a wrote:
 Paddle wheels got screwed. It's just another demonstration that the
 spinning thing belongs on the back of the hull.
Except when it belongs in the front.
"At full load the Mackinaw displaced 5,252.4 tons and drew 19' 2.25" of 
water. Her innovative features included a 12 foot diameter bow propeller 
which draws water from beneath the ice ahead, both weakening the ice and 
sending water along the sides of the hull and reducing ice friction. The 
Mackinaw also has a heeling system which can shift nearly 112,000 gallons of 
ballast water from side to side in 90 seconds, allowing a rocking motion 
which assists the Mackinaw in freeing itself from ice."
http://www.mightymac.org/cgcmackinaw.htm