Emirates Spinnaker Tower two large, white, sweeping metal arcs, which give the tower its spinnaker sail design. The steelwork was fabricated by Butterley Engineering. At the top is a triple observation deck, providing a 360° view of the city of Portsmouth, the Langstone and Portsmouth harbours, and a viewing distance of . The highest of the three observation platforms, the Sky Deck, has only a wire mesh roof, so visitors are open to the elements. The windows extend above head height, so it is not possible to get a view unobstructed by glass. A glass floor is located on the first viewing deck
Spinnaker Spinnaker A spinnaker is a sail designed specifically for sailing off the wind from a reaching course to a downwind, i.e. with the wind 90°–180° off bow. The spinnaker fills with wind and balloons out in front of the boat when it is deployed, called "flying". It is constructed of lightweight fabric, usually nylon, and is often brightly coloured. It may be optimised for a particular range of wind angles, as either a reaching or a running spinnaker, by the shaping of the panels and seams. The spinnaker is often called a "kite", or a "chute" (as in cruising chute)