For adding boats, you need to set the boat's UPC and cfg files (Roster and Submarine folders) to match your target dates, as well as any equipment you might need on the boat (if it isn't already set that way). Add or alter the dates of the boat in the Flotilla.upc file, and add the boat's listing to the CareerStart.upc file, both found in the Data / UPCData / UPCCampaignData folder (unless a U-Boat, and you would use UPCDataGE). It just looks confusing...
[famous last words before the CTD]
