the ship.

Bismarck

Prior to the action that directly resulted in the sinking of the Bismarck, the ship had suffered shellfire damage though the damage appeared to have no direct impact on the ship’s survivability.

On the evening of 24-May-1941, Bismarck suffered a single torpedo hit which caused only superficial damage to her armored belt.  Other reports suggest several torpedoes hit but did no significant damage. (1)

On the evening of 26-May a torpedo struck Bismarck’s port side and jammed her rudder.

On 27-May, British battleships and cruisers eventually wrecked Bismarck’s upper decks with the Bismarck absorbing as many as 500 shell hits. (1)  Torpedoes were launched by the British ships but the number of hits, if any, are unknown.  Two possible hits were reported. (2) 

Dorsetshire fired two 21 inch torpedoes and both hit the starboard side with no appreciable effect observed.  Another torpedo struck the port side, again with no visible effect.

Bismarck settled deeper into the sea and eventually capsized and sank.

In all, Bismarck suffered at least 5 confirmed torpedo hits and possibly 7 or more.  Other than to contribute to the cumulative flooding, the torpedoes caused no catastrophic structural damage.

HMS Belfast (light cruiser)

The cruiser Belfast struck a magnetic mine in November of 1939.  The ship suffered moderate damage and was repaired and returned to service.  Belfast was 613 ft long and around 11,000 tons displacement.

Photos of the ship in drydock suggest that the mine exploded under the hull, slightly offset to one side.  The explosion caused little direct damage to the hull, leaving a small hole, but did cause shock damage and warping of decks and structural members.  The keel was bent upwards by three inches.

The ship was, apparently, in no danger of sinking at any time.

This was a nearly classic example of the torpedo/mine exploding under directly under the hull and should have been a perfect example of the “broken back due to  suspension of the ship over a bubble” if the phenomenon were true.

Lexington (CV-2)

Two torpedoes hit the carrier on the port side but the ship was able to continue flight operations until a series of massive gasoline-sparked explosions occurred which eventually led to the ship being abandoned.  A US destroyer was ordered to sink the carrier and fired five torpedoes at which point the carrier settled into the sea on an even keel.

Princeton (CG-59)

During Desert Storm, Princeton suffered two bottom-moored influence mine explosions, one under the port rudder and the other under the starboard bow.  The explosions caused superstructure cracks and hull deformations along with various piping damage, shaft damage, and rudder damage but the ship’s weapons were back on line in 15 minutes.  The ship was able to leave the minefield under her own power.

Again, this was a near perfect example of the “explosion under the hull” and yet they did not break the ship’s back nor threaten the ship’s survival.  Further, this is a case of an explosion occurring under a modern, weakly built (as compared to a WWII ship of similar size) hull and yet still did not sink the ship.

Tripoli (LPH-10)

During Desert Storm, Tripoli suffered a mine explosion from a sub-surface moored mine which caused a 16x25 ft hole in the hull below the waterline.  The ship continued operations after damage control measures.

Again, this is a near perfect example of the underwater explosion effect and the results were negligible as regards ship survivability or even mission effectiveness.

Tripoli Mine Damage

Samuel B. Roberts (Perry class FFG)

A mine explosion blew a 15 ft hole in the ship and broke the keel triggering flooding and fires on multiple decks.  The mine is believed to have exploded in contact with the ship’s hull.  The explosion occurred on the port side at the forward end of the hangar.  Despite the near fatal damage, the ship was able to maneuver using thrusters at 5 kts and her combat systems and weapons remained operational.  The ship was saved, repaired, and returned to service.  Repairs took 6 months and cost $89M.

This explosion took place a bit to the side as opposed to directly under the ship and came as close to sinking the ship as any of the examples.  This is also the smallest ship in the examples and a modern, weakly built ship.  Despite this, the explosion did not break the ship in two.

_______

The observation that leaps out from an examination of the historical data is that no large ship has ever had its back broken by a mine or torpedo in the popular “suspended over a bubble of air” scenario.  Yes, a sufficiently large number of mines/torpedoes can cause enough cumulative damage (usually cumulative flooding) to eventually sink a large ship but none has ever been broken and sunk with a single mine/torpedo shot which is the commonly cited claim by the “torpedoes are invincible” crowd.  In fact, not only has no large ship ever been sunk by a single torpedo/mine hit but most have absorbed at least several such hits prior to sinking along with, in most cases, many aerial bombs which contributed to the sinkings.

