The Army Corps of Engineers had MV Mississippi in Saint Paul today, and I went down to have a look around. She's 241 x 58 and the pilothouse is about 5 stories over the waterline. Three Caterpillar 3606's, putting out 6,300 HP and driving 93" props, get her around just fine.
MV Mississippi's main role is to move and secure the barges and other equipment that's used for sinking concrete mat systems that stabilize river beds; no small feat on the southern Mississippi River.
Did I mention it's a big ol' boat?