From the glory wall in my office at the WWM.

Context and Precedence –  One component of Naval Special warfare that the public and sometimes the military overlooks is the SEAL Delivery Vehicle Teams. SDV Teams are considered National Asset Teams and are Tier 1. SEAL Delivery Vehicle Teams specialize in three primary mission sets: underwater insertion and extraction of special operations troops, underwater special operations, and underwater/maritime special reconnaissance.

The SEAL Delivery Vehicle is a manned submersible and a type of swimmer delivery vehicle (water inside, not dry) used to deliver United States Navy SEALs and their equipment for special operations missions. The SDV, which has been in continuous service since 1983, is used primarily for covert or clandestine missions to denied access areas. It is generally deployed from the Dry Deck Shelter (DDS) on a specially-modified attack or ballistic missile submarines. Teams of SEALs are specially trained to operate the submersible on dives that can last up to 12–14 hours utilizing multiple UBAs (underwater breathing apparatus) scuba, closed circuit, and mixed gas.

In the event of a conflict with China, for example, SDV Teams could transport SEAL operators close to enemy harbors or to other strategic targets, such as the Anti-Access/Area Denial (A2/AD) that can prevent U.S. Navy aircraft carriers from getting within range. SDVs are able to unilaterally attack enemy warships in a harbor by placing limpet mines, or other explosive devices on ships or detonating other devices that would block the entrance and stop or stall traffic. Finally, SDVs are able to operate close to enemy shores, emplace sensors, and reconnoiter before sending vital intelligence back to headquarters to inform commanders.

New Platforms – I don’t think that the new MK-11 SEAL Delivery Vehicle is much of a secret.  It’s the new shallow water mini-sub that is slated to replace the US Navy’s MK-8 SDV.  Clearly, the operational details of the sub will be classified. As with the MK-8, everyone in the submarine is “wet” and breathing either O2 from a Drager-style unit or compressed gas.

As this blog’s readership may be aware, I served as an officer at SDVT-One some thirty years ago (time flies), so I am generally interested. in the development of both the newer wet SDVs and a dry SDV that will be coming online in the future. The Advanced SDV (ASDV) program was canceled some years ago and the new dry sub is different than that one.

The Incident –  A new MK-11 SDV, collided with a fixed object on October 24 while underwater.  Nobody was injured. Naval Safety Command listed the SDV collision as a “Class A” mishap, which connotes damages of more than $2.5 million.

Having been in the business, I’d bet you a really good hamburger that I could come close to telling you what happened since I’m an old armchair shallow-water submariner. I’m not going to do that, but the operating environment that the SDVs can operate in – harbors and so forth – is full of obstacles. Nobody asked for my input on the new SDVs but from the design, much of the old MK-8 engineering was retained. Teledyne-Brown stretched a MK-8, adding a new propulsion plant and a new sensor suite, but some of the flaws may remain.

JSOC (parent command for NAVSPECWARCOM) is content to throw money at these SDV projects because they do have value. If it was Big Navy money, they’d be far more parsimonious. SEAL programs pre-JSOC and post-JSOC – essentially placed under the control of the US Army were like night and day. The Army didn’t mind spending money and the big deck admirals (black shoe) and airedales (brown shoe) held a certain disdain for the camouflage navy.

You know that somebody had his ass on a plate for breaking the submarine because it’s the Navy. I can only hope that they learn instead of just persecuting people and that Teledyne Brown changes the design to better fit operational realities.


  1. I like the shark fin. Adds a touch of flair and ‘FOAD’ to an otherwise humdrum shape.

    As to the expense, well, I guess the ooold ooooold days of repurposed torpedoes are long gone.

    Hmmm… Interesting thought, wonder if there are unmanned, payload carrying drone versions of the SDV? Quiet way to mine an enemy harbor or even blow up a harbor. One loaded with explosives under a ChiCom flat-top would send said flat-top flying.

  2. Funny how having that little J in front of your organization meant a much larger budget and good equipment. When I transitioned back into the regular Air Force as a shop supervisor I had 6 tech school only technicians and our only piece of equipment at Depot being rebuilt for 7 months. When it finally showed up it was my first piece of equipment when I was in the Joint unit and it was new. We turned it over for newer equipment 8 years before I went back to regular Air Force and I got it back as a rebuilt hand me down.

    • The “J” means big funding. And there are a lot of guys wearing both Budweisers AND stars these days. It didn’t used to be like that.

  3. Without asking for any classified information, are the SDV’s quiet? Hard for sonar to detect? I hope so, any kind of depth charge would be most unpleasant for the operators.

    A cousin was UDT circa early 1960’s. We don’t like each other but I respect his service.


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