Before you board the ferry, Sara will give you her shawl. Once you're on the bridge, talk to the captain of the latest problem you'll have to face. The lake is covered with thick ice, preventing you from going any further. Leave the bridge using the stairs on the left. Head to the other side of the quarterdeck, and then to the engine room, once again taking the stairs on the left.
There, take another stairs to get off the catwalk (to the right) and head for the icebreaker control panel located to the center of another catwalk. Take a close look at the panel.
Zoom in, and turn left the valve (mouse movement) as far as you can, then raise the transparent cover of the button located below the valve (move the mouse up), and press the said button - after several attempts to shift gears, the captain will call your from the bridge. Talk to him through a voice tube and Obo will instruct Kate what to do.
You'll have to perform, in the right order and rather smoothly, the following maneuvers (assuming you've already turned the valve and raised the button cover - you don't have to do it again): push the button on the right, move the gear stick (with your mouse) to 1, pull down the lever (mouse) on the center, move the gear stick (mouse) to 3, and then to 2. (If you fail to do this the first or second time, the sequence will have to be repeated until you succeed - until Kate will be able to open a channel in the ice for the ferry). (If you fail during the process then you must repeat the whole sequence until you complete it - when Kate goes through the ice by using the ferry, however, if you make it during your first attempt, you will receive Ice breaker achievement).