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Corvettes Versus Midget Subs

June 2, 2010

Japanese Type D ("Koryu") Midget Submarines captured in 1945.

The Inevitable, Mythical Corvette

This ongoing proposal for small warships is instigated by recurring problems which keep revealing itself to the surface navy. Now that we see an increasing rise in the threat of so-called midget submarines, as in the sinking of South Korean warship Cheonan, it is also an attempt to avert fostering yet another mission off on the world’s most powerful and most expensive surface combatant, the Arleigh Burke destroyer. Sadly, the $2 billion Burke has become the Navy’s workhorse, with its few frigates and patrol craft aging rapidly and the littoral combat ship unlikely to enter service in significant numbers for another decade, if then.

Here is the need–I have mentioned North Korea which deploys over 30 midget submarines. There is also the home-built drug subs designed by the South American cartels, which recently the Royal Navy sent a lone guided missile destroyer, HMS Manchester, to contend with. Here is the story from the UK Telegraph titled “Royal Navy launches anti-sub war against drug cartels“:

More than 1,400 tonnes of the drug is smuggled across the Atlantic every year but despite a sixfold increase in interceptions only 3 per cent (43 tonnes) was seized last year.
It is estimated that 20 tonnes of cocaine is enough to “kill every school child and pensioner in the UK”
But with counter-narcotics currently the third priority after hurricane relief and military training (Rear Admiral Mark Anderson, commander of Fleet operations) admitted it could be “in the national interest to run a ruler over it again.”
Cuts to the Navy have forced it to have a presence in the Caribbean for only six months of the year.
We need some presence to push the problem ever harder into Caribbean traffickers,” the officer said.

If cuts have reduced the RN’s presence in the Caribbean, then obviously she needs more ships, and these should certainly be less expensive than the Falklands War era HMS Manchester. Again like the American Burke you are sending an advanced warship, vitally needed elsewhere, so much overkill battling homemade warships, vessels less than 1/20 the size of a destroyer and a fraction of the cost. Strategypage reveals more of the unique craft, also known as semi-submersibles:

It’s estimated that about 75 of these subs are being built in northwest Colombia each year, and sent on one way trips north. Each of these boats carries a four man crew and about seven tons of cocaine…

Between 2000 and 2007, 23 of these boats were spotted. But last year, nearly 70 were seen or captured. Many of the captures are the result of intelligence information at the source, not air and naval patrols out there just looking for them…Despite increased efforts, it’s believed that less than ten percent of these subs have been caught.

The antisubmarine corvette, in contrast to the stretched thin and overworked missile battleships, should be less well armed but very adequate for the mission entailed. No helicopter would be necessary since it will operate in conjunction with other aviation ships (or even long-range planes and UAVs which have greater staying power and endurance than helos), but it does need sonar and sub-killing torpedoes. The key would be to make them affordable enough to acquire in numbers and perform the presence part which a handful of billion-dollar destroyers and frigates can never do.

Since midget subs are silent, deadly hunters, as we see in the Cheonan sinking, it needs a silent, deadly counter. Earlier, New Wars posted an idea from Carlton Meyer for just such a craft, the Diesel/Electric Corvette:

Surprisingly, no navy has constructed a DE ship that can switch to quiet electric propulsion when hunting submarines.  This does not require the development of new technology, DE engines already exist on submarines.  A small ship is best for submarine hunting as they are quieter, harder to see on the surface, more maneuverable, and a smaller target for submarines.  While cruising slowly on electric power, a DE ship will produce no heat for detection at night or in poor daytime weather, which submarines may detect with infrared periscopes.  A DE corvette is an ideal size for a sub hunter, with a displacement of less than 1000 tons…

Instead of wasting a single high value asset such as a destroyer, frigate, or even the $700 million LCS, numerous ASW corvettes will swarm once the target is identified. If an aerial threat is considered imminent, then here is where a nearby anti-air warship, even a corvette so armed would prove handy to defend the force, but only in small numbers. 

