Source : Webster's Revised Unabridged Dictionary (1913)

Weatherliness \Weath"er*li*ness\, n. (Naut.)
   The quality of being weatherly.

Source : WordNet®

weatherliness
     n : (of a sailing vessel) the quality of being able to sail
         close to the wind with little drift to the leeward (even
         in a stiff wind); "the Spanish ships had superior speed
         and weatherliness"