What is stray current corrosion, and how can it differ from ordinary galvanic corrosion?

A. Stray current corrosion is identical to galvanic corrosion in every respect

B. Stray current corrosion is driven by an external electrical fault (often shore power wiring, a faulty appliance, or a marina's own wiring) rather than the boat's own dissimilar metals — it can be far more aggressive and rapid than natural galvanic corrosion, and can affect a well-bonded, well-anoded boat that would otherwise be protected

C. Stray current corrosion only occurs on boats that have never been connected to shore power

D. Stray current corrosion is a myth with no real electrochemical basis

A. Marine electrical components are actually more resistant to corrosion than automotive ones

B. The combination of salt air, humidity, and vibration accelerates corrosion at electrical connections far faster than in a typical land environment — a loose or corroded connection can cause intermittent faults, voltage drop, or complete failure right when equipment is needed most

C. Corrosion only affects the battery casing itself, never the terminals or connections

D. This is only a concern for boats kept permanently in salt water, never for boats on a mooring or in a marina

A. Galvanic corrosion only occurs above the waterline, so anodes are purely decorative

B. When two dissimilar metals are both immersed in an electrolyte like seawater and electrically connected, a small current flows and the more reactive metal corrodes preferentially — a sacrificial anode is deliberately made of an even more reactive metal so it corrodes first, protecting the more valuable fittings (propeller, shaft, skin fittings) instead

C. Galvanic corrosion is entirely prevented simply by using stainless steel fittings throughout

D. Anodes are fitted only to prevent osmosis in GRP hulls