I'll begin with a somewhat unrelated question: knarr security.
Others around here have suggested possibly securing knarrs by allowing them to be loaded onto an ox cart so they can be dragged into a palisade. I like this suggestion. However, I can see why the devs would not be interested in making a cart SIMPLY for that reason. I also can see why villages would not want YET ANOTHER vehicle.
My proposed solution to this would be simple: make the wagon cover separate from the wagon. Then you can have an uncovered wagon, onto which you can load a boat. And the wagon cover... might be turned into a cosmetic. Or may serve some other purpose. (So wagons cannot be stolen (as with lean-tos)? To make a mini-house, like a nomad tent? Any other ideas?)
Whatever the case, again, jorbtar, please just pick some manner of securing knarrs...