Prior to his two overall wins, Mr Galbraith had achieved two third placings at the nationals and he has competed at the Hawke's Bay regional competitions more than a dozen times.
The national competition was staged as part of the Central Districts Field Days held in Fielding.
Big crowds turned out as the two Hawke's Bay earthmoving experts, along with nine other competitors, had to impress the judges not only with highly advanced excavator operation techniques but also with their knowledge of health and safety precautions and planning.
The were assessed during the four-part competition on skills as diverse as using a 13-tonne excavator to peel a watermelon to first-aid skills and teaching a toddler how to operate a 1.7 tonne digger.
Competition manager Tricia Logan said Mr Galbraith and Mr Mephan were "outstanding operators" as the field was particularly strong this year and it turned out to be a tight finish.
"All the competitors had demonstrated a very high level of skill, knowledge and excellence and are at the very top of their game," Ms Logan said.
The national competition is staged to raise the profile of a growing industry which is embracing new technology.