With the up and coming kingdoms update, I think it would be fun to have a larger version of the rowboat, kind of a viking rowship that would hold up to 4-8 people for example.
Also, maybe make it easier to shoot from a boat.
At the current world this woul probrably not have much impact because most rivers are not conected and don´t really take you anywhere, perhaps on a future world the map generator will allow for such a ship to work better, and maybe make naval warfare possible?