You need a Good Captain.
Thralls can call a "White out" while you are driving, making it impossible to see more than 3 feet in front of the boat. This makes navigation almost nonexistiant.
Really Helps if you walk to the front of the boat and look at the next two iceburgs locations BEFORE you start driving. The Steam Whistle tells thralls "This is teh time to use Whiteout" so you will want a solid look at the river before that happens.
Takes Work, but eventually those iceburgs dont stand a chance. FYI I do not think the Huge Iceburg at the end counts as it does not give you the "Crashed" symbol on the Games Summary.
GL!