He became a very active competitor in sailing, winning medals at World, North American and National Championships.

Henderson has represented Canada at three Olympic Games: 1964 Enochima in the Flying Dutchman, 1968 Acapulco in the Finn and at the 1972 Schilksee as coach.

He was a member of the founding group that set up CORK (Canadian Olympic Regatta Kingston) The first time Henderson represented Canada at the International Yacht Racing Union, was in 1970 to advise on the sailing venue for the 1976 Montreal Olympics.

Henderson was elected President of the ISAF in 1994; the first non-European to ever hold this position.

They have two children, John and Martha; the latter represented Canada in the 2008 Olympics as crew member on the Canadian Yngling.