I have been caught out oversimplifying and withdraw the "aggressively" unreservedly. Rather too abstract and subject to misinterpretation.
The hull protection problem would be relatively simple if it only involved a steel hull, failures of protective coatings and bronze propellers under static conditions. This sadly is seldom the case as most ships carry numerous galvanic couples, some localized, some more general. This, I would imagine, would be especially so with naval vessels fitted with a complex range of equipment.
My most notable experience with de-zincification was with two coal fired steamers built in the 80's as a result of the 70's fuel crisis. (But that's another story.) The main cooling saltwater inlet valves, amongst others, eroded quite rapidly, mainly as a result of the influence of "Defcon" equipment designed to counter marine growth in cooling systems.