Hiya Chuck
As to the goodies like Greavette, Ditchburn, Minette, and so on, may I suggest the antique boat museum in Clayton, NY, Mystic Seaport museum in Mystic, Conn. and the Mariners Museum in Norfolk? These museums have the bulk of available launch plans but be prepared to open your wallet for copies and documentation. You may also wish to join the Antique and Classic Boat Society
You might try Swensons.com and subscribe to Wooden Boat magazine and order their electronic media back issue collection; about $150.
Ebay is another source, as is a search on Google or Altavista for “free modelboat plans”.
Be also prepared to get some downright snotty replies or no replies at all when querying some sources.
I am trying to start a runabout clearing house on yahoogroups called classic-wooden-boat-models but it is in its infancy due mainly to my recurring health problems.
Good Luck!