Time is a major factor in any contingency operation, especially when it comes to securing ports in order to transport personnel, supplies and equipment. When a pier or marine structure is damaged, it can cause catastrophic delays. In some cases, repairing these structures can be dangerous work for U.S. Army and U.S. Navy dive teams as the surrounding environment may be hostile or extremely hazardous.
A team of researchers from the U.S. Army Engineer Research and Development Center’s Coastal and Hydraulics Laboratory, led by principal investigator Thad Pratt and including co-pi William Butler and research engineers Jonathan Marshall and David Nguyen, have developed and improved a prototype Multifunctional Assessment Reconnaissance Vessel that allows for remote survey of pile-supported marine structures. Operators can produce final data products within 12 hours of arriving on site, allowing structural engineers to deliver a repair plan within 24 hours. The U.S. Transportation Command and Office of the Secretary of Defense-funded project has resulted in the schedule of five units to be delivered to Army dive detachments as part of the Instrument Set, Reconnaissance and Surveying (ENFIRE) program.
“The one we have now is our prototype, and it is going to stay here with CHL,” said Marshall. “But we’re building five more units that are all going to go to the Army. Those units will go to the Army dive teams, and they can assist them in their regular work.”
The MARV and MARV II can perform the same functions, as most full-size survey boats with all of the same instrumentation and technology available to the user. The first MARV concept was a modified commercial off-the-shelf vessel that was successful in proving the idea could work, but needed improvement. After much evaluation and testing, it was determined a new platform was needed. CHL researchers found the design they were looking for at Marine Advanced Robotics and enlisted their help reducing the size of the company’s current vessel that accommodated the needs of Army divers.
“We found a design of a vessel we really liked and contacted the company and got them to scale it down to a size that fit what we were doing,” said Marshall. “They normally make boats that are 16 feet and more, and we had them more or less cut that in half.”
The MARV II has a redesigned platform that includes increased stability, upgraded sensors, autonomous navigation and is approximately nine feet in length when assembled. The vessel is easily transportable and rapidly deployable, with components designed to be broken down and stowed in commercial air travel cases, allowing for a smaller footprint when stored. It also has the ability to be launched from land or lowered into the water and can operate in as little as six inches of water.
While the vessel operation software is a commercially licensed product, the data collection and organizing software was developed at CHL by Research Physical Scientist Naveen Ganesh.
Marshall said the hardest part was figuring out how to combine collected and organized data into a process that can be easily transferred to a structural engineer for assessment. “These guys are collecting a lot of information that normally a hydrographic surveyor collects and processes, and then takes a week or so to generate a final product,” said Marshall.
The software program, called the Pier Diagram Tool, creates a three-dimensional diagram of the entire structure, including every pile and piece of damage within hours. The structural engineer then points and clicks on the model to get a full representation of the structure including videos, pictures and screen shots of data.
CHL researchers have been working with Army dive teams in New Jersey and Virginia to train members on the MARV II. With just two weeks of instruction, divers are able to assemble and pilot the vessel, draw a diagram of the damaged structure, and extract sonar and LIDAR data from the watercraft and place it into the model for a complete assessment to hand over to the engineer.
“We are actually training the divers every time we have an event,” said Marshall. “We’re training them to use the system. We start with taking everything out of cases and putting it all together. We give them step-by-step instructions. It’s been going pretty well, we’re getting a lot of feedback and improving it every time.”
Although the MARV II is still in the prototype phase, it’s already building interest. CHL researches recently participated in an exercise for the USTRANSCOM-funded, CHL-designed mini-robotic submersible dredge, with the MARV II performing the survey portion of the exercise. The Navy is also interested in using the vessel for port inspections.
Story was originally published on Page 129 of the 2020 Edition of the “U.S. Army Corps of Engineers Building Strong®: Serving the Nation and the Armed Forces” Faircount Media Group publication. It may also be found at <https://usacebuildingstrong.com/>.