To me Marine Traffic is a reliable source using vessel owner/operator data. I used "Marine Traffic data transmitted at time of shot:" because of the issues raised by davidships.

It is not unusual for marketing people preparing web sites to be less accurate than technical administrators.

My thanks to all who commented. The photo was a bonus one to me, captured on the way to the tanker down the road http://www.shipspotting.com/gallery/photo.php?lid=2692386

Detective work needed, Clyde!
According to their own website, Sydney Showboats now call this vessel HARBOUR BALLROOM
https://www.sydneyshowboats.com.au/more-info/about-us

This is supported by your 2014 photo that clearly shows
SYDNEY SHOWBOAT painted out on the stern and HARBOUR BALLROOM name on the side.
http://www.shipspotting.com/gallery/photo.php?lid=2149700

However, AMSA still list this as SYDNEY SHOWBOAT (ignore Equasis, as they just follow what AMSA have) and, as you note, the AIS signal is still using SYDNEY SHOWBOAT.

So perhaps this is an unofficial "renaming" (but then the AMSA requirements on marking Australian-registered ships would appear not to be observed). Over to you!

Apartment's balcony in the background? Nice photo...
near my house also has many area for drydocking, but regret can't free going inside for photos

Wow... thank you, Clyde, for posting this very-very interesting photo, and moreover, it's a much unusual one (the *boat*) for your standard photo opus; best regards to you and Sydney /jadran