A tensioner structured to shorten the effective length of a tension member is provided. The tensioner has a body with an outer surface and a generally helical path on the outer surface. The tension member is wrapped around the tensioner body and retained in the path. In this configuration, the tensioner acts to retain a first length of the tension member within a second, shorter length corresponding to the length of the tensioner body. When the effective length of a tension member is reduced, the amount of sag in the tension member is reduced.