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 race the next year. Start time is usually about 2 hours after high tide and crews start at about 10 second intervals.