Hull Cleaning

Zinc Replacement

Propeller Removal / Installation

Search and Recovery

Underwater Inspections / Photography / Video Recording

Zinc Replacement

Two occurrences to be concerned with when metals are placed in water are Galvanic Corrosion and Electrolysis.

Galvanic Corrosion occurs when two dissimilar metals in contact with each other are placed in an electrolytic solution (i.e. saltwater) and form a natural battery. This will cause ions to transfer from one of the metals to the other. This corrosive exchange will weaken the metals and create irregular surfaces (pitting).

Electrolysis is the other phenomenon which occurs that can have a deleterious effect on underwater metal components. It is usually the more significant of the two. It can lead to pitting and corrosion of any metal, under certain conditions. Like Galvanic Corrosion, Electrolysis also occurs when electrons (ions) of dissimilar metals are exchanged in an electrolytic solution (i.e. saltwater). However, this phenomenon is induced by stray currents or electrical currents not following their anticipated path. The rate of electrolysis is usually much higher than that of galvanic corrosion.

When propellers, rudders, shafts, nuts, trim tabs, etc. are placed in saltwater, they will begin to corrode by either or both of these processes if not protected. Zincs installed on a vessel are considered “Sacrificial Anodes”. This is because they will sacrifice themselves (deplete / corrode) over time in order to protect other underwater metal components. Zinc is a metal which is less noble than other metals like brass. Therefore, when placed in electrical contact with a more noble metal, it will act as an anode, and give up its ions more readily than the metal it is in contact with.

Frequent zinc inspections are necessary to determine if replacement is required in order to keep the vessels components from depleting or corroding themselves. If replacement is required, Dockside Diving can supply zincs from our inventory and transport the old zincs to a recycling facility.