Thone1,
On the particular model in the recent pictures, and no doubt others would be similar, there is a Corrosion and Erosion Control Guide (CECG) manual.
In addition some of the manufacturers have woken up to the fact that superyachts are a form of free advertising (envy, endorsement of the product etc etc blah blah).
Subsequently there are additional measures that can be optionally introduced at manufacture. ECD for instance offer complete internal painting of the frame with polyurethane before assembly as one example.