  In this paper, using the classifications of timelike and spacelike ruled
surfaces, we study the Mannheim offsets of timelike ruled surfaces in Minkowski
3-space. Firstly, we define the Mannheim offsets of a timelike ruled surface by
considering the Lorentzian casual character of the offset surface. We obtain
that the Mannheim offsets of a timelike ruled surface may be timelike or
spacelike. Furthermore, we characterize the developable of Mannheim offset of a
timelike ruled surface by the derivative of the conical curvature of the
directing cone.
