When you buy a boat from someone, there's no obligation to transfer the registration. In fact, there's a disincentive, because as soon as you transfer the registration you have to pay GST. If I bought a boat and transferred the registration to myself, I'd have to pay GST, which is an interesting point. Because of the lack of legislation around this, the federal government has missed out on a lot of GST revenue over the years. Right now it's a disincentive for people to transfer it, and frankly, they don't. I could name dozens of boat owners who have not transferred ownership and have avoided paying thousands of dollars' worth of GST.
On February 14th, 2018. See this statement in context.