Head of the River Race only open to men's eights and is considered to be the peak of the head race season — attracting the top UK crews as well as foreign clubs. Composite crews, drawn from more than one club or institution, are not permitted. The Championship Course is that of the Oxford and Cambridge Boat Race but, unlike the Boat Race, the Head of the River Race is raced on an ebb tide from Mortlake to Putney. The starting time for the race is different every year and depends on the tide — the first crew (winner from the previous year) starts the
The Boat Race in 1951; the 1951 race was re-rowed on the following Monday. In 1984 the Cambridge boat sank after colliding with a barge before the start of the race, which was then rescheduled for the next day. In 2016, at Barnes Bridge, Cambridge women began to sink and received advice from the umpire to pull to the side. The Cambridge cox indicated that she wanted to continue to complete the course and was allowed to do so. The course is 4 miles and 374 yards (6.779 km) from Putney to Mortlake, passing Hammersmith and Barnes; it is sometimes referred to as