My recommendation would be to join a Game Club, If you fish around Sydney there is plenty of good ones on offer.
What part of Sydney do you live in and where is the boat moored?
Very nice fish indeed on 15kg tackle, congratulations.
It was also very nice of the guys from SGFC to weight it for you.
For the guys that only use heavy tackle for these sized fish, see it is possible, another win for the T&R Line Class Debate.