Barb is in debt. A lot. Since the house is pretty much all she owns that's worth anything, the creditors get first dibs on her stuff to help payback the loans. Chris would have to have enough to pay off her debts (lol).
Plus, the tugboat is probably not enough to pay off the second mortgage, property taxes, bills, etc... and still have enough for his spending habits. He might try to hold on for a while, with donations from his paypigs coming in, but he frankly just can't afford it.
With the tugboat, though, he will have no trouble getting a crappy apartment.