  The chirality of Damon-Eshbach (DE) magnons affects the transport of energy
and angular momentum at the surface of magnetic films and spheres. We calculate
the surface-disorder-limited dephasing and transport lifetimes of surface modes
of sufficiently thick high-quality magnetic films such as yttrium iron garnet.
In spite of their chirality surface magnons are not protected, but interact
strongly with smooth surface roughness. Nevertheless, for long-range disorder
the transport is much less affected by the suppressed back scattering (vertex
correction). Moreover, in the presence of roughness ferromagnetic resonance
under a \textit{uniform} microwave field can gennerate a considerable amount of
surface magnons.
