Summer Eights has seven men’s divisions, and six women’s divisions, totalling 171 boats and around 1500 participants. For each division fourteen boats line up at the downstream end of the stretch, each coxswain holding onto a ‘bung-line’. The start of racing is signalled by the firing of the cannon, and each crew then attempts to progress up their division by bumping the boat in front, while avoiding being bumped by the boat behind. Once a bump has taken place, both of the crews involved stop racing, move to the side, and allow the rest of the division to pass. It is possible to ‘over bump’ by catching the boat three in front, if the two immediately in front have dropped out. Boats that have bumped then swap places for the next day’s racing.
The ultimate aim is to become ‘Head of the River’ at the top of the first division, but crews can also ‘win blades’ for bumping at least once on each day of the four days racing.