For replacing ships which are harder to build, increasingly impossible to acquire in adequate numbers, small warships like the corvette seem the right fit. With prices starting at $50 million each, you could afford a whole fleet of corvettes for the price of a single Burke. As we noted you don’t have to give up this high value asset, only diverting it to functions more suitable to its immense capability. With increased numbers in the fleet, instead of a token, almost symbolic-only response to emerging threats of Third World navies, you could have a real impact and return of presence.


Columbian drug-smuggling semi-submersible.

13 Comments leave one →
  1. Juramentado permalink
    June 3, 2010 8:58 pm

    Mike – much like Naval Aviation changed the face of sea combat in WW2, Maritime Surveillance is the key to solving much of the asymmetric warfare problem on the oceans today, like pirates and drug runners. It doesn’t make the ship any less valuable. As Hokie pointed out earlier, you need the ship to prosecute the contact. But that doesn’t mean the ship is the best Detection or Classification method. This is very much a combined arms methodology. The Army wouldn’t send tanks into urban combat without infantry to protect the flanks and rear. But to root out the enemy, you need both, working together.

    In the same way, if you have to cover 400,000 square miles (that’s the Somali coastline out to 200 miles into the Basin), you can’t do it using ships alone. All the surface assets of every major navy in the world (including tugs and barges) could be deployed, and they’ll still have gaps in coverage that the pirates could slip through. And they’re bigger radar and IR targets than SPSS. It’s that insurmountable a problem if you choose surface or sub assets only. The attacker has space on his side, but imperfect ideas as to where the defender is actually located from a surface asset placement. This is why sometimes, ships are in the right place to intercept. But more often than not, they’re out of position. But put a surveillance system in place, and start to sort the targets, classify the wolves from the sheep, and you can start to put surface assets in the right place to prosecute.

    I understand your concerns about COIN, but even COIN strategy works the same way – you need actionable intelligence in order to focus your combat power on the bad guys. If you disperse your troops to try to increase presence everywhere, you’ve diffused your combat power – instead of being able to bring a platoon or even a company to bear, you’re now have to make do with a squad, which may not be big enough a stick. That actionable intelligence is gathered by many means, but one of the most effective technical methods is by aerial surveillance. Just look at how UAVs have proliferated in the SWA theater. It’s not a fluke.

  2. hokie_1997 permalink
    June 3, 2010 8:44 pm

    I just can’t imagine how you reach these conclusions. wargames?


    Analysis, Mike — and not just blanket statments with no analytical or historical rigor. This problem has been looked at thoroughly and objectively.

    I can make these statements as a former P-3C NFO who has actually flown counter-drug and counter-piracy missions, so I know a little about martime surveillance.

    What you can’t or won’t hear is that commanders are not screaming for more ships in the Horn of Africa. They want more surveillance so they can use their small numbers of ships more effectively.

    FYI — here’s a snippet on BAMS:

    I’m reminded of the adage “If all you’ve got is a hammer, every problem looks like a nail.” In the case of this website I’d consider: “If all you want are small vessels, every problem looks exactly suited for small vessels!”

  3. Juramentado permalink
    June 3, 2010 7:58 pm


    Hokie and I are not making this up. Why do you think the bulk of air assets in JITF South besides helos are AEW and MPA? A good bulk of Coast Guard catches in South Florida and the Eastern Pacific are due to MPA patrols. Honestly, there is a major difference in operational doctrine between COIN – your viewpoint -and maritime security. Don’t mistake the two. They are interrelated, but distinct in the case of SPSS use. That NPS study is now part of doctrine for JITF South so this isn’t hypothetical.

  4. Mike Burleson permalink*
    June 3, 2010 6:21 pm

    Hokie wrote “In terms of endurance and persistence, 3-4 BAMS can provide on-station coverage 24/7 over a enormous chunk of water indefinitely.”

