A spar is a marine structure, used for floating oil/gas platforms. Named after navigation channel Spar buoys, spar platforms were developed as an extreme deepwater alternative to conventional platforms. The deep draft design of spars makes them less affected by wind, wave, and currents and allows for both dry tree and subsea production. There are three primary types of spars; classic, truss, and cell. A classic spar consists of a tall-height, cylindrical hull, with tanks for heavy ballast located at the bottom of the cylinder.