Link doesn't seem to work.
The boats are known as "Log Bronks" and they are used to sort and build log rafts or to break down log rafts and get them up into the sawmill, Many are powered with 4-53 Detroits. They are very deep drafted and tough to sink.
Sidewinders were what we called the ones with 360* drive. d.d.I always find it interesting how different areas use different names for things. I've always known them to be boom boats, or dozer boats.