    I just can’t imagine how you reach these conclusions. wargames? But I pointed out to you the lessons of war, and the lessons of our recent land campaigns suggest our plentiful airpower has been ineffective in the absence of plentiful boots on the ground. So it is with the ongoing anti-piracy struggle with the commanders on the scene virtually admitting defeat before these Third World adversaries who just move to a new area when our frigates arrive on the scene.

    You can’t get past the principals of seapower that you can’t maintain control with battleships alone, and to these speedboat, fisherman navies, our frigates are like battleships, easily outmaneuvered or outnumbered.

    Exquisite aviation-capable ships cannot replace the flotilla, and I’m watching this obvious truth play out in the Gulf.

  5. Juramentado permalink
    June 3, 2010 1:31 pm

    Hi Gents,

    Per request – a link to CDR Pfeiff’s study entitled “Optimizing employment of search platforms to counter self-propelled semi-submersibles.” It’s all open-source, unclass and above-board.

    Standby for some heavy duty number crunching. I will be the first to admit skinny class was not my finest moment, but if you keep the parameters in general terms rather than trying to work through the math, it’s a very solid write-up – personally, some of the best Operational Research I’ve read in a while.

    The most telling conclusion (I may be spoiling it for some here) is given two scenarios (E. Pacific and Carrib) where you have one of each: AEW, MPA, frigate w/tail/helo, sub and a hypotehtical mini-SOSUS, the removal of the MPA in each dropped the Detection-Classification ratio down significantly, whereas any other factor was not so dramatic – in some cases very negligible.

  6. hokie_1997 permalink
    June 3, 2010 1:03 pm


    And the thing about ships is they can’t see very far or move very fast!

    I don’t think we’re talking about sea control — we’re essentially talking about martime security. This is fundamentally a detection and classification problem. Once you’ve found the bad guys, a very small number of low-end ships is all you need for the takedown.

    In terms of endurance and persistence, 3-4 BAMS can provide on-station coverage 24/7 over a enormous chunk of water indefinitely. How many corvettes do you think you would you need to do the same?

  7. Mike Burleson permalink*
    June 3, 2010 11:28 am

    Juramentado-The thing about using airpower alone for sea control, is they lack endurance and presence. Certainly LR aircraft have great endurance, and UAVs can stay up for days, they still can’t match even a small warship or USCG cutter which can stay at sea for many weeks and months.

    The numbers of submarines caught in a single year is astonishing. Did you catch the figure of 70 hulls, and those were just the home-built vessels that were caught? Thats warships off the shelf.

    The number of aircraft are shrinking, with all their high tech and extreme cost, but the requirements for sea control remain the same. Even at the height of the campaign with the U-boats, when there were thousands of planes coming off assembly lines per month, there were also hundreds of small craft built annually for escorting convoys, hunter killer groups, and blockade duty.

    So we see from the lessons of war, that airpower certainly enhances the ability of warships, but cannot replace them. Instead this is the lessons of about 70 years minus a major war at sea.

  8. hokie_1997 permalink
    June 3, 2010 11:18 am


    You stole the words right out of my mouth!! Do you have a link to that NPS study?



    Need I remind you that developing capabilities and force structure to guard against any scenario is what got us LCS?

    In terms of applying the lessons of COIN to ASW, I’ve long maintained that this is a tenuous comparison at best. It’s a gross oversimplification of both ASW and COIN — but I’ll play along.

    ISR is a pretty key element to any COIN strategy. We don’t have the resources to put troops everywhere to watch every village, bridge, road junction to detect insurgent activity. So we rely upon airborne ISR to survey large swaths of territory and provide cueing so that we can better focus our resources.

    Same goes with ASW — at least as pertains to the SPSS threat. We can’t afford to enough corvettes to flood the ocean, so rely upon land-based MPA to provide large area detection and cueing. Use existing naval vessels as pouncers for the VBSS takedown.

  9. Juramentado permalink
    June 3, 2010 9:24 am

    “The defender has to be strong everywhere, or at least as much as possible.”

