Surf ski  A surf ski is a long, narrow and lightweight craft similar to a kayak but with an open "sit-on-top" (SOT) cockpit and a self-bailer to eliminate water instead of the enclosed kayak-style cockpit which can be sealed against the elements with a sprayskirt or tuliq. Surfskis are primarily designed for speed, including fast runs on the open seas, and have a powerful, pedal-operated rudder to control the boat while surfing on wave fronts. There are two types of surf skis, the spec ski and the ocean ski. The spec ski is the traditional craft used by surf life saving clubs and must adhere to strict size and weight. The ocean ski on the other hand is typically a longer craft with a deeper cockpit. The Spec ski is designed tougher and with more rocker to manoeuvre in and out of the wave zone. The ocean ski is made for long-distance ocean paddling and is usually raced downwind with the swells. Typically 5.0-6.0 metres(16½-21 ft) long and only 40–50 cm (16-20") wide, surf skis are extremely fast when paddled on flat water (only an Olympic K1 or K2 kayak is faster) and the fastest paddled craft available over a long distance on ocean swells. They track well but are less manoeuvrable and have less transverse primary and secondary stability than shorter, wider craft. Despite its typical instability, a surf ski (with an experienced paddler) is a very effective craft for paddling in big surf. Its narrowness and length helps it cut or punch through large broken waves. Double-bladed paddles are used, often with highly contoured wing blades for extra efficiency. A waveski is a type of short surf ski similar to a surf board, used primarily in surf play. It is usually less than 3 m (10 ft) long, typically with a wide planing type bottom and with one to three fixed skegs, or fins. Surf skis are used worldwide for surf lifesaving, wave surfing and for training and competition on flat-water or ocean (downwind) racing. They are most popular in warmer coastal regions such as Australia, California, Hawaii, and South Africa, as paddling a surf ski inevitably involves contact with the water. In cooler waters, paddlers often wear a wetsuit or drysuit. Some cheaper, heavier surf skis are made from polyethylene.