Aaaaah I see the problem. For what it's worth and at the risk of offending my Melbourne mates - here are some thoughts.
Melbourne does not have a lot of choices as far as affordable and sheltered marinas. Port Phillip Bay can get pretty rough at times and the general view is that it is under serviced in this area. Many vessels are moored but now with the new dredging of the entrance to the bay, the whole coast line is undergoing massive transformations as the increased water flow reeks havoc on the shorelines with the increased swells coming through. We have friends on moorings down at Portsea and along the coast back up to Melbourne on moorings and they are finding themselves being battered to blazes. It seems to be the case the more sheltered a position you seek (either mooring or marina) the prices go way up.
Port Phillip Bay and it's surrounds does provide some pleasant sailing ground but due to colder weather and shallowing coastlines - sailing opportunities are far more limited than up in Queensland where ther are more varied and the mooring and marina costs are far cheaper.
The friends I spoke about, like a few others we know have come to the conclusion that in order to increase their sailing opportunities and reduce costs, they are going to bring their yachts up to Bundie, Mackay, Whitsundays or even Cairns; leave them there and then fly up for sailing holidays. A sort of fly in fly out with cheap airfare now being readily available if you book ahead.
If you are not anticipating sailing a great deal down in Melbourne and this is purely a work issue - I'd leave it on the hard or in a marina up here in Queensland and when your get the urge and the opportunity - fly back and sail her in warmer and more varied sailing grounds.
While now being a Queenslander, I did grow up in Melbourne and sailed the bay there so I'm not totally biased but while down in Melbourne a few months ago we had a look over a number of marinas and turned to each other as we stood in our jumpers, thermals and overcoats, and said - gawd - why would you? (sorry Melbournites
As is heard a fair bit over here 'want more sailing fun? then come to the sun'
Mico (ducking for cover as my Melbourne mates pick up there baseball bats and come a hunting)