Simple answer...
The rudder folds up. It's that simple. You can pull it up manually while standing in shallow water, or you can remove the rudder, pull it into the boat, and pull it into a folded position. Or...if you drift into too shallow water, the rudder will drag on the bottom and that will cause it to fold. Of course, dragging will also damage the tip of the rudder. At least that's how it is with my boat.