    Mike – this is exactly why Hokie and I advocate the use of MPA and AEW primarily. The area of maritime domain awareness is too large, whether you’re talking about the Caribbean or the Somali Basin. You will lose the game of interdicting and stopping the bad guy’s activities if you choose the “strong everywhere” approach. You do not have enough assets to make it possible, even if ship manufacturing reached WWII peak levels. It’s a zero-sum game. You have to play to the defender’s strengths, not the attacker’s.

    In the Caribbean, you don’t need to be strong everywhere. Like I said, think natural chokepoints. They either make the transit through the Windward Passage to reach South Florida or breakout to the Atlantic, or use the Yucatan Channel to try and land the shipments in Mexico or more rarely now, the Louisiana or Texasa coastlines. They will avoid any other routes because those areas are too heavily travelled by merchant and leisure shipping. Put ships in or near those chokepoints. Use AEW and MPA to find and classify the SPSS at long range and track-trail. Guide your slower ship assets or short-legged helos to the expected interception point. Bob’s your Uncle. It sounds simplistic, but this has been scientifically taken apart and proven. If you’re interested in seeing the numbers, let me know, I can point you to the open source intel.

  10. Mike Burleson permalink*
    June 2, 2010 1:21 pm

    Hokie asked “why is the solution always more ships?”

    To plug the gaps, which is something we learned in the world wars. Even with plentiful aircraft, far more than we possess today, you still needed ships to guard against any scenario. Like the insurgent on land, the submarine gets to choose where he can strike. The defender has to be strong everywhere, or at least as much as possible.

    Aircraft are to enable warships on the scene, but like the boots on the ground airpower cannot replace hulls in the water. Thats why the pirates and drug dealers are winning. Apply the lessons of COIN on land to the sea and you will see a change.

    Technology will never defy the principles of seapower, anymore than they have on land.

  11. June 2, 2010 12:59 pm

    > get Nimrod MRA4 on-line

    I’d do everything possible to opt for something like the Guardian Twin Otter that Vietnam is buying. One can buy some of them and operate them mostly with contractors for the overall cost of deploying Nimrod. Most of the support infrastructure will be already there, waiting with open hands. Combine that with live and computerized satellite monitoring and the sub guys will get tired of being sub-surface all the time.

  12. Juramentado permalink
    June 2, 2010 12:27 pm

    I have to agree partly with Hokie_1997. Get a copy of CDR Pfeiff’s NPS Thesis on detecting SPSS and you’ll see the matrix answer in constrained areas like the Carrib are the MPA and the AEW platforms for maximum coverage. Note one is better at detection and the other at classification. The Kill Chain requires Detect-Localize-Classify. Especially in high density traffic patterns, classify is the key, otherwise you’re burning fuel oil or avgas chasing all sorts of contacts that may or may not be the target of interest.

    The other aspect to think about is the geography – slow moving platforms like ships (relative to aerial assets) are better at servicing natural chokepoints. The good news is that there are only several places in the Carrib where you can get to the ultimate goals (US coast or Atlantic breakout). Those ships should be helo-equipped though to be able to respond quickly and effectively to a high-confidence target.

  13. hokie_1997 permalink
    June 2, 2010 11:15 am

    Mike wrote:

    “If cuts have reduced the RN’s presence in the Caribbean, then obviously she needs more ships, and these should certainly be less expensive than the Falklands War era HMS Manchester.”


    Mike, why is the solution always more ships?

    I’ve always thought that ships are an inherently inefficient and ineffective solution to detecting submarines. Localizing and killing them – yes. But open water detection – not so much.

    The semi-submersible threat is at its core a DETECTION problem. Once they’re found, all one needs is a law enforcement/Coast Guard vessel to do the VBSS.

    If you need broad area detection and cueing, long-range aircraft are probably a better solution. US Navy, Coast Guard, and Customs martime patrol aircraft (MPA) have been very effective in detecting semi-submersibles with radar and EO/IR.

    Conidering the plethora of airfields in the Caribbean basin, I think the push should instead be for the RAF to get Nimrod MRA4 on-line and set up a permanent det in the British Virgin Islands.

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