Students attend the Harbor School's 2012 graduation ceremony on Governor's Island.

Michael Duffy‘s nascent plans to open a charter school on Governor’s Island have already hit one snag: parent opposition from the nearby Urban Assembly Harbor School, the only school on the island.

Most school space-sharing showdowns begin with worries about cramped buildings and constraints on cafeteria and gym use. But the main concerns held by the parents opposing Duffy’s proposal for the Great Oaks Charter School are the possible cultural differences that could arrise if the grades 6 through 12 school is approved to open in the building next door.

The Harbor school is a marine science-themed Career and Technical Education High School with a state-of-the-art building and a $4 million technology center built with public and private donations. It moved to Governor’s Island in 2010, after years in Bushwick, to have better access to the harbor, where various maritime classes and events are held.

The move was costly, requiring millions of dollars from the city and private fundraising from the Harbor School’s founders to renovate an unused island building. But the school became one emblem of the city’s efforts to breathe new life into the island. It also raised the possibility of new space for the popular but crowded District 2.

Duffy, who formerly oversaw the city’s charter schools office, saw an opportunity to follow the Harbor School’s lead. He also thought the location, with the Statue of Liberty in view, would lend symbolic weight to the school’s aim to have an enrollment of at least 25 percent ELL students, who would have seats reserved in the admissions lottery.

City charter schools have long faced heat for enrolling fewer high-needs students than neighboring district schools, particularly ELL students. But in recent years some are revising their charters to privilege ELLs in their admissions lotteries. Duffy expected most applicants would come from the section of Manhattan below Canal Street, and many ELLs would come from Chinatown.

“We aim to be a place where students from families of every economic status will feel comfortable,” Duffy’s charter application says. The school would be “fittingly in view of the Statue of Liberty as we recruit students from among those families who have recently immigrated to America.”

Great Oaks would be modelled off the college preparatory school MATCH in Boston, of which Duffy was a founding board member. It would share its name and college readiness focus with a MATCH-inspired school in Newark, which Duffy also helped to found last year.

One of the hallmarks of the MATCH model is its tutoring program, which offers struggling students hours of one-on-one tutoring with teachers in training. Tutors at Great Oaks would have the option to take subsidized classes at New York University’s Steinhardt School of Education, and earn a teaching certification after a year.

Duffy said his plan from the start has been to create new seats in the crowded District 2, where co-location battles are tense, by seeking private space. The vacant site on Governor’s Island was a more affordable option than to search for private space in dense Lower Manhattan, and it had the added appeal of creating an opportunity to further the city’s ongoing efforts to restore Governor’s Island.

But when Duffy met with parents from the Harbor School at a community meeting in June, Parent-Teacher Association president May Taliaferrow and others raised concerns about the proximity of two schools with different visions. She was not available to comment today.

“I think it becomes a huge distraction for the founding teams to be engaged in that fight, and I’d be much more interested in working on building our programs,” Duffy said in an interview. “We wanted to be a solution, rather than slice up an already thin pie. Governor’s Island is a place that the [Bloomberg] administration is investing a lot of resources in to kind of bring it to life.”

Taliaferrow, a vocal charter school critic for several years, is now circulating a petition criticizing the charter school for lacking the Harbor School’s curricular emphasis on “environmental stewardship,” calling it “a foreseeable cultural conflict.” She also put out a call over email to parents this morning asking them to attend the charter school’s proposal hearing on August 30.

The charter school hearing could be the first road bump of many to come for Great Oaks. If it is approved, Duffy would need to raise the funds to renovate the vacant building adjacent to the Harbor School—a capital project that could cost $40 million or more. Duffy, who has led capital fundraising projects for other charter schools in Boston, said he is not daunted by the cost, which he plans to raise through a combination of historic tax credits, private donations, and debt financing.