Clocks will be located at every mile and 5 km mark along the course (clocks will display the elapsed time from the 10:00 a.m. start only - Wave 2 runners simply need to deduct 25 minutes from the displayed time, Wave 3 runners must deduct one hour from the displayed time, and Wave 4 runners must deduct 1 hour and 25 minutes from the displayed time.) Boston Marathon Course Information Will there be clocks along the Boston Marathon course?