The ferry flat would be the transporting vessel (flat bottomed, perhaps similar to a barge).
"Cunue" could be a another spelling (or misspelling) of the word "canoe." (This is just conjecture on my part, but maybe the Cunue was a separate boat in the event that the ferry flat became disabled on the water?)
For paragraph 2, the word "Ferry" could mean: (1) the location where the ferry boat is docked or place of embarkation, (2) the ferry business, or (3) the boat.