It is also notable and, frankly, a bit surprising, that even smaller ships have been able to absorb surprising amounts of underwater explosion damage.  The 450 ft long, 4200 ton displacement Samuel B. Roberts was an example of such.

It must be noted that WWII torpedoes were not designed as under-the-keel weapons.  Most WWII torpedo hits impacted the side of the target’s hull somewhere in the lower half of the underwater hull depending on the depth setting of the torpedo and the draft of the target’s hull.  As such, these are not direct representatives of a perfectly placed under-the-keel explosion but they are informative data points, nonetheless.

There is also a school of thought that WWII weapons were not as powerful as today’s.  This is nonsense, as least as far as torpedoes and mines are concerned.  Supersonic, heavyweight anti-ship missiles are another issue but that’s a topic for another time.  Mines haven’t appreciably changed in terms of their explosive power.  Yes, fusing mechanisms have gotten more sophisticated but the raw explosive firepower has not.  The same holds true for torpedoes.  For example, the standard US torpedo of WWII was the Mk14 with a warhead weight of 643 lb.  The current standard US torpedo, the Mk48 has a 650 lb warhead.  They’re identical.

We previously disproved the commonly held belief that torpedoes kill by suspending a ship over a bubble of air and breaking its back.  The empirical evidence in this post further proves that the belief is a myth.  In fact, the empirical evidence suggests that ships can absorb far more underwater explosive effects than anticipated and that even destroyer and frigate size ships are capable of absorbing tremendous damage without structurally collapsing and sinking.

This post should not be read as a claim that torpedoes are insignificant - far from it.  They are powerful and damaging.  The smaller the ship, the more damage an underwater explosion will inflict – no great surprise – and, for smaller ships, such damage may well be fatal.  Still, all ships seem to show a surprising inherent resistance to underwater explosions. 

In part 2 of this post, we’ll examine one of the main, but generally unrecognized, factors behind this resistance to underwater explosions.

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(1)https://www.wired.com/2009/05/dayintech_0527/

(2)http://www.kbismarck.com/bismarck-last-battle.html

Chinese Type 071 Amphibious Ship

It’s always good to stay current on a potential enemy’s weapons.  Today, let’s take a look at China’s Type 071 amphibious landing platform dock (LPD).

The ship is 689 ft long, 91 ft wide, and displaces around 20,000 tons.  There are four ships of the class in service with two more planned or under construction.  Range is given as 6000 nm at 18 kts (2).

The Type 071 appears to be both a functional and visual equivalent of the US LPD-17 class.  The ship has a flight deck making up the aft 30% of the ship’s length and capable of operating two Z-8 troop transport helos simultaneously.  A hangar can accommodate four helos.  The ship also has a well deck that can house four Type 726 air cushioned landing craft (LCAC).  Side door/ramps located port and starboard below the bridge can also offload vehicles.  Troop carrying capacity is a battalion of several hundred along with storage for up to 18 armored vehicles (1). 

Armament is defensive and consists of a 76 mm gun and four 30 mm CIWS (2).

The ship has very slightly sloped sides but also significant vertical bulkheads and is likely to be only slightly stealthy, at best.  This is curious and somewhat flies in the face of modern naval ship design. 

Type 071

It is worth noting that amphibious ships are purely offensive assets.  This class plus numerous LCU/LST type vessels and the coming Type 075 amphibious class gives the Chinese a significant offensive amphibious capability.  China is clearly gearing up for major combat operations.  The question is who is this capability aimed at?  The obvious answers are Taiwan and the surrounding Pacific Rim countries and, ultimately, the U.S.  Another likely use is to gain control of key strategic locations in Africa.  As I’ve stated repeatedly and as China’s actions have demonstrated, China is intent on nothing less than global domination and has not hesitated to use the threat of military force to achieve that goal.  This enhanced amphibious capability will only increase China’s reach and intimidation.

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(1)War Is Boring website, “Five Ships Of The Chinese Navy You Really Ought To Know About”, Kyle Mizokami, 14-Dec-2013,

https://medium.com/war-is-boring/five-ships-of-the-chinese-navy-you-really-ought-to-know-about-22070c2264b7

(2)http://errymath.blogspot.com/2015/01/launch-of-4th-type-071-amphibious.html#.WgipltTytxA