It was nice of Bean to volunteer to be the size reference. The alleged Alcatraz escapees really did build a raft out of raincoats that they intended to use to cross the San Francisco bay. If Potato can't get raincoats, he might as well use duct tape.
I don't think Potato's ever actually been in the laundry room. He's not bound to find a lot of raincoats, anyway. At least not around here, in Southern California, where it rains only a few times per year.