Making an iron hull last on distant stations

A ship sent far from dockyards had to resist marine growth without allowing dissimilar metals to accelerate corrosion through its iron or steel hull. Copper sheathing controlled fouling on wooden ships, but placing it directly against iron created a damaging electrolytic reaction. Chief Constructor Nathaniel Barnaby's solution wrapped the lower hull in two substantial timber layers before adding the copper, with one timber layer continuing higher above the waterline. The wood isolated the metals and also contributed useful protection over the hull structure. The arrangement made the ships heavy and dense, but it reduced cleaning demands and made sustained foreign-station service practical.