The French at DCNS seem to feel ready for experiments. The SMX-25 concept appeared in the internet a few days ago and is about a coastal waters submarine with an extreme surface speed.

photo: DCNS
109 meters submarine, 2850 tons conceived to operate in short depth (100m max.), would have a speed of only 10 kts in depth but 38 kts at surface. Fitted out with some torpedoes but mainly anti-ship missiles, and unnamed helicopters. Kind of a light stealth frigate / submarine mix.

I'm not sure what this surface speed may be good for (same mystery as with the LCS), and it reminds me a lot of the Engelmann Boot VS-5 (which were not actual submarines, though).

We might see more about it on the Euronaval 2010 exhibition.


  1. That's an intersting point indeed: which tactics would ligitimate the need of a highspeed vessel in the missile age? Is it to cruise into your operational area or missile range rather quickly and to make a fast withdrawal after your mission is completed? I always thought the LCS speed requirement was due to small boat interception missions in an asymetric scenario - which you don't seem to be a friend of anyway.

  2. Its an interesting concept, one I'm surprised hasnt ever really been done before. I'm curious to see the thinking behind it(beyond the obvious).

    Agree with the speed too, its just not an increase thats relevent to a jet or a truck, and the range penelty must hamper it in a naval setting.
    It just doesnt seem like an ability the French would ever need.

  3. Im struggling to think what role it would fulfill outside of a niche Fast attack craft substitute.

  4. Sorry I am taking the speed issue up again but I remembered a passage I read in Hans Frank's "Deutsche Schnellboote im Einsatz - 1956 bis heute,121 ff.". There is one factor a small cramped boat, a compact crew and just the high speed were quite essential for: motivation. You wrote some time ago that a "Vorpostenboot" like vessel that is simple and slow is not enticing enough for some theorists. But what about enticing its crew? But admittedly I am not shure if the increase of fighting spirit is forth the disadvantages high speed involves.

  5. I think it means to say "Unmanned helicopters".

    Other than that maybe I am just pointing out whats obvious to anybody else, but isnt this actually an LCS for low-and medium-intensity warfare that, in contrast to most of the current procurements, can also actually engage in any kind of "real war", ie. between technological peers by means of its capability to evade enemy surveillance and effectors (ie ASHM). The low depth and limited speed clearly indicate to me, that this ship is supposed to be a medium sized surface vessel, ie. light frigate, that will operate mainly above the waterline and use its submergingg capability as a means to escape enemy detection or to seek an advantage in a specific tactical situation. Its a frigate with submerging capability, not a coastal submarine that sometimes operates on the surface with extreme speed. I have to see more hard numbers on it, but it also does not strike me as primarily a littoral craft, rather a combined blue-and green water-asset (ie. LCS, any kind of MEKO light frigate).

    The first thing that came to my mind when I saw this concept was Keegans thesis that pretty much all aspects of naval warfare will move underwater.

  6. Para
    I agree, its a submersible frigate, not a, erm, merasble submarine, the question remains, why can it go 50% faster than most current frigates?

  7. Nice idea, this submersible frigate, it offers the best low observeability possible.
    The quoted speed on its own doesn't make sense. For the LCS for example it's known that these ships don't lose much speed when turning. So if you fire a missile on a ship that releases decoys and jams you, you'll need a very wide arc to retarget it after it evaded you through a maneuver. The most likerly reason is that the missile was still locked on the original ship position taken up by a decoy or that the ship followed some airborne decoy moving in a different direction than the originally targeted ship (RN, Falkland War trick). The faster a ship is, the less time it needs to be out of range of missile impact point on which the enemy missile is locked on. The faster it evades this point, the less warning time it needs. That's very sensible if the enemy can fire something very fast from a very short distance. So current naval developments do make sense, but I don't know if increased speed is the best solution to rapidly appearing threats that leave little reaction time.