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 planing dinghies as their speed generates an apparent wind on the bow allowing them to sail more directly downwind. It is also particularly useful in cruising yachts in the form of a "cruising spinnaker" or "cruising chute", where the ease of handling is important. A cruising chute is a form of asymmetric spinnaker used by cruising yachts and designed for easy use when short handed. Two sheets are used, with the tack line eased by a foot or so before gybing. Alternatively only one sheet is used, with the sail snuffed before a gybe. Many boats will have more than