The Collaborative International Dictionary of English v.0.48:
Captainship \Cap"tain*ship\, n. 1. The condition, rank, post, or authority of a captain or chief commander. "To take the captainship." --Shak. [1913 Webster] 2. Military skill; as, to show good captainship. [1913 Webster]WordNet (r) 3.0 (2006):
captainship n 1: the post of captain [syn: captainship, captaincy]