For the record, hitting a cast iron tub with a sledgehammer *does* break it into pieces, and I have to imagine that the two hours of work (or so) was way better than trying to carry it out of the house intact. The tub is destroyed, no injuries were sustained, and we’ve got a pretty decent story.
That said, you have to hit the tub really damn hard. There is to be no (in the words of capital_l) ‘panty waist’ hitting.
Here’s early in the process
And, near the conclusion.