: If you consider than frictional resistance increases at an approximately
: exponential rate as velocity increases, minimizing the drag due to surface
: finish is important to minimizing the effort required to paddle a kayak at
: any given speed (where wave drag is not coming into play). The only link I
: have at hand specifically dealing with kayak surface finish is by John
: Winters (see below); he notes that typical wear and tear of a hull's
: surface could easily double the coefficient of friction over a single
: season, which is not a trivial increase, since the increase in the
: coefficient of friction will give you a linear increase in drag for a
: given velocity.

: So, 50% increase in the coefficient of friction due to a rougher hull surface
: will cause a 50% increase in effort to maintain the same speed you were
: capable of before the surface was damaged.

Doesn't a direct relationship assume that the only force a paddler is overcoming is friction? I'd expect friction to be secondary to just having to displace the water as you move forward.