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 top for easy access. While a symmetric spinnaker is flown with a "guy" and a "sheet", an asymmetric spinnaker is flown with a tackline and a "sheet." The tack attaches to the bow or (often retractable) bowsprit, and the two sheets attach to the clew. The head of the sail is attached to the spinnaker halyard, which is used to raise the sail. The sheets are passed to either side of the forestay, attached to the clew; they may be passed forward of the luff of the asymmetric, or aft of the luff of the asymmetric, between the tack line