"Friction" is usually in reference to two solids in contact. "Drag" is the more common term to refer to the resistance boats encounter when they slide through water. Mick could probably give us a thorough treatise on the various forms. And, what is known about the factors which enhance drag.
Turbulence, for example, often increases drag, but is unavoidable. Airfoils passing through air, however, perform better if there is a little turbulence introduced just forward of the maximum thickness of a wing. In models, a very thin thread is sometimes glued to the wing there, running spanwise, from the body of an aircraft to each of its wingtips. Counterintuitive, no? Such turbulators probably have hydrodynamic counterparts, also. Something to consider as you shave the hairs off that plastic hull.
Hydrodynamics is half guesswork, half empirical knowledge, and half witchcraft. Yeah, does not add up. Because hydrodynamics depends in nonlinear physics, where a tiny change can produce a large effect, aka "the butterfly effect," much bandied about after many natural systems were shown to follow the precepts of chaos theory. Weather, turbulence, and lots of others.
Maybe the bottom line on whether to wax or not, shave the hull or not, comes down to try it, and then measure the effect on hull speed in quantitative testing. Yeah, get some repeatable numbers.
EDIT: Designer and I crossposted. Surface roughness, which many think can reduce hydrodynamic drag, is an effect like that of turbulaters on airfoils.