MorningBird said..
A yacht with its engine running, sails up or down, is considered a power vessel even if the shaft isn't engaged. You were the stand on vessel on this occasion and he should have given way.
It would be worthwhile getting a power boat licence even if it isn't necessary for your vessel so that you are confident of your responsibilities. Nobody at sea has rights (you are just the 'stand on' vessel), we just have responsibilities.
Unless its during the Sydney Hobart race and the engine is running to drive the hydraulics and electrics!
It's always better to avoid a collision than being right!
Also on the harbour if it's the Sydney harbour there are other rules.