What is a surfski?

(Above: The NZ-popular Flow Kayaks Sharpski elite racing ski. (Courtesy of Flow Kayaks))

A surfski is a long, narrow, lightweight kayak with an open (sit-on-top) cockpit, usually with a foot pedal controlled rudder.

There are two types of surfskis, 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 maneuver 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, surfskis 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 maneuverable and have less transverse primary and secondary stability than shorter, wider craft. Despite its typical instability, a surfski (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 surfski 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.

(Much of the above is courtesy of Wikipedia - see www.wikipedia.org/wiki/Surf_ski for further info.)