The marina expansion is the first step in a 10-acre redevelopment of the former Portland Co. property. Artist's rendering by Perkins+Will of Boston A Portland developer is soliciting public bids for a marina expansion tied to an ambitious redevelopment of Portland’s eastern waterfront. The marina expansion will more than double the number of boat slips at the current 58 Fore Street marina and make space for “mega yachts.” Expanding the marina is the first step in a 10-acre redevelopment of the former Portland Co.