Ships approaching and preparing to anchor near underwater electric cables in Hempstead Harbor and Long Island Sound will receive electronic alerts from a new virtual smart-buoy system designed to prevent damage to the state-owned power lines.

The New York Power Authority, working with electronic navigation firm Vesper Marine, is activating the new virtual protective-zone system this week, the first of its kind in the nation, NYPA said.

The system uses existing satellite-based electronic navigation technology to monitor and communicate with ships in the vicinity of the cables, and automatically send increasingly urgent alerts if the ships appear to be preparing to drop anchor. The Federal Communications Commission and the U.S. Coast Guard have issued approvals.

The system, which covers 7.5 miles of the 26-mile cable, is designed to prevent mishaps such as the anchor strike that damaged one of the four cable lines between Long Island and New Rochelle in January 2014. A barge dropped anchor in Hempstead Harbor and damaged a small section of the 600 megawatt line, which allowed 66,000 gallons of nontoxic cable insulator fluid to leak.

It cost about $35 million to repair the cable, and NYPA is in litigation to recoup the amount from the Melville-based shipping company. The line was previously damaged in 2004.

The Long Island Sound Y-49 line, a system of four cables, currently is out of service because of a land-based problem near the East Garden City substation, but is expected to be back online this week, NYPA said.

The new protective zone uses an automatic identification system to alert ships to their proximity to the cables using new electronic buoys at eight points in the waterway along with equipment that all larger ships carry for navigation.

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“Any boat that has AIS warning systems would get the alerts,” said Jeff Robbins, chief executive of Vesper Marine of Auckland, New Zealand.

The system will keep a list of “trusted” vessels that use the harbor frequently and don’t set anchor and thus will not get alerts. The system can be used by sailboats and smaller pleasure boats that use the harbor; they will be able to use the new eight-buoy system to navigate when visibility is low.

In a demonstration of the system in Hempstead Harbor last Wednesday, the system posted an alert on navigation equipment saying, “Cable field. Do not enter,” as a boat approached the cables. When the boat slowed to a stop, as if it were preparing to set anchor, the system sent an alert saying, “Cable field. Do not anchor.” The system can also send audio, text and email alerts to vessels in the field.

NYPA can monitor the system and activity around the line from its White Plains headquarters.

The four cables in the Y-49 Long Island Sound cable are as much as 600 feet apart and buried 10 feet under the sea bed at the deepest part of the harbor, said Robert Schwabe, director of asset and maintenance management for NYPA. The agency will pay about $75,000 to establish the system of virtual beacons and pay for equipment, then pay an annual cost to Vesper Marine to operate it.

“We’re trying to do the best we can to be proactive to be sure we don’t have any future strikes,” Schwabe said. “It’s an environmental and safety issue.”