Spectators bound for Thursday’s Democratic presidential debate in Brooklyn will face some presidential-level scrutiny, courtesy of the U.S. Secret Service.

For instance, ticket holders who choose to board special boats in Manhattan bound for the debate venue at the Brooklyn Navy Yard will be scrutinized by the Secret Service before the 12-minute ride. And, after the ferries dock, the screenings will be repeated all over again.

Checking everyone bound for the yard’s Duggal Greenhouse is one of the ways the authorities are seeking to prevent trouble — precautions based on long-established best practices and on-site scouting done jointly by the Secret Service and NYPD.

In addition to firearms and other weapons, the Secret Service will be helping keep out items that organizers say could disrupt the debate, such as campaign signs, political stickers, noisemakers, clothing that lights up and protest placards.

The NYPD’s Strategic Response Group — a heavily-armed quick-reaction force created early last year to handle calamities like terrorist attacks — “can be activated within minutes” in case the force is needed at the debate, said the NYPD’s chief spokesman, Stephen Davis.

Authorities, led by the NYPD, also will police a so-called “free-speech zone,” where protesters or supporters can gather outside the debate hall, said Michael Seremetis, assistant special agent in charge of the Secret Service in Brooklyn. His office is coordinating debate security with the help of counterparts from the agency’s headquarters in Washington, D.C.

“We’re prepared at any site for whatever you can imagine,” said Seremetis, who detailed some of the security plans in an interview.

There won’t be parking available at the yard, and organizers hope spectators will choose to ride shuttles — either the boats available near 35th and 34th streets and the FDR Drive in Manhattan, or buses from the nearby York Street F train stop in Brooklyn.

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Attendees being dropped off by cars or taxicab must walk several blocks to the venue, Seremetis said.

Natalie Grybauskas, a spokeswoman for New York City Mayor Bill de Blasio, said while city officials expect more traffic on the area’s roadways, overall there should be a minimal impact.

Located at the borough’s northern tip, the Brooklyn Navy Yard was decommissioned from military use in 1966. The land is now owned by the city and serves as an industrial park.

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Officials there expect the debate to provide little disruption to the yard’s regular functions and the 330-plus businesses located there, said the yard’s spokesman, Jerome White.

“Businesses are operating. People are coming, people are going,” White said. “Life goes on.”