and yet sharks that are more fully evolved to aquatic life than dolphins have a skin like sandpaper

and currently someone has developed lumpy blades for wind turbines that seem to allow them to work better across a wider wind range. the idea being based on the knobs along the edge of humpback whale fins

http://boatdesign.net/forums/showthread.php?t=17382&highlight=whale

so i wouldn't sweat a lumpy, rough surface if i were you