SUBDEVGRU ONE sends 13,000-pound tools to cut cables 20,000 feet down
By Marcus Boone ·
National Geographic photos of a shipwreck mask a deeper mission: using a 13,000-pound robot with a rotary saw to perform unspecified work in the crushing dark of the ocean floor.
It weighs 13,000 pounds and is designed to operate in a place where the pressure would crush a human being instantly. The Advanced Tethered Vehicle (ATV) is not a free-swimming drone; it is a captive asset, bound to the surface by a 23,000-foot cable composed of power conductors, fiber-optic signal conductors, and a kevlar strength member.
According to a program page mirrored by the FAS Intelligence Resource Program, this vehicle is capable of descending to depths of 20,000 feet. While the public record defines a tethered balloon as a craft restrained by a winch to prevent it from floating away, the ATV is the inverse: a heavy-duty tool restrained to ensure it can be controlled, powered, and retrieved from the crushing dark of the ocean floor.
A Rotary Saw at 16,650 Feet
The ATV is described less as a camera platform and more as a mobile workshop. Its "work package" includes a pair of TV cameras on a pan-and-tilt system to provide 3-D views, but the hardware that follows is far more aggressive. The vehicle is equipped with two master-slave manipulators that provide force feedback to the operator, allowing for a tactile sense of touch at miles of depth.
The toolset is specific and industrial. It consists of a spreader, a drill motor, a wrench, and a rotary saw. There is also a grabber on the work platform, intended to keep the vehicle stationary against the objects it is manipulating. When the Navy needs to cut through something or pry something open at the bottom of the sea, they do not send a scientist with a net; they send a 13,000-pound robot with a cable cutter and a jack.
For navigation and target acquisition, the ATV relies on two types of sonar. A CTFM sonar (EDO Model 259) provides a 2,000-foot range, while an obstacle avoidance sonar (Wesmar RVS 1200) covers 1,600 feet. This allows the operator to steer the craft—which moves at a sluggish 1.5 knots forward and aft—through the lightless terrain of the abyss.
Document imagery from irp.fas.org From the files: irp.fas.org
February 1993
The origin of the ATV is a trail of specialized laboratories. It was designed and built at the SSC San Diego's Hawaii laboratory as a follow-on to the Remote Unmanned Work System (RUWS). After undergoing testing and evaluation at NRaD San Diego alongside the Advanced Unmanned Search System (AUSS), the vehicle changed hands.
In February 1993, the ATV was transferred to the Submarine Development Group One (SUBDEVGRU ONE) in San Diego. While the SSC SD continued to provide re-engineering and new fabrication of components, the operational control moved to a unit specializing in the development of submarine capabilities.
The FAS mirror notes that the ATV serves as the Navy's unmanned deep-water asset on the west coast. It is the Pacific counterpart to the Cable-controlled Undersea Recovery Vehicle (CURV III), which handles similar duties on the east coast. This creates a symmetrical capability for the U.S. government to intervene in the deepest parts of both the Atlantic and Pacific oceans.
Document imagery from irp.fas.org From the files: irp.fas.org
Who owns the bottom of the Pacific?
There is a curated image of the ATV as a tool for exploration. The record highlights a mission in May 1998, where the vehicle assisted the National Geographic Society. Together, they located, mapped, and photographed the wreck of the USS Yorktown, a World War II aircraft carrier resting 16,650 feet below the surface.
For the National Geographic project, the ATV’s high-end optics were the star: a 35mm still camera (Photosea 1000A), a strobe system, and a variety of Osprey and Sony color video cameras. The presence of "four HMI lights" and "two 250 watt incandescent lights" allowed the team to illuminate the carrier's hull for the cameras.
But the National Geographic mission is a secondary detail in the broader context of the vehicle's existence. The ATV was not built for photography; it was built for "work." The 200-pound payload capacity and the force-feedback manipulators are not requirements for mapping a shipwreck. They are requirements for recovering objects, cutting cables, or manipulating hardware on the seabed—tasks that fall under the purview of SUBDEVGRU ONE.
When the Navy lends its most capable deep-sea asset to a scientific endeavor, the resulting images are the only thing the public sees. The record, however, lists a different set of priorities. Beneath the color video cameras and the strobe lights, the ATV carries a hydraulic connection and an unpowered line reel containing 16,000 feet of 3/8" kevlar line.
The document leaves the specific nature of the "work" performed by SUBDEVGRU ONE outside of the Yorktown mission unspecified. It simply lists the capabilities: a drill, a spreader, and a cable cutter, all accessible via an RS 232 interface.