As the length of the racing course is limited, large
regattas are organised into
divisions of 12 to 20 boats. Each division races separately, but they are ranked to achieve an overall order of crews: e.g. the top crew in the second division is considered to be one place behind the last crew in the first division. The first day's starting position is based on the final positions from the previous year, though in the bottom divisions the boats may be placed according to qualifying
getting/rowing on races held before the event. This allows boat clubs to introduce new crews. On each day of a bumps regatta the division races are rowed in reverse order, i.e. the lowest division first. A crew finishing at the top of a division race goes on to compete in the next-higher division later that day (starting last). Alternatively, a crew finishing last in a division must race in the next-lower division the following day (starting first). This is referred to as a
sandwich boat and allows crews to move between divisions. The crew of a boat (hereinafter "crew A") may find that the boat in front of them ("boat B") has caught the boat ("boat C") ahead of boat B. Since (except at Oxford during Torpids) these boats both then drop out, crew A must now try to catch the next boat ahead of them still racing (most often the one which started three places ahead). If crew A succeed, this is called an
overbump and, in exchanging places with the boat that they bumped, they move three places up the start order. Further still, it is possible, though very rare, to
double-overbump (move up five places) or
triple-overbump (seven places). Only two occasions of a
quadruple-overbump (9 places at once) have been recorded at the Cambridge
May Bumps, by W1 in 1986 and by M4 in 2018. A
quintuple-overbump occurred in the 1984 Cambridge May Bumps in Men's Division 6 when Downing V caught Corpus IV after the 10 sandwich boats originally between them had all bumped out. Overbumps, and variants thereof, are most common in the lower divisions where the quality of the crews varies greatly year-on-year. The ultimate achievement in such a competition is to finish first in the overall order; that crew is said to be 'Head of the River'. This is only realistically possible for crews starting a bump race in the top few places. A more attainable goal for most crews, apart from moving up towards the headship, is to bump up a place (or more) on each of the four days. The crew is said to have "won its blades", or achieved
blades. Traditionally, members of such a crew can purchase a rowing oar in the crew colours and inscribed with the crews' names and the boats they bumped to hang on their wall. Conversely, crews that go down four places win a wooden spoon, achieving
spoons. The bottom crew at the bottom of the last division is known as the 'Tail of the River'. A
bumps chart is a graphical representation of the week's results; each boat's fortunes can be traced as its line on the chart rises and falls. At Cambridge, the most successful college boat club over the four days of the May Bumps is awarded the
Pegasus Cup, sponsored by
Milton Brewery. celebrate the double headship of the
Lent Bumps 2007 by burning a boat, the
Fair Maid of Kent. ==Races==