Two kayakers adrift in Jamaica Bay with just one paddle unwittingly breached Kennedy Airport’s $300 million perimeter detection system.

They could have been spotted by a boat patrol — except there wasn’t one. Port Authority boats don’t patrol the bay at night, police sources said.

Jordan Crooms of Rosedale, Queens, and Anthony Giglio of Inwood, LI, set out at 11:30 p.m. Friday from a park in Inwood, across the bay from the airport.

“We were just kayaking at night,” Crooms explained.

The duo lost two paddles when their three-man kayak rolled over.

“We had one paddle left,” Crooms said. “We were going toward the closest spot to shore.”

They washed up on a swampy area that juts out from the end of Kennedy’s Runway 4L, said Port Authority police sources. The airport’s perimeter detection system failed to detect the pair, the sources said.

Workers maintaining runway safety equipment found the men at 1:40 a.m. Saturday and turned them over to cops.

Crooms and Giglio, both 21, got summonses for trespassing and were released.

Port Authority boat patrols around Kennedy and La Guardia airports were canceled last year to save money, although some patrols resumed last month after a boat crashed into runway approach lights at LaGuardia when its captain abandoned the helm to participate in a three-way sex romp, sources said. Nighttime patrols around Kennedy have yet to be restored, police sources said.

“Once again a perimeter security breach at JFK Airport raises serious concerns about the Port Authority’s Perimeter Intrusion Detection System, a system the PAPBA believes is a failure,” said a spokesman for the Port Authority police union. “The PA has the vessels, purchased with federal funds, and Coast Guard certified marine police officers to perform a 24-hour marine perimeter patrol with rescue capability.’