Forces due to contraction on a cord spanning between two spaceships

A formula is derived estimating the additional tensile forces which a cord must be able to exert to support the Lorentz contraction of itself and of two spaceships, positioned line-ahead, which it spans between, as those ships steadily and identically fire their thrusters. It is found that even a spider's thread of length one metre can exert the forces required to reach half light speed in less than half an hour between ships each weighing a hundred metric tonnes. A critique is also provided of previous published work in this area.