If you're coming by public transport, the best way is to walk from North Sydney station.
Coming out of the station, up the stairs onto Blue Street (don't go into the underpass which leads into the Greenwood shopping center), turn right and walk down Blue St. Alongside the Harbourview Hotel you will see a set of steps leading up. Follow these and walk alongside the hotel, eventually you will go over the carpark and end up on Walker St. Follow Walker St down, cross at the crosswalk and you will end up next to the Indian restaurant on Lavender St. There is a set of steps and path leading down to the waterfront from there, it goes under the old railway line. When you reach the waterfront, turn right and you will see the Sailcorp marina and wharf.
Sailcorp run a tender service from 9:30am to 4:30pm every hour on the half hour (so 9:30, 10:30, 11:30, etc). Tell them you want to go to Chiara Stella aka the red boat and they will know which one it is. The tender is a fairly large electric powered barge that seats about 8 or so maximum. If you're coming on New Years' Eve then tenders need to be booked and cost $10pp (so probably what will happen is I will collect people from the beach at Quiberie Park in my dinghy).