Fences and hurdles or, more correctly, ‘flights’ of hurdles, are obstacles to be negotiated in different types of National Hunt race and, consequently, differ in their construction, height and rigidity. Fences, which are used for steeplechase races, are the more substantial, higher and less yielding of the two. Steeplechase fences typically consist of a rigid steel or wooden frame, filled with artificial or real birch, cut to size and bound together. With the exception of a water jump, all steeplechase fences must be a minimum of 4’ 6” in height. By contrast, hurdles, which are used, unsurprisingly, in hurdle races, consist of individual, lightweight panels of cut brushwood, each at least 3’6” in height. The panels are driven into the ground, side-by-side, at an angle, to create a ‘flight’ of hurdles at least 30’ wide and at least 3’1” high.
The term ‘open ditch’ is used to describe a type of obstacle jumped during a steeplechase race. As the name suggests, an open ditch consists of a shallow ditch, several feet wide, in front of what is, effectively, a ‘plain’ fence. Like other plain fences, the fence consists of compacted birch cuttings, bound and placed in a rigid wooden or steel frame, and must be at least 4’6” in height. However, a plain fence typically has width, or spread, of about 8’, but the addition of the ditch increases the spread to about 11’, requiring horses to jump further than at a plain fence. Under the Rules of Racing, one in six of the obstacles in a steeplechase race must be an open ditch.