In Watz v. Zapata Off-Shore Co., Judge Wisdom presents a well-articulated discussion pointed directly at the unsettled issue of when a ship is "in navigation". The significance of the court's determination is that the question of fact presented in this case is a close one, emphasizing an area never thoroughly considered by the Supreme Court; an area in need of further illumination.
John M. Gantus,
Warranty of Seaworthiness--A Non-Seaman's Dilemma,
San Diego L. Rev.
Available at: https://digital.sandiego.edu/sdlr/vol8/iss3/13