Guys kiteboarding at those speeds can have detrimental effects on your body if you screw up or are misfortunate enough to have something fail. I remember hitting just over 82km/h and my knees felt like they were going to shatter. Good thing he was on flat water, then you just need to ask how deep it is because if you come off wrong you can either skim over the top or you go into the water like a torpedo. Top effort either way, but just trying to deter people without ideal conditions to attempt these stunts.