Standing rigging comprises the fixed lines, wires, or rods, which support each mast or bowsprit on a sailing vessel and reinforce those spars against wind loads transferred from the sails. This term is used in contrast to running rigging, which represents the moveable elements of rigging which adjust the position and shape of the sails. Historical development Early sailing vessels used rope of hemp or other fibers, which gave way to wire ropes of various types. Galvanized steel was common for the first half of the 20th century, continuing as an inexpensive option to its 1960s successor material—stainless steel cables and rods. In the late 20th Century, racing yachts adopted composite fiber lines for standing rigging, with the goal of reducing weight and windage aloft. Materials On modern yachts, standing rigging is often stainless steel wire, Nitronic-50 stainless steel rod or synthetic fiber. Semi-rigid stainless steel wire is by far the most common as it combines extreme strength, relative ease of assembling and rigging with reliability. Unlike rigid stainless steel rod, it is comparatively easy to recognize wear and stress as individual strands (normally 19) break often near a swage fitting, and can be inspected while standing. Solid rod stainless steel is more aerodynamic so is often used in extreme racing yachts but it is difficult to see stress as this requires professional inspection such as dye penetrate testing or x-raying. Rod rigging is strongest when terminated with a cold head rather than swage fittings. This process requires a different, expensive machine but yields a more durable end fitting. Rod-type stays fail suddenly (rather than strand by strand as a cable would), often where the rod bends around a spreader. Bending can induce unseen stress fractures. Fore-and-aft rigged vessels Most fore-and-aft rigged vessels have the following types of standing rigging: a forestay, a backstay, and upper and lower shrouds (side stays). Less common rigging configurations are diamond stays and jumpers. Both of these are used to keep a thin mast in column especially under the load of a large down wind sail or in strong wind. Rigging parts include swageless terminals, swage terminals, shackle toggle terminals and fail-safe wire rigging insulators. Square-rigged vessels Whereas 20th-century square-rigged vessels were constructed of steel with steel standing rigging, prior vessels used wood masts with hemp-fiber standing rigging. As rigs became taller by the end of the 19th century, masts relied more heavily on