1911 Encyclopædia Britannica/Rudder

RUDDER (O.E. Rother, i.e. rower), that part of the steering apparatus of a ship which is fastened to the stern outside, and on which the water acts directly. The word may be found to be used as if it were synonymous with "helm." But the helm (A.S. Hillf, a handle) is the handle by which the rudder is worked. The tiller, which is perhaps derived from a provincial English name for the handle of a spade, has the same meaning as the helm. In the earliest times a single oar, at the stern, was used to row the vessel round. In later times oars with large blades were fixed on the sides near the stern. In Greek and Roman vessels two sets were sometimes employed, so that if the pitching of the ship lifted the after pair out of the water, the foremost pair could still act. As these ancient ships were, at least in some cases, sharp at both ends and could sail either way, steer (or steering) oars were fixed both fore and aft. The steer oar in this form passed through a ring on the side and was supported on a crutch, and was turned by a helm, or tiller. Norse and medieval vessels had, as far as we can judge, one steer oar only placed on the right side near the stern—hence the name "starboard," i.e. steerside, for the right side of the ship looking forward. In the case of small vessels the steer oar possesses an advantage over the rudder, for it can bring the stern round quickly. Therefore it is still used in whaling boats and rowing boats which have to work against wind and tide, and in surf when the rudder will not act. It is not possible to assign any date for the displacement of the side rudder by the stern rudder. They were certainly used together, and the second displaced the first in the course of the 14th century when experience had shown that the rudder was more effective at the stern than at the side. The rudder of a wooden ship when fully developed was composed of four pieces. The first or main piece was hung on to the stern post of the ship. Its upper portion was known as the rudder head, and was at first an oval shaft which passed into the ship through the rudder port, and to which the helm was fixed. A canvas bag called a rudder coat covered the opening to exclude the water. In later days Sir R. Seppings introduced the cylindrical form in order to prevent the water from coming into the round rudder port. Three back pieces were fastened to the main piece longitudinally. The whole were fastened together by iron bands called pintle straps, which had at the forward end a pin or pintle, which fitted into braces, i.e. fixed rings on the stern post, so that the rudder hung on hinges. The lower part of the main piece was bevelled, and so was the stern post, so as to allow the rudder to swing freely. A projecting piece called a chock or wood-lock was fixed in the head outside the ship in order to prevent the rudder from being lifted by the water out of its hinges. A small vessel can be steered by the helm or tiller, but in a larger it is necessary to apply a mechanical leverage. This was secured by carrying ropes, or in later times chains, to the sides of the ship, and then through blocks to the upper deck, round a barrel which is worked by the wheel. The principle of the rudder cannot alter, but the means employed to work it have been altered by the introduction of the screw, and by the increased size of ships. A single screw is placed in an open space before the stern post. As the opening thus created prevents the water from flowing directly on to the rudder, a screw steamer is sometimes difficult to steer. In order to make the rudder more manageable, it has been balanced, i.e. pivoted, on a shaft placed at about a third of its length from the foremost edge. In a double screw there is no opening, but the balanced rudder is still used, and the ship can be turned by reversing one of the screws. The need for more power to work the helm has led to the introduction of steam, and hydraulic steering apparatus which can be set in motion by a small wheel.

See Burney's Falconer's Dictionary (London, 1830); Torr's Ancient Ships (Cambridge, 1894); Nares, Seamanship (Portsmouth, 1882).