  Let K be a knot in $S^3$ and $X$ its complement. We study deformations of
reducible metabelian representations of the knot group $\pi_1(X)$ into
$SL(3,\mathbb{C})$ which are associated to a double root of the Alexander
polynomial. We prove that these reducible metabelian representations are smooth
points of the representation variety and that they have irreducible non
metabelian deformations.
