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Potential Water-Barrier Defense for Riverine Craft Makes a Splash
Photo courtesy Dr. Ray Gamache

Potential Water-Barrier Defense for Riverine Craft Makes a Splash

By Javier Chagoya

In the final months of World War II, as the battle for the Pacific raged on, ship commanders employed out-of-the-box maneuvers to keep torpedoes, bombs, strafing, and even kamikaze aircraft, from hitting their ships. One creative defensive tactic used against approaching aircraft was to train the ship's gun at the water just in front of the plane in an effort to swamp it before it collided with the ship. Now, an NPS professor is revisiting this low-tech defensive tactic with some convincing data.


NPS Department of Physics Professor Raymond Gamache and U.S. Naval Research Laboratory scientist Dr. William Szymczak have developed a model that demonstrates that a burst of water can effectively stop a projectile, such as a rocket-propelled grenade (RPG), aimed at riverine craft.

"We have created a model for directing a splash zone large enough, and with ample density, to mitigate an incoming projectile," said Gamache.

Gamache's concept would use the active infrared radar detection system onboard the riverine craft that can track and defeat incoming threats, including RPGs and missiles. Based on split-second calculations from data via onboard sensors, the craft deploys an explosive charge directed into the water along the calculated flight path of the threat. The charge detonates, creating a water barrier sufficient enough to change the angle of the RPG and/or detonate and absorb the incident threat debris away from the boat's occupants.

"If you can imagine a detonated explosive that creates an upward surge of water 48 inches thick and 15 feet high, with a velocity of 100 to 160 feet per second, it's like putting up a cement wall in the path of that RPG in a time scale of a tenth of a second," described Gamache.

Recently, Gamache presented his paper to attendees of the 2017 Operations and Technology (OPTECH) South Conference held in Cartagena, Colombia. The event was conducted by NPS' own Littoral Operations Center and supported by the Office of Naval Research-Global, the Colombian Naval Science and Technology Office, and Swedish defense company, Saab.

Gamache says the Colombian Navy showed great interest in his theory of combating RPG attacks by employing a force field made of water, and offered a tentative nod to field test his theories in their sovereign waters.

"Small riverine craft can't effectively negotiate their waters with exceedingly high weight deficits associated with steel plating or heavy guns," says Gamache, "So having a suite of small explosive charges that only needs two to three feet of water to foil an attack is a big win in protecting the small craft."

Further testing under both static and moving targets will have to be conducted, Gamache says, adding that he hopes to secure additional funding to forward the idea to field testing.


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May 2017

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