He was first selected to represent Queensland in the men's youth eight who contested the Noel F Wilkinson Trophy in the Interstate Regatta within the 1998 Australian Rowing Championships.

On seven occasions between 2001 and 2008 he rowed in the Queensland senior men's eight contesting the King's Cup at the Australian Interstate Regatta.

[3] They contested those same national titles in 2006 and in a composite selection trial crew with Drew Ginn and David Crawshay from Mercantile they won the Australian men's coxless four championship and were presented with the Bob Aitken Memorial Trophy in the first year it was awarded for that event.

[8] Cubasch next figured in an Australian representative crew in 2005 when he was picked to race a coxed pair at the 2005 World Rowing Championships in Gifu, Japan with Sam Conrad at stroke and Marc Douez up front.

The pair led the race from start to finish and claimed Australia's second ever World Championship title in that boat class.