Every year the colleges that make up both Oxford and Cambridge compete among themselves for the honour of being the best college rowing crew at that university.
Crews are set off in procession along the river and the goal is to achieve an overlap of the preceding crew’s stern by that crew’s bow without allowing the following crew to overlap ones stern with their bow. In year’s gone by a physical collision or ‘bump’ was required to achieve victory but the cost of equipment and safety concerns have curtailed the practice.
Once overlap is achieved then that crew moves up a place in the ladder and will start the next race in that position. Naturally the losing crew will move down a place.
Each college uses the racing to showcase the talents of individuals within their respective college crew and thereby hopefully earn them a place to represent the entire university. Those who reach that pinnacle earn their colours for the university which by their nature are referred to as ‘Blues’