SEAL Minisub: Reloaded

By Joe Buff — Defense Tech Undersea Warfare Contributor

Since at least the ’90s, U.S. Special Operations Command (SOCOM) has needed a stealthy, survivable, long endurance, shirt-sleeves-environment commando midget sub to be deployed/retrieved from the back of a full-size SSN or SSGN “mother ship.” One such project, the Advanced SEAL Delivery System (ASDS), got cancelled after years in development and at the expense of many hundreds of millions of dollars. The ASDS used an oddball (and as it turned out, inherently unsafe) rectangular cross-sectioned pressure hull, had a noisy screw, problematic batteries and an overburdened environmental control system. In late ’08, the single working ASDS self-cremated while its lithium-ion batteries were recharging at its special base (Hull 1’s homeport?) in Pearl Harbor.

Now, Teledyne Technologies’ subsidiary in Huntsville, Alabama, Teledyne Brown Engineering, has won a $383 million SOCOM competition to start over, 16 years after the ASDS program got started, to finish developing and then “manufacture and sustain” its Shallow Water Combat Submersible (SWCS) design. Teledyne Brown last year gave SOCOM a 1:1 mockup of the SWCS’s interior, and a hullform model, which were key to its success in the phase 1 competitive downselection.

Even basics of the ASDS design remained classified for many years, understandably so given the sensitivity of U.S. Navy Special Warfare ops. Pending more info being released on SWCS, such as authoritative renderings of the model’s insides and outsides, we can speculate about the design, in the sincere hope and stern expectation that every lesson possible is learned from the ASDS fiasco.

(The image above is a Navy concept drawing of the craft from a couple of years ago.)

A cylindrical pressure hull seems needed for reasonable SWCS operating depth, even at the cost of headroom and elbowroom; a different configuration of main screw, rudder, planes, and side propulsors seems likely; robotic grapnels ala NR-1 or research submersibles would have great utility; externally, the SWCS will not closely resemble the ASDS. Internally, any workable midget sub will need a control compartment, a midships (to manage center of gravity) diver lock out trunk (with pressure hatches both above and below?), and a warm, dry, 1-atmosphere compartment for the commando passengers and their gear.

Electronically, the SWCS ought to borrow as much as possible from the low-maintenance, high-capability Virginia-class non-hull penetrating photonics mast, and from that operationally successful, cost effective, delivered-on-time-or-better SSN’s awesome 2-man digital ship control station. In fact, the ASDS had a 2-man crew: one qualified Submariner and one Navy SEAL, cross-trained and seated side by side.

  • John Moore

    And I thaught things were tight with $ right now guess not.

    • Jason

      DoD > Feds

      Sorry to say, but the feds answer to the DoD. Flash forward……DoD for FY2013 is $563 Billion. $13 Billion INCREASE. Are you a noob when it comes to the Military-Industrial Complex?

  • JanZizka

    For christs sakes….they need to adapt the successful Swedish mini subs and save some money and get a system that actually works!

    Here we go again……

  • Dean Chapman

    In times of tight budgets, I feel it would be wise to investigate all options. R&D consumes so much time and money. Investigating ‘off the shelf’ or foreign made products that could be used and/or improved upon seems to me as a better way to go. Swedish mini-subs is a good example. Although they might not be mission perfect for US applications, as a base to build on, they would fit the bill. Think outside the box.

  • Franklin

    It looks lame to me. Shallow water is a joke. If its going onto the back of a sub it will have to be deep capable. The sub is not going to run in shallow water with this thing on its back. If the swedes have a cheap mini then thats the ticket. They should really have a craft that will run submerged then fly fifty miles with stealth, and then resubmerge for maybe ten miles. This isn’t rocket science, and they should be able to come up with something that doesn’t look like the Huntley.

  • blight

    Which Swedish mini subs? These?

    Apparently there was some consolidation, design now owned by a German company?

  • Lance

    Just update the current Mini sub.

  • Oblat

    Always fun to be at the start of another project death march.

  • blight

    “Thus SOCOM have decided on a less ambitious replacement craft which they call Shallow Water Combat Submersible (SWCS), essentially a modernized SDV. The SWCS has been discussed now and again for several years now.

    So far, so what. But now, in a request for information issued last month, SOCOM have said they’d like to hear from someone who can make them an “Integrated Bridge System” for their new mini-sub (that’s essentially a new comms/sensors/IT chassis, not a folding gangplank or something):

    The SWCS will require development of an IBS with an open architecture, a power and signal distribution system capable of integrating various electronic systems and sensors, and the capability to display operational data to the vehicle pilot and navigator.

    The IBS must address … the growing ability of hostile nations to detect, identify and target [special-ops frogmen] conducting undersea tasks. Thus, the SWCS shall have a modular subsystem design conducive to accommodating upgrades to processors and sensors. Operating in a free-flooding “wet” vehicle, the SWCS passengers and crew transit for extended durations (up to 12 hours) in a wet, variant temperature environment while breathing from SCUBA gear. Thus hardware and software selected must feature interfaces that ensure required operator actions are simple and minimized.

