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 pole of the pole, out to windward over the side of the boat. There, one of the control lines of whichever sail it is to be used with is run through a fitting on the other end of the spinnaker pole. This allows for more precise control of the corner of the sail to which the line is attached. For a spinnaker, the line attached to the pole is the guy, or brace, and the corner is the tack. For other headsails, such as a jib, the line would be the sheet, attached to the clew. A special line, the topping