The jack up drilling ENSCO 100, on the River Tay, being towed towards Dundee. The rig was built in Clydebank in 1986, and has spent her whole working life in the North Sea. No doubt a testament to the skills of the Clyde shipbuilders. The rig is capable of drilling to a depth of 30,000 feet, whilst standing in 350 feet of water. This is the typical depth of the Central North Sea.