P's dock was struck by D's barge, driven by its tug, in the early morning hours of July 4, 1979. At some point prior to the accident a socket, making the starboard wire rope that secured the tug and barge, failed. The socket was manufactured by American Hoist (D). P sued D and American Hoist (D). The latter two cross-claimed against each other. The judge awarded P its damages against D, absolved American Hoist (D) of liability, and awarded American Hoist (D) its expenses from P. D appealed.