A drillstring comprising a length of drillpipes and a bottomhole assembly disposed at a downhole end of the length of drillpipes. The bottomhole assembly comprises a transition section proximal to the end of the length of drillpipes to reduce vibration of the bottomhole assembly during drilling. The transition section varies gradually in acoustic impedance between the acoustic impedance of the drillstring above the transition section and the acoustic impedance of the bottomhole assembly below the transition section. The transition section forms at least thirty percent (30%) of the total length of the bottomhole assembly.