Zinc Alloy welded type hull sacrificial anodes; place a metal ship in the sea, and you have a giant battery, with the resultant loss of metal to the sea; to prevent such damage to the ship, and costly repairs, sacrificial metal blocks are either bolted and bonded, or welded to the hulls. Each one around 25 pounds in weight, 16 of them here just delivered to Apache, some will be needed on the underhull surface. Any offers?
This is old science, as when timber ships plied the oceans, boring creatures enjoyed the scrummy wet timbers, so metal sheets were placed over the timbers, copper ('copper bottomed') as a security against holes, but all manner of problems ensued, either with plants and animals, as well as the rusting of nails (which ended up with sheets of copper dropping off into the sea), so yellow metal (brass rich in zinc) began to be used, as well as adding felt as a separating layer ... resulting in greater accumulator action. The sacrificial anode came into being, as a concentration node for the discharge of material.