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 raise the sail up the mast. Symmetric spinnakers have the windward clew secured to a spinnaker pole. The pole is attached to the mast and holds the windward edge of the sail in position. Lines that control the spinnaker pole are called "guys" or "braces". The spinnaker pole may be allowed to raise and lower with the force of the wind, or it may have lines attached to it to raise (the "topping lift") and lower (the "foreguy" or "downhaul") the angle of the pole. If these lines are used, they are generally set up before setting sail, and left