The Collaborative International Dictionary of English v.0.48:

Seamanship \Sea"man*ship\, n.
   The skill of a good seaman; the art, or skill in the art, of
   working a ship.
   [1913 Webster]

WordNet (r) 3.0 (2006):

seamanship
    n 1: skill in sailing

Moby Thesaurus II by Grady Ward, 1.0:

67 Moby Thesaurus words for "seamanship":
   ability, address, adeptness, adroitness, airmanship, artfulness,
   artisanship, artistry, bravura, brilliance, capability, capacity,
   cleverness, command, competence, control, coordination, craft,
   craftsmanship, cunning, deftness, dexterity, dexterousness,
   dextrousness, diplomacy, efficiency, expertise, facility, finesse,
   grace, grip, handiness, horsemanship, ingeniousness, ingenuity,
   know-how, marksmanship, mastership, mastery, practical ability,
   proficiency, prowess, quickness, readiness, resource,
   resourcefulness, savoir-faire, savvy, sea legs, seamanlikeness,
   seamanliness, shipmanship, skill, skillfulness, style, tact,
   tactfulness, technical brilliance, technical mastery,
   technical skill, technique, timing, virtuosity, weather eye, wit,
   wizardry, workmanship