Spinnaker Tower, soaring 170m into the sky at the entrance to Portsmouth harbour has been constructed with a steel framework produced by Angle Ring. The framework had to be curved to accommodate the elegant design, but also had to be extremely strong to resist the high winds blowing in from the channel and the possibility of a vessel hitting the tower?s base. Assembled on a platform50x30m out in the sea, the steel frame supports the tower?s steel sail, stretching 120m and weighing 1100 tonnes.