Researchers in Texas say they've successfully "spoofed" a GPS signal in a test that resulted in a 213-foot yacht at sea getting coerced off its course.

The radio navigation research team from The University of Texas at Austin said they successfully spoofed the $80 million private yacht using the world's first openly acknowledged GPS spoofing device.

The purpose of the experiment was to measure the difficulty of carrying out a spoofing attack at sea and to determine how easily sensors in the ship's command room could identify the threat, a university release said Wednesday.

The demonstration was intended to highlight the perils of navigation attacks and show spoofing is a serious threat to marine vessels and other forms of transportation, the researchers said.

"With 90 percent of the world's freight moving across the seas and a great deal of the world's human transportation going across the skies, we have to gain a better understanding of the broader implications of GPS spoofing," engineering Professor Todd Humphreys said. "I didn't know, until we performed this experiment, just how possible it is to spoof a marine vessel and how difficult it is to detect this attack."

The team was invited aboard the yacht White Rose of Drachs in June, as it traveled from Monaco to Rhodes, Greece, on the Mediterranean Sea.

The experiment took place about 30 miles off the coast of Italy as the yacht sailed in international waters.

The researchers broadcast civil GPS signals from their spoofing device -- a blue box about the size of a briefcase -- toward the ship's two GPS antennas, eventually overpowering the authentic GPS signals and gaining control of the ship's navigation system.

The team's false signals were indistinguishable from authentic signals to the ship's GPS devices, allowing the spoofing attack to happen covertly and cause the ship to turn while instruments on the bridge indicated it was still traveling on its intended course, the researchers said.

"The surprising ease with which Todd and his team were able to control a (multimillion) dollar yacht is evidence that we must invest much more in securing our transportation systems against potential spoofing," Chandra Bhat, director of the university's Center for Transportation Research, said.