Harvard-Yale Boat Race which cover courses of approximately . The Henley Royal Regatta is also raced upon a non-standard distance at 2,112 meters (1 mile, 550 yards). In general, multi-boat competitions are organized in a series of rounds, with the fastest boats in each heat qualifying for the next round. The losing boats from each heat may be given a second chance to qualify through a repechage. The World Rowing Championships offers multi-lane racing in heats, finals and repechages. At Henley Royal Regatta two crews compete side by side in each round, in a straightforward knock-out format, with no repechages. Head races Head races are time trial / processional races that take place from autumn (fall) to early spring (depending on local conditions). Boats begin with a rolling start at intervals of 10 – 20 seconds, and are timed over a set distance. Head courses usually vary in length from to , though there are longer races such as the Boston Rowing Marathon and shorter such as Pairs Head. The oldest, and arguably most famous, head race is the Head of the River Race, founded by Steve Fairbairn in 1926 which takes place each March on the river Thames in London, United Kingdom. Head racing was exported to the United States in the 1950s, and the Head of the Charles Regatta held each October on the Charles River in Boston, Massachusetts, United States is now the largest rowing event in the world. These processional races are known as Head Races, because, as with bumps racing, the fastest crew is awarded the title Head of the River (as in "head of the class"). It was not deemed feasible to run bumps racing on the Tideway, so a timed format was adopted and soon caught on. Time trials are sometimes used to determine who competes in an event where there is a limited number of entries, for example, the qualifying races for Henley Royal Regatta, and rowing on and getting on for the Oxford and Cambridge Bumps races respectively. Other race formats A bumps race is a multi-day race beginning with crews lined up along the river at set intervals. They start simultaneously and all pursue the boat ahead while avoiding being bumped by a boat from behind. If a crew overtakes or makes physical contact with the crew ahead, a bump is awarded. As a result, damage to boats and equipment