April 13, 2021 – Norfolk Naval Shipyard (NNSY) recently teamed with Naval Surface Warfare Center Philadelphia Division (NSWCPD) to bring an advanced prototype to America’s Shipyard with the intent of testing the bond between a coating and hull of Virginia-Class (VACL) Submarines.
The prototype, known as the Hammer Activated Measurement System for Testing and Evaluating Rubber, or HAMSTER for short, was jointly produced by NSWCPD and a contractor to provide a more efficient and accurate reading to determine the bonding condition of the hull of the vessel.
“In the past, shipyard workers would utilize a variety of methods to identify the Special Hull Treatment (SHT) on the vessels; however, these methods were all subjective and opened themselves up to errors in their readings due to the user relying on vibrations or hearing an audible response to determine the quality of the bond,” said NSWCPD Materials Engineer Lisa Weiser, who along with NSWCPD Mechanical Engineer James McDonnell is leading in the prototype’s development and distribution. “The HAMSTER will quickly and objectively identify debonded SHT on Virginia-Class Submarines, using an impact hammer to determine the bonding condition of the hull.”
The HAMSTER is a portable, battery-powered hammer that uses a unique algorithm to provide a real-time evaluation of the condition of the bond with each impact of the hammerhead. Once the worker lightly taps the area with the hammer, lights on the hammerhead will provide a “go, no-go” response, lighting up solid blue to say if the impacted area is good to go or solid red if the area in question is not.
“The HAMSTER has had validation testing performed on in-service submarines with 100 percent accuracy,” said Weiser. “With this, our shipyards are able to accurately identify the SHT and completely repair or replace whatever requires it during maintenance availabilities, ensuring the system is fully operational prior to deployment.”
Following its production, when NSWCPD extended an invitation to the four public shipyards to utilize the prototype, NNSY stepped to the plate in the hopes of performing a full hull inspection on vessels in dry dock.
“There is no reliable technique or tool available to shipyards for identifying SHT debonds,” said NNSY Technology and Innovation (T&I) Lab Representative Dixie Cox. “Current methods utilized are cumbersome or operator dependent. As of now, VACL SHT inspections are primarily visual and various tools are used to tap test the suspected areas to try and determine the extent of debond. This method is very subjective and can lead to excessive work either removing good material or leaving behind debonded SHT without visual indications of failure. NSWCPD has developed an electronic device that will effectively determine debonding on VACL submarines. NNSY can use pierside during upkeeps on USS New Hampshire (SSN 778) and USS New Mexico (SSN 779).”
The mechanics were able to utilize the HAMSTER, training with the prototype and then putting it to use on a submarine.
“For previous jobs we would use a rubber mallet to try and locate spots on the hull that have debonded. We would rely on sound or vibration to locate these areas and when on the project it can be difficult with everything else going on to get the accuracy you want on those readings,” said Woodcrafter Shop (Shop 64) Woodcrafter Robert Penland. “With the HAMSTER, we’ve seen it provide more clarity and accuracy regarding what are the exact spots of debonding firsthand. Once you have a feel for the prototype, it’s easy to use and all-around a great addition to the arsenal.”
The NNSY T&I Lab is excited to bring new technologies to the waterfront, providing the tools needed for the shipyard employees to work more efficiently and safely. “We look forward to assisting in getting test data from HAMSTER users to help further the development of the project,” said Cox. “We’ll continue to work to bring technology and innovations to America’s Shipyard that help our employees succeed.”