Unfortunately for the Duchess, she was awarded the wooden spoon for her yacht's poor performance, but it's safe to say she got the last laugh when her daughter made her thoughts on the matter known (we can only assume, of course) at the winner's ceremony.
Ahead of the first race, the boats were recalled to the starting line after an initial false start in which some of them were over the line.
The event was due to take place tomorrow (Friday) but anticipated weather forced organisers to push things forward by 24 hours.
Each boat represented one of the charities being supported by the Duke and Duchess.
Prince William and Kate Middleton took a quick intermission from their annual summer vacation to engage in a little friendly competition. Kate Middleton wore shorts (!) and rocked a ponytail.
William's boat finished the race third while Kate came in seventh in the first race. In the second race, Kate's boat was disqualified.
Kate chose four of her patronages and promoted the Royal Foundation, in connection with her work on the early years development of children.
The royals were also joined by Olympic champion rower Helen Glover, who represented the Anna Freud Centre, stand-up comedian John Bishop for Action on Addiction, BBC presenter Katie Thistleton for Place2Be, England women's soccer player Fara Williams for Centrepoint, television presenter Dan Snow for London's Air Ambulance Charity, and Bear Grylls for wildlife conservation organization Tusk.
Members of the public were able to watch the race from the SailGP Race Village along the Cowes foreshore, which is free to access and will include an 800-seat grandstand.