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News | May 12, 2021

NSWC Carderock inventors patent Device for Non-Lethal Stoppage of Water Jet Propelled Craft

By Todd Hurley, NSWCCD Public Affairs

The patent, U.S. Patent 10,323,911 B1, Device for Non-Lethal Stoppage of Water Jet Propelled Craft, was introduced during Naval Surface Warfare Center Carderock Division’s (NSWCCD) first Engineers Week event, held in February. It was granted to the six NSWCCD co-inventors on June 18, 2019, though it was submitted in 2016.

“My role with patents is dual-hatted — I’m the Maritime Systems Hydromechanics Branch head and the Naval Architecture and Engineering Department representative on the Invention Evaluation Board,” Bretall said. “This idea came about for a project that was in collaboration between Carderock personnel at West Bethesda and the Combatant Craft Division. Like a lot of people at Carderock, we were trying to solve a very unique problem — something that on the surface might not seem like that big of a deal, but actually once you dig into it, it becomes very complex.”

The problem they tried solving was how to stop a personal watercraft, such as a Jet Ski, in a non-lethal manner.

“There’s a lot of reasons you might want to stop one — it could be something that could be headed toward a naval asset, they could be drug-running and could be getting away,” Bretall said. “The simplest conventional way, of course, is to use kinetics and artillery, but that’s only appropriate in some situations … there’s a lot of reasons you might want to stop a Jet Ski non-lethally.”

The engineering goals of the device were for it to be non-lethal to the watercraft operator, to minimize irreversible damage to the vessel, and to be removable without having to lift the vessel out of the water. The device had to degrade in the water over time and be quickly deployable from a safe distance.

Other engineering goals included being heavy enough to launch, stable enough to fly straight, neutrally buoyant, long enough to reach the waterjet inlets, soft enough to not suddenly stop the impellers or damage the blades, flexible and malleable enough to fit through grate openings, and tacky enough to stay on the impeller blades and block flow or occlude generated thrust.

The biggest challenge the inventors faced was figuring out how to get their device from a ship or boat into the impeller.

The solution was essentially a standard, off-the-shelf, t-shirt cannon that shoots out the device. The device has a weighted head and tentacles that float to the surface, which will ideally get stuck in the shaft of the vehicle, causing it to lose propulsion. After various model-scale tests at the David Taylor Model Basin, the full-scale testing took place at the Oil and Hazardous Materials Simulated Environmental Test Tank outdoor basin in New Jersey.

“What we came up with meets most of the engineering goals,” Bretall said. “A lot of Carderock inventors initially think, ‘Ah, this is so obvious, I can’t believe someone hadn’t come up with this,’ but, you have to remember, you are sometimes addressing a problem that no one in the world has ever needed to address. Even if it’s something that might be obvious to you, it’s definitely worth seeing if it’s been done and patented.”

Bretall and the other inventors are currently trying to figure out a home for their device.

“The future for the device is still unclear,” Bretall said. “Some things you get a patent for end up getting a lot of attention, and others don’t. We’ll have to wait and see what comes of this one.”

In addition to Bretall, the patent was co-invented by five other individuals, four of whom are still at NSWCCD. Andrew Krauss, Mechanical engineer, Maritime Systems Hydromechanics Branch was the lead on the invention. Alma Jacobson, Branch head, Research and Development Systems Engineering Branch; Steve Brandis, technician, Naval Architecture and Engineering Department; Ryan Faber, Naval architect, Test and Evaluation Engineering Resource Branch; and Chelsea Shores, a previous Carderock employee.