Updated 10:25 a.m. April 12

With clouds overhead in the salty air, irritable Pacific waves swelled to up to four feet. Perfect conditions, in other words, for the Navy to fry a small boat with a laser beam — a major step toward its futuristic arsenal of ray guns.

Researchers mounted the Maritime Laser Demonstrator, a solid-state laser, aboard the USS Paul Foster, a decommissioned destroyer. Off the central California coast near San Nicholas Island on Wednesday, the laser fired a 15-kilowatt beam at an inflatable motorboat a mile away as both ships moved through the sea. As the above video shows, there was a flash on the boat’s outboard engines, igniting both of them in seconds, and leaving the ship dead in the choppy waters.

All previous tests of the laser have come on land — steady, steady land — aside from an October test of the targeting systems. But for the first time, the Office of Naval Research has proven that its laser can operate in a “no-kidding maritime environment,” says its proud director, Rear Adm. Nevin Carr.

“I spent my life at sea,” Carr says in an interview with Danger Room, “and I never thought we’d see this kind of progress this quickly, where we’re approaching a decision of when we can put laser weapons on ships.”

Fewer than three years after the Navy awarded Northrop Grumman a contract worth up to $98 million to build the Maritime Laser Demonstrator, it’s proven able to cause “catastrophic failure” on a moving target at sea the first time out, says Quentin Saulter, one of ONR’s top laser gurus.

“When we were doing the shot and the engine went, there was elation in the control room,” he says. “It’s a big step, a proof of principle for directed energy weapons.”

The Navy hopes that by the next decade, solid state lasers — which generate powerful beams of light by running electrons through crystals or glass — will be aboard its surface ships, disabling enemy vessels and eventually burning incoming missiles out of the sky. That latter goal will take at least 100 kilowatts of power.

But a beam in the tens of kilowatts, ONR proved this week, is deadly, accurate and, Carr says, “can be operated in existing power levels and cooling levels on ships today.”

Solid state lasers are just the beginning. The Navy’s also working on a much more powerful Free Electron Laser weapon thanks to ONR’s research. That laser works across multiple wavelengths, compensating for debris in the sea air, to cut through 20 feet of steel per second once it gets up to megawatt class. Its electron injectors are ahead of schedule and ONR expects it to be ready in the 2020s, though after its solid state cousins are operative.

Next up will be to “develop the tactics, the techniques, the procedures and the safety procedures that sailors are going need to develop” to wield laser weapons, Carr says. And then it’s time to scale up the laser’s power.

“This is an important data point,” the admiral says, “but I still want the Megawatt death ray.”

Update: Corrected the strength of the megawatt-class FEL after an earlier miscommunication with the Office of Naval Research.

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