The industrial zone along the waterfront in Sunset Park is a remnant of when the area was filled with cold storage warehouses, major international shipping operations, and heavy industry that ranged from canneries to ammunition factories. The blocks between Third and Fourth Avenue, just east of the Gowanus Expressway, have always felt a little more transitional, because they mix low-slung warehouses with little prewar townhouses. But the neighborhood’s zoning prevents new residential construction, and all the new buildings that sprout here are budget hotels. One such hotel is in the works at 142 33rd Street, across the street from two more newly finished hotels.