A wire or hemp rope, or pendant, secured firmly between two points and used as a support. When refuelling at sea, the oil hosepipe is suspended on a jackstay between the tanker and the ship being refuelled. When an awning is spread over a deck in hot weather as protection from the sun, it is supported centrally on a jackstay, though it is often called a ridge-rope. Also, when a breeches buoy was employed in lifesaving, a jackstay was rigged between ship and shore along which the buoy was hauled to and from the ship. A jackstay, or jackline, is also the name for a line, wire, or length of webbing secured on the deck of a yacht so that those working on deck in heavy weather can hook their safety harnesses onto it to prevent being swept overboard.
Jackstays are rigged with a minimum safety factor of four, i.e. the load supported by a jackstay including its own weight should not be more than one-quarter the breaking strain of the wire or rope used.
Subjects: Maritime History.