The U.S. Navy protects its surface ships and submarines from underwater magnetic influence mines through a two-step process consisting of magnetic treatment followed by degaussing system calibration, typically at the beginning of the ship or boat’s service life. USNS John Lewis (T-AO 205) underwent treatment and calibration at Naval Base Point Loma in San Diego in March. Personnel from Naval Surface Warfare Center (NSWC), Carderock Division and NSWC Philadelphia Division, Naval Undersea Warfare Center, Division Keyport’s San Diego Detachment, as well as Naval Sea Systems Command (NAVSEA) were involved in the trial. Carderock served as the In-Service Engineering Agent for the degaussing system that was being calibrated. The purpose of the trial was to minimize the ship’s susceptibility to underwater mines.

Carderock employees Marella Camello, a technical program manager with the Program Management Branch, and William Gay, the technical lead with the Underwater Electromagnetic Signature Control, Analysis and Susceptibility Branch, worked on the trial.

“It was a two-part trial, the first part was the magnetic treatment, the second part was the calibration of the advanced degaussing system for magnetic signature control,” Gay said.

According to Gay, the process of magnetic treatment changes a ship or boat’s magnetic signature by removing construction-related magnetic irregularities and stabilizing the signature to prevent future changes throughout the service life of the ship or boat. Treatment also ensures the degaussing system can best perform its job of cancelling the ship’s signature more effectively, by smoothing out the signature and putting it in a state the degaussing system was designed to mask. Treatment ensures the degaussing settings established during the degaussing system calibration are valid for a longer period of time due to the signature being stable.

Camello served as the technical program manager for the planning and coordination leading up to the trial. Beforehand, she determined the personnel needed to support the trial, as well as the funding to complete the trial. Gay had several roles for the entire program. Before the trial, Gay was a mentor for Camello and helped develop the test plan used for the calibration. During the trial, his job was to analyze signature data as it was acquired and adjust the degaussing system settings to minimize the ship’s magnetic signature. After the calibration, he will perform any necessary post-trial analyses and write a report documenting all efforts of the trial team.

Developing the test plan was actually a straightforward process according to Gay.

“This trial is very similar to many previous ones, giving us the advantage of being able to leverage prior test plans,” he said. “We came up with a prior test plan and added whatever nuance we needed for this ship, which was first in class.”

Even though the test plan was straightforward, the calibration itself posed several challenges for both Camello and Gay. Weather delayed calibration for a couple of days. For Camello, she recently became a technical program manager and was learning on the job.

“This was my first trial as a program manager,” she said. “I am still learning how to run trials, who to talk to and balancing my time with everything else that’s in my portfolio that I have to manage.”

Gay noted other challenges. There was the challenge of establishing hardware communications and debugging degaussing system components, a common aspect of all such trials. In addition to preparing the ship for the calibration, there was also duration of the calibration efforts itself. The trial took place in San Diego, a long time away from families and friends. Normally, these were not long engagements, but John Lewis was a first-in-class trial, requiring additional measurements.

“As this was a first in class, it is never a cakewalk,” he said. “We have a pretty good idea of what we think the signature is going to look like both before and after the ship is magnetically treated. However, there is a lot of stuff you’re finding out for the first time with a new ship class. Additionally, this is a time critical process, especially toward the end because time is short and we’re trying to finalize the calibration.”

High intensity and long duration degaussing system calibration trials requiring Carderock involvement are not performed for legacy ships – ships with degaussing systems dating back to the 1980s with capabilities and technology from that era. Treatment and calibration of legacy ships is straightforward and is performed by local magnetic silencing personnel. Advanced Degaussing ships such as USNS John Lewis, equipped with complex and highly capable degaussing systems intended to defeat the modern mine threat, do require a more involved calibration process and Carderock’s magnetic signature control expertise and assistance.

“Since the end of the second World War, we lost more ships to naval mines than any other threat there is – missiles, terrorist attacks or anything,” Gay said. “Mines are really a nightmare for the Navy. They’re very asymmetrical form of warfare since they are cheap relative to the cost of a naval warship. They are simple devices with an explosive charge and a little bit of logic attached. You can throw those overboard and they go to the bottom and just wait until a ship comes along. The degaussing system minimizes the ship’s signature and makes it a lot harder for mines to detect the ship and attack it.”