Private noncommercial marinas designed for the mooring, launching and fueling of pleasure craft, provided that dry storage and boat maintenance facilities do not exceed twenty-five feet in height. Minimum lot requirements shall be: lot area, twenty thousand square feet; lot width, one hundred feet; front yard setback, thirty-five feet [see § ZS 1-305(b) hereof]; each side yard setback, thirty feet; and rear yard setback, thirty feet; provided, however, that any such marina, boat storage, launching or maintenance facility must be incidental to a principal permitted use or structure, group of uses or group of structures and located on the same or on a contiguous lot or tract of land. Such marina, boat storage, launching or maintenance facility may serve a single lot or group of lots, provided that it is contiguous to one or more of such lots or a common area contiguous to and serving the lots. Any marina, boat storage, launching or maintenance facility may not provide for the docking, storage or maintenance of more than one boat per lot or per dwelling unit. The Board of Zoning Appeals may grant a waiver of the requirement of contiguousness, but in no event shall the marina, boat storage, launching or maintenance facility be permitted more than two hundred feet from the lot or from one of the lots served.