My first thought upon reading the article is that a boat or ship does not fall into disrepair, it comes into a state of disrepair through a lack of on going work upon it, having said that it is a shame that this vessel was allowed to get into such a sorry state in the first place, and how could vandalism be the reason this boat sank, It sounds more like wilful damage than vandalism to me, dare I suggest maybe an insurance job?
Yes that makes much more sense than the first article, strange that two different news articles can be so different in their views about the same event, but then the ABC has never been known for allowing facts to dictate their view of the world.
We had the Alma Dopel [of similar size] resting in Port Macquarie for a few years and when I was loosely associated with it I had to dash home several times for my scuba gear to apply patches underwater in areas that had opened up. Interesting exercise trying to locate water coming in when it sounds like someone has left a hose on!!