Bob Weir is a member of the 24-hour club due to his solo marathon swim of 35 miles (56 km) on 23-24 August 1991 in 25 hours 8 minutes at the age of 48 from Wasago (Lake Couchiching)to Barrie (Centennial Park), Canada.
A former competitive age-group swimmer, Weir swam 18 miles across Lake Winnipeg in 9 hours 57 minutes in 1962. In 1963, he became the first person to swim across Lake Manitoba (34 miles) in 25 hours, 10 minutes. He swam on the 1964 professional marathon swimming circuit where he competed in the 24 Heures La Tuque where he finished fourth with teammate John Lumgair. he also swam across Lake Ontario in 1989 in 22 hours 8 minutes. In 1992, he swam 27 miles (43 km) across Lake Erie in 23 hours 41 minutes from Dunkirk (New York State) to Mohawk Point (near Dunville, Ontario). In 1993, he joined the Half Century Club at the age of 50 when he became the first person to swim the 21 miles of Lake Winnipesaukee in 12 hours from Center Harbor to Alton Bay.
Weir is the President of the Solo Swims of Ontario since 1992. In 1996, he received the Cliff Lumsdon Award of the Solo Swims of Ontario for his achievements and contributions. He was the president of Masters Swimming Ontario from 1991 to 1994.