Rudolf Harmstorf was the skipper of the West German 5.5 metres crew at the 1968 Mexico City Olympics in Acapulco alongside Harald Stein and Karl-August Stolze. The crew finished an unfortunate fourth and missed the podium. This The 5.5 metre class was on the Olympic Program for the final time in Mexico City. In 1966, Harmstorf won a silver medal at the World Championships. He owned the company Taucher-, Düker- und Wasserbaufirma Rudolf Harmstorf GmbH (Diving, culvert and water construction company) in Hamburg.