    The SOCOM planners give a list of things they want the new frogman-carrier’s data handling system to do, giving some interesting insights. They’d like the minisub pilot to know if he was being scanned by hostile sonar, for instance, or (if on the surface) by radar: the IBS should offer the option of plugging in “passive sonar, and ESM [Electronic Support Measures – radar detectors, to you and me].”

    The current SDVs navigate underwater using seabed-scanning doppler sonar, as satnav signals can’t be used when submerged. Unfortunately, a sophisticated enemy can use the sonic pulses emitted by the Mark 8′s nav sonar to detect it. SOCOM would prefer the future SWCS to feature inertial navigation.

    Apart from this, the new mini-sub should if possible feature wireless through-water comms of the sort now used by civilian divers, and must have a soundless, secure option using wires too. The ability to download mission data wirelessly when docked aboard the mother ship is desirable, but a hardwired umbilical mode is also fine.

    It would also be nice if the SWCS’ on-board computers and controls were clever enough to bring it in for automated docking without help from divers. This would put slightly less strain on accommodation aboard the mother sub. There are some specially-converted former ICBM vessels specially intended to carry a force of SEALs, but where the dry deck module is fitted to an ordinary attack boat the SEALs and docking-bay divers have to “hot bunk” – take turns sleeping – with the submarine crew.

    Finally, the info request reveals that the SWCS will feature an extend-able “sensor mast … allowing the Plug-n-Play integration of various imaging sensors” (periscopes are so last century) and the IBS data system should obviously allow for recording these images and displaying them to the minisub’s crew.

    All the cunning minisub electronics needs to work at depths of at least 190 feet, ideally as much as 300 feet, and it should be 95 per cent reliable over 15 twelve-hour missions.

    British readers may care to note that Her Majesty’s equivalent of the US Navy SEALs – the Special Boat Service (SBS, the maritime SAS) – also currently use the Mark 8 Mod 1 SDV and will probably follow the SEALs onto SWCS in due course.”

    There’s a lot of overengineering at work..

  • Brian

    If malpractice could apply to journalists, this author would be guilty. SWCS is not a replacement for ASDS, but rather for the SDV (Seal Delivery Vehicle). Even the press release ( does not claim the vessel is a replacement for the ASDS. Per… the SWCS is a free-flooded system. ASDS had a dry interior. In fact, ASDS was originally procured because of the perceived need for a delivery vessel with a dry interior for the SEALs. The author’s comparison of the “pressure hull” is void when one vessel does not have a pressure hull. His speculation about what attributes the design “ought” to have is irresponsible when he has zero information about the actual design except for the price. Thorough analysis would show that the author’s dream design would cost much more than the price of the contract awarded to Teledyne, which is irresponsible when he presents the cost of ASDS as excessive in the same article.

    • blight

      As an aside:

      “” “Our development efforts are focused on a free-flooding SWCS that requires no external diver delivery system modification,” Capt Sullivan said at the AUVSI unmanned systems program review conference in Washington DC. “”

      It seems like the guy assumed that due to its shape that it would be a dry setup. However, the present SDV superficially looks like this.

      The links I posed to Sea Dagger and the Andrasta refer to legit minisubs, and I suspect the Sea Dagger is something more akin to what the author was thinking about.

    • C.E.

      I agree with you Brian. Joe’s comment “The ASDS used an oddball (and as it turned out, inherently unsafe) rectangular cross-sectioned pressure hull”, is a major screw up. Joe is either an idiot or he is deliberately attempting to mislead those ignorant of the actual ASDS design. Personally I think that Joe knows better but is being opportunistic. From the outside ASDS appears rectangular because of the external panels (cowling if you will), surrounding the pressure hull which are flat. I assure you that the pressure hull underneath is indeed cylindrical. To me there is an obvious bias in this article. I think that the article has exposed Joe’s ability to willingly avoid objectivity in favor of a play for the stage.

      • anon

        You have got to be kidding me…butthurt much?

  • Joe Buff

    Guest: Good question! Teledyne’s Media Contact (listed on their press release that essentially verbatim became the UPI wire service article picked up in the media)
    was unable (yet) to return my voicemail earlier this week asking for any more UNCLASS info on their internal mockup etc. The AviationWeek item that Blight helpfully posted above is dated 7 March ’08, about an unmanned undersea vehicle conference the week before then. The full item discusses both the SWCS and some UUV programs. It says the SWCS project was meant to replace the free-flooding SEAL Delivery Vehicle. Some of the interesting blog comments posted there suggest some ongoing confusion re SDV vs. ASDS. My piece on DT above tried to focus on lessons to be learned from ASDS for a “wish list” SEAL undersea transport vehicle. This whole fascinating and vital (and controversial) area can easily fill whole books. Alas the DT word count limit is just a few hundred words! Which is the great value of the Comments give-and-take.

  • Greg C

    I could design, build and demonstrate a vehicle like this for a fraction of the cost.

  • Sandy

    Interesting posts. I was the first SEAL Co-pilot of the ASDS for 5 years including being the department head until early 2002. Amazingly, NAVSEA and SOCOM are trying to reinvent the wheel after the first vehicle was lost due to the new L-ION batteries. Interestingly, they have not asked any of the original guys for lessons-learned.