Knowledge Centre

Your trusted source for practical marine corrosion advice.

Learn from the experts. Access technical guides, product information, FAQs, videos, and tools to help you make informed decisions about protecting your vessel from corrosion.

Corrosion Explained

New to marine corrosion? Learn the fundamentals of marine corrosion.

  • Galvanic Corrosion is an electrochemical reaction that causes electrons to flow from one metal to another metal, within the same electrolyte. The more active metal (anode) will deplete and essentially electroplate the more passive metal (cathode) with the anode material to achieve parity. A sacrificial anode is introduced into a combination of metals in order to provide the most active metal to protect all others.

  • Electrolysis is broadly referred to as an electrical influence causing a reaction between an anode and a cathode. In the world of boats, electrolysis is generally referring to the effect of electrical stray currents on metallic components resulting in aggressive corrosion activity. This type of corrosion can bypass anode and directly cause aggressive corrosion.

  • Stray current corrosion is one of the most aggressive forms of marine corrosion. It occurs when unwanted electrical current escapes from a vessel or nearby electrical source and passes through the water, causing underwater metal components to corrode much faster than normal.

    Common signs include rapid anode consumption, severe corrosion on propellers, shafts or other underwater metals, and recurring corrosion problems. If you suspect stray current corrosion, it's important to identify and fix the source of the electrical fault rather than simply replacing damaged parts.

    Learn more in our Knowledge Centre or contact the MPS team. If a professional investigation is required, LOGIX Consulting can provide expert corrosion diagnostics and tailored solutions.

  • Cathodic Disbