The Collaborative International Dictionary of English v.0.48:

Masting \Mast"ing\, n. (Naut.)
   The act or process of putting a mast or masts into a vessel;
   also, the scientific principles which determine the position
   of masts, and the mechanical methods of placing them.
   [1913 Webster]

   Masting house (Naut.), a large building, with suitable
      mechanism overhanging the water, used for stepping and
      unstepping the masts of vessels.
      [1913 Webster]