I agree that it's consistent across the literature, but a lot of factors go into the impact. A lot of that has to do with shoreline habitat as well. If the shoreline has its natural vegetation there, including aquatic plants, the impact tends to be less, because the vegetation reduces wave energy.
In terms of regulating boats for shoreline erosion, I think it's also important to think about the shoreline itself and what that looks like in terms of its vegetation and also its slope and topography and things like that.