Gavin Hassett took up rowing in 1989 and made the Canadian national team in 1993, where he won a gold medal in the eights alongside Dave Boyes, Jeffrey Lay, Pat Newman, Brian Peaker, and the non-Olympians Christopher Cookson, Robert Fontaine, Peter Sommerwil and Bryan Thompson. From that point on, he competed almost exclusively in the lightweight coxless fours, beginning with fourth-place finishes at the 1994 and 1995 World Championships (with Fontaine, Lay, and Thompson and Boyes, Lay, and Peaker respectively). His 1995 crew improved the following year and took silver in the event at the 1996 Summer Olympics, losing the gold by just over half a second to the Danes. Hassett did not see the World Championships again until 1999, when he Jon Beare, Iain Brambell, and Chris Davidson finished sixth. The quartet finished seventh at the 2000 Summer Olympics, and then traded Beare for Jon Mandick to finish fifth at the 2001 World Championships. Doug Vandor replaced Davidson for the 2002 edition, and the crew finally returned to the podium by earning a bronze medal. They slid to fifth the following year and Vandor was exchanged for Beare in time for the 2004 Summer Olympics, where they again placed fifth, after which Hassett retired from active competition.