People think lots of things are good boat names. There's no reason there couldn't have more than one Unsinkable that hadn't sunk, and most boats aren't retired by sinking, so Unsinkable II would fit right in.
What about "Really Actually Unsinkable 9"?
Following in the footsteps of "The Hand of God 137"
If I buy a yacht I'd name it "The Ends of Invention" - have been keeping that name handy for almost 40 years since I read CP in a oner in May 1988.
You're missing the "You're absolutely right" prefix
Parent reply is actually way funnier and more original than the GP, which has already been repeated by two other posters.