Representing Huanui College at the Maadi Cup earlier this year, Johnston and Greenhalgh came fourth in their under-17 girls' double sculls A final.
As well as this they placed sixth in their quadruple sculls A final with Maddie Parker and Alex Godman, coxed by Greg Hamlet.
Selected to trial for the North Island under-18s, Greenhalgh spearheaded Huanui's growing status as a competent rowing school.
Now both girls are ready to take the next step.
"We don't row that much compared to all of the other schools, they row 10-11 times a week and we row like five," Greenhalgh said, "but we're aiming for the New Zealand juniors next year.
"We put all of our credit to our coach Simon Koller, he's done really well and Evan Hamlet has done really well organising it all."
Of the Rockhampton competition this weekend, the Huanui duo said the new experience would be something further to add to their growing resume of rowing nous.
"It's harder because the girls in Australia are peaking now," Greenhalgh said.
"Our timing needs to be precise, we just have to do everything in time and together."
-The Auckland Light Blues is a development pathway for talented Year 12 rowers.
The programme consists of six weekend "mini camps" run by the Auckland Rowing Association at various clubs around Auckland. At the conclusion of the camps a squad is selected to represent at the Queensland Schools Championship Regatta.