The Rouse Co., developer of Columbia, Md., and a number of successful mixed-use marketplaces across the country, is trying out its formula in Manhattan, where it will help build a $210 million riverfront complex of shops, offices, restaurants and a hotel.

Planned with the flavor of another of its projects, Faneuil Hall marketplace, now a Boston landmark, the South Street Seaport marketplace would blend new structures with historic museums and buildings of Manhattan's east side seaport area. The project is meant to lend a festival atmosphere to the Big Apple's seedy side.

New York Mayor Edward Koeh called the union with Rouse a "beautiful marriage, a marriage of a major economic investment with another of my biggest priorities, the revitalization of New York City's waterfront."

Fish markets, a few restaurants, some "ramshackle buildings," and 160-to-170-year-old historic buildings line the somewhat "seedy and dilapidated" streets of Manhattan's east side, which was a vigorous trade center at the turn of the century, a Rouse spokesman said.

The area is saved however, by state and independently-owned marine museums which will form a centerpiece for the development. The new marketplace won't, however, overwhelm the quaint character of the area, the Rouse spokesman said.

Rouse would spend $60 million on the project with the remainder coming from city, state and federal funds.

The Columbia, Md.-based company would develop small shops and cafes, a pier with more than 100,000 square feet of market space on two floors and a new building behind the existing fish market stalls, the Rouse spokesman said.

An office and hotel complex with more shops, replacing a vacant lot, will be managed by Rouse.

The Manhattan marketplace would be Rouse's 36th project, if it is approved by citizens at a public hearing and then by the city, the spokesman said. Construction is scheduled to begin in 1981 and the end of next year, the spokesman said.

The project, which includes the refurbishing of several 19th century ships, would be situated along Fulton Street between Water and South Streets and on a new 111,000-square-foot pier platform behind the Fulton Fish Market's Tin Building just north of Fulton Street.

The project was started about two years ago when officials of one of the seaport museums asked Rouse if the company could build a showcase for the museum similar to Boston's Faneuil Hall, the Rouse spokesman said: "It looked very feasible to us," the spokesman said.

Boston's market, which has attracted about 12 million shoppers a year since it opened in 1976, has more than 350,000 square feet of small shops housing crafts, jewelry, and clothing stores and cafes in a 19th century marketplace. It is part of a downtown revitalization plan as are similar Rouse projects in Philadelphia and in Baltimore.

The Manhattan project is expected to create 1,700 construction jobs and 800 permanent jobs and $7 million in taxes for the city and state, the Rouse spokesman said.

The company expects to see a profit by the second or third full year of operation, the spokesman said.