He was a national champion and representative at World Rowing Championships, an Olympian and an Olympic silver medallist.

Weightman first made state selection for Queensland in the 1990 youth eight contesting the Noel Wilkinson Trophy at the Interstate Regatta within the Australian Rowing Championships.

In UQBC colours in 1996 he won the national coxless pair title (the Ted Bromley Memorial Trophy) with Rob Scott.

[6] He rowed in the Australian men's coxed four at the World Championships in Racice 1993[6] and Indianapolis 1994 both times to a fifth placing.

[6] In 1996 he was selected to contest the 1996 Atlanta Olympics with Rob Scott in the Australian men's coxless pair.