Accessory berths or moorings may be provided on a zoning lot other than the same zoning lot as the residences to which such berths or moorings are accessory, provided that:

(a)        both zoning lots are contiguous or would be contiguous except for their separation by a street or street intersection; and

(b)        both zoning lots are in common ownership (single fee ownership or alternative ownership arrangements of the zoning lot definition in Section 12-10).