Compolysis: How It Works

Boaters know how electrical currents remove particles of metal from one underwater fitting and deposit them on another. A bronze prop can be coated with aluminum removed from a neighboring sterndrive. In that “system,” the aluminum sterndrive is the anode and loses electrons (and particles) to the cathode, the bronze prop.

Similarly, compolysis attacks cored fiberglass laminates, like submerged boat hulls. As the electrical potential increases, one skin becomes anodic and releases electrons to the other skin, the cathode, to balance the system. Particles detach from one skin and land on the other, making the cored laminate much weaker than its designers intended. For more details, watch the video below that outlines the causes of, and fixes for, compolysis.