More than 300 boats have registers for the 10th Chicago Yacht Club Race to Mackinac presented by Wintrust, one of the world's longest-running freshwater distance races. "The Mac", which takes most competitors well over 24 hours to complete, is a 333 mile sprint from the Chicago Lighthouse, just east of Navy Pier, to the Round Island Channel near Mackinac Island, Michigan. This year's race kicks off on Saturday, July 15.