My ski with a sbt cable is a dedicated surf hull. It only sees salt and then sits for months at a time. Our ocean is pretty salty on the west coast too.
Just giving another opinion on cables. I think the main thing is I that they are run correctly With no binding and hydroturf is placed in spots that they will rub hull or other things. ALOT of people run the, wrong or in binds and don't even know it or think they are doing it right.