Nautical Electrolysis

Also known as electrolytic corrosion or galvanic corrosion, nautical electrolysis is a process where metal parts of a vessel corrode due to electrical currents in the water. This occurs when different metals in contact with water create an electrochemical reaction, leading to the deterioration of the less noble (more reactive) metal.

Causes of Nautical Electrolysis

• Dissimilar Metals in Contact
  • When two different metals (e.g., aluminum and stainless steel) are in contact in a conductive environment (like seawater), a galvanic cell forms, leading to corrosion of the more reactive metal.
• Stray Electrical Currents
  • Leaking electrical currents from a boat’s electrical system or nearby marina power sources can accelerate corrosion. These stray currents flow through the water and interact with submerged metal components.
• Saltwater as an Electrolyte
  • Seawater is a strong conductor, speeding up electrolysis and making boats more susceptible to corrosion compared to freshwater environments.

Effects of Nautical Electrolysis

• Corrosion of Propellers, Shafts, and Hulls – Metal parts like propellers, rudders, and hull fittings deteriorate over time.
• Damage to Marina Infrastructure – Metal docks, piers, and underwater structures can suffer damage from stray currents.
• Increased Maintenance Costs – Without proper prevention, repairs and replacements can be expensive.

Prevention & Protection

• Sacrificial Anodes (Zinc, Aluminum, or Magnesium Anodes) – These anodes corrode instead of the boat’s key components, protecting them from electrolysis.
• Proper Electrical Grounding – Ensuring a well-grounded electrical system can prevent stray currents from flowing through metal parts.
• Isolating Dissimilar Metals – Using plastic washers or coatings to prevent metal-to-metal contact can reduce galvanic reactions.
• Electrolysis Testers & Monitoring – Regularly checking for stray currents and electrolysis levels helps catch issues early.