CURV

Lore & Background

CURV was developed in the early 1960s by the Naval Ordnance Test Station in Pasadena, California. It was initially designed to recover test ordnance lost off San Clemente Island at depths as great as 2000 ft. CURV-III, the fourth generation, had an open metal frame measuring 6.5 ft by 6.5 ft by 15 ft, weighed approximately 5,400 lb, and was slightly buoyant in water. It carried two Vidicon television cameras, four mercury-vapor headlights, two mercury-vapor spotlights, and a 35-millimeter camera with a 500-frame color film capacity and strobe light, all mounted on two independent pan-and-tilt units with 360 degrees of lateral and 180 degrees of vertical movement. Other support systems included active and passive sonar, altimeter, depthometer, and compass. A tool assembly on the bow included a manipulator claw, and other tools could be mounted for particular tasks.

In 1973, CURV-III performed the deepest underwater rescue in history when it rescued two men stranded at 1575 ft in the submersible Pisces III after 76 hours with just minutes of air remaining. In 1976, CURV-III surveyed the wreck of the SS Edmund Fitzgerald in the Great Lakes, logging twelve dives in 500 ft of water with more than 56 hours of bottom time, producing 43,000 feet of videotape and 895 still photographs. After the Space Shuttle Challenger disaster, CURV-III was upgraded from 10,000 ft operations to 20,000 ft. CURV-21 is the next generation, built as its direct replacement. CURV-III was sent to the National Museum of the U.S. Navy in 2012 and is located in the Cold War Gallery.

Reader's Guide

CURV-III's significance lies in its role as a pioneer for teleoperation and its record-setting rescue of the Pisces III crew, which remains the deepest underwater rescue in history. The vehicle demonstrated the capability of remotely operated vehicles to perform critical tasks at great depths, including ordnance recovery, rescue, and wreck survey. Its use in the 1966 Palomares incident, where CURV-I recovered a hydrogen bomb, established the CURV series as a vital tool for deep-sea operations. The 1973 rescue of two men with minutes of air remaining highlighted the vehicle's ability to operate under extreme time pressure and adverse sea conditions. The survey of the SS Edmund Fitzgerald in 1976 provided extensive documentation of the wreck, though it could not determine the cause of its foundering. CURV-III's legacy continues through its successor, CURV-21, which was used in the 2023 search for the OceanGate submersible Titan. The vehicle's design, with its open frame, multiple cameras, and manipulator claw, set a standard for subsequent remotely operated underwater vehicles.

Did You Know?

• CURV-I became entangled in the hydrogen bomb's parachute lines during recovery, and the entangled bomb, parachute, and CURV-I were raised together.
• CURV-III performed the deepest underwater rescue in history at 1575 ft, saving two men with just minutes of air remaining.

Origins & Engineering Philosophy

CURV traces its roots to the early 1960s at the Naval Ordnance Test Station in Pasadena, California, where engineers set out to build a remotely operated vehicle capable of retrieving lost test ordnance from depths reaching 2,000 feet off San Clemente Island. The project quickly outgrew its narrow military purpose, establishing CURV as the true pioneer of teleoperated underwater robotics. By the time the third-generation vehicle rolled out, it carried an open steel frame measuring roughly 6.5 by 6.5 by 15 feet and weighing about 5,400 pounds, engineered to be just slightly buoyant so it could hover at depth. A surface support ship controlled the vehicle through a tether cable, while onboard sensors—including active and passive sonar, an altimeter, a depthometer, and a compass—gave operators a full situational picture. Two independent pan-and-tilt camera units provided 360-degree lateral and 180-degree vertical coverage, paired with mercury-vapor lighting and a 35-millimeter film camera. A manipulator claw on the bow, plus swappable tooling, made CURV-III a versatile workhorse rated for 10,000 feet of operating depth.

The Pisces III Rescue — A Race Against Minutes

In 1973, a Canadian commercial submersible named Pisces III was laying transatlantic telephone cable on the seabed off Ireland when a buoyancy tank was accidentally flooded. The vessel sank with its two British crew members, Roger Mallinson and Roger Chapman, trapped at 1,575 feet. Their life-support system was rated for 72 hours, a margin they stretched to 76 through careful conservation. After sister submersibles failed to reach them, a joint United States, Canadian, and British rescue operation was mounted. CURV-III was rushed 6,000 miles from its home port and deployed within a single day from the Canadian vessel CCGS John Cabot. Rough seas complicated the launch, a gyroscope failure and a short-circuit caused by green water forced rapid repairs, and the submersibles Pisces II and V had to assist. CURV-III managed to attach lifting lines to the trapped hatch. As the Cabot hauled the assembly upward at 60 to 100 feet per minute, the lines tangled. Operators cut free and abandoned CURV-III; the Pisces III floated to 60 feet where scuba divers secured new lines and completed the lift. The crew surfaced with only minutes of breathable air left, making it the deepest underwater rescue ever recorded.

The Edmund Fitzgerald Survey

In 1976, CURV-III became a household name in the Great Lakes after it was tasked with surveying the wreck of the SS Edmund Fitzgerald. Operating from the Coast Guard cutter USCGC Woodrush, with logistics handled by USCG Point Steel, the vehicle logged twelve dives in 500 feet of water, accumulating more than 56 hours of bottom time. The dives yielded 43,000 feet of videotape and 895 still photographs—enough visual documentation to reshape the official investigation. The survey confirmed that the Fitzgerald lay in a condition far beyond what normal commercial salvage could address. Observers noted more structural damage than had been anticipated, yet they could not pinpoint the cause of the foundering. Although the CURV-III team was fully prepared to recover bodies during the dives, none of the 29 crew members were located. An independent researcher was subsequently hired to analyze the survey material and produce the wreck sketches that appeared in both the United States Coast Guard and the National Transportation Safety Board investigation reports, cementing the vehicle's role in one of the most studied maritime disasters in American history.

From H-Bomb to Titan — A Legacy of Firsts

CURV's reputation was sealed in January 1966, when the first-generation vehicle helped recover a hydrogen bomb lost in the Mediterranean after a B-52 collided with a KC-135 tanker near Palomares, Spain. The Navy's DSV Alvin had located the weapon at 2,900 feet after a two-and-a-half-month search but could not retrieve it. CURV-I attached grapnels successfully but became tangled in the bomb's parachute lines; the entangled assembly was eventually raised to the surface 81 days after the crash. Decades later, following the Space Shuttle Challenger disaster, CURV-III was transferred to the Navy's Supervisor of Salvage and upgraded from a 10,000-foot rating to 20,000 feet. Its direct successor, CURV-21, inherited that deeper capability and was put to work in 2023 searching for the OceanGate Titan submersible. Meanwhile, the retired CURV-III found a permanent home in 2012 in the Cold War Gallery of the National Museum of the U.S. Navy, where it stands as a testament to four generations of underwater robotics.