ICEBREAKER HULL MOVEMENT
"USCGC MACKINAW resting in
ice on the Great Lakes. The
famous and popular ship has three
propellers - two at her stern and
one at her bow. She can thrust
herself up on ice to break it and
heel side to side by quickly shifting
112,000 gallons of ballast water
to assist in breaking ice"
.
http//www.glsps.org/newsletter_archive/Newslet05s.pdf