is wasted in twisting the boat. Sliding seats A rower on a fixed seat is limited in the amount of power he can apply to the oars by the strength in his upper body and the distance he can pull the oars on each stroke. After riggers were added to the shell allowing the use of longer oars, rowers took advantage by taking longer strokes and using their legs during the stroke. At first, the athletes wore trousers with wear resistant leather bottoms covered in grease and the shells had concave, longitudinal seats. The athletes could then use their legs to slide along the seat, adding the power of their legs and letting them greatly lengthen the stroke. This eventually led to the modern sliding seat, mounted on rollers, commonly called the slide in the rowing community, which allows nearly frictionless movement of the rower's body. Rolling seats were introduced around the year 1880. They differed from modern seats in that ball bearings were not available. Several inventors produced designs which avoided the friction which would result from use of a simple axle and bushing design. Patents were granted to Octavius Hicks (1880), George Warin (1882), and Michael F. Davis (1882). Hicks, of Etobicoke, was a boat builder, hotelier, road and bridge contractor. Warin, of Toronto, a boat builder and famous decoy maker, was coach to world rowing champion Ned Hanlan. With the advent of the sliding seat, Hanlan was able to greatly outperform his English and American counterparts. The Davis seat used rollers in a race similar to a ball bearing. Sliding rigger The same advantages may be obtained by fixing the seat and mounting the outriggers on rollers. Now the athlete's body mass remains stationary and the boat doesn't pitch bow to stern nearly as much. This improves the boat speed significantly. The disadvantage is that this arrangement may result in blisters on one's buttocks and in the risk of sliding off one's seat when exerting too much explosive force at the beginning of a race . In April 1877 Michael Davis of Portland Maine applied for a patent for a sliding rigger/foot-board with fixed seat. In 1981, the German Peter-Michael Kolbe won the FISA World Championship using a sliding rigger. In August 1983 FISA banned the use of the sliding-rigger, presumably because it was thought to be more costly than sliding-seat boats. Boat classification There are a