But we waited busily. Were indeed a few loaded barges; these we unloaded and reloaded with rock, with changes made in guidance transponders so that Poona Control could not affect them. Their retros were removed, leaving only lateral thrustors, and spare retros were taken to new catapult, to be modified for lateral guidance. Greatest effort went into moving steel to new catapult and shaping it into jackets for solid rock cylinders—steel was bottleneck.