pipe storage ledge 62 and the tower and crane positioning ledge 66 with the drilling tower and tower crane 52 and 54 mounted thereon as shown in fig5 the platform is directed so that its base portion 46 first enters the region between the forward legs 26 and then continues on between and beyond the rearward legs 28 until the platform cross portion 48 nearly abuts the forward legs 26 the platform 20 is provided with jacking leg slips 72 which become aligned with the jacking legs 70 on the bridge beams 38 and 40 when the platform is floated into position these slips are designed to allow the jacking legs to move freely through then longitudinally in one direction but to grip the legs and prevent relative movement in the opposite direction as shown in fig6 the jacking mechanism 68 are then operated to lower the jacking legs 70 until they enter their corresponding jacking leg slips 72 on the platform 22 and thereby provide an interconnection between the platform and the bridge beams 38 and 40 extending across the tops of the template legs 26 and 28 as can be seen in fig8 the jacking mechanisms 68 each comprise upper and lower holder assemblies 74 and 76 with the lower holder assembly 76 mounted on a portion of one of the bridge beams 38 and.