The Collaborative International Dictionary of English v.0.48:

Keelage \Keel"age\, n. [Cf. F. guillage, fr. guille keel; of
   German or Scand origin. See 3d Keel.]
   The right of demanding a duty or toll for a ship entering a
   port; also, the duty or toll. --Bouvier. Wharton.
   [1913 Webster]