Strange craft at Pillar Point used to photograph underwater ship wreckage

The recent appearance of a “yellow submarine” at Pillar Point Harbor near Half Moon Bay has charmed and intrigued locals and tourists, but you might not want to call it a submarine.

Submarines carry people, said James Delgado, director of maritime heritage for the National Oceanic and Atmospheric Association, but the Echo Ranger is unmanned and thus should be referred to as an Autonomous Underwater Vehicle (AUV).

The seafaring drone came to town for a mission that began Monday morning. Traveling at a mere 3 knots [about 3.5 mph], and accompanied by the research vessel Fulmar, Echo Ranger journeyed 30 miles out to sea, where it captured high-definition, 3D sonar images of the USS Independence, a groundbreaking World War II aircraft carrier that was intentionally sunk near the Farallon Islands during torpedo warhead testing in 1951.

The carrier sits at a depth of 3,000 feet, in a dark, cold, high-pressure environment that Delgado likened to an alien landscape. To put that depth into perspective, Delgado — who was chief scientist on a similar mission to survey the Titanic — noted the Titanic’s final resting place is 12,453 feet below the surface.

But Independence is still deep enough that the 1,500 pounds-per-square-inch water pressure makes its grave inhospitable to human life, Delgado said, explaining the average safe depth for recreational diving is about 100 feet.

While the 60-mile round-trip and detailed survey was completed Tuesday, Delgado said new images of Independence would not be ready for release prior to April. Seeing those images could be an emotional experience for the men who served aboard the ship, Delgado noted. “Indy was home to 1,400 people at any given time,” Delgado said. “She’s been down there 64 years, yet the guys who served on her have never forgotten.”

Documenting the condition and position of the historically significant Independence was just one purpose of the mission, Delgado said, noting his organization also needed to learn how well three systems interacted with each other. The first component was the Boeing-built, 10,000-pound Echo Ranger itself. The second was the AUV’s on-board sonar imaging system designed by Coda Octopus, and the third was the Fulmar and its crew.

Traditionally, these kinds of surveys are conducted using ship-based sonar systems, Delgado said, and that necessitates using large ships that can cost as much as $100,000 per day to operate. However, placing the sonar equipment in an underwater drone such as Echo Ranger makes it possible to use a much smaller vessel, such as the Fulmar, whose operation costs just $5,000 per day, Delgado noted.

Delgado praised the staff of Pillar Point Harbor, saying their support played a big role in having the mission run smoothly.

Harbor Commission President Sabrina Brennan noted that a lot of the curious onlookers who enjoyed Echo Ranger’s visit were seafood aficionados who came to Pillar Point to buy fresh fish directly from local fishermen.

“We’re thrilled to have NOAA and Boeing at Pillar Point Harbor,” Brennan said, “It’s been real fun for visitors to come see the sub and get their questions answered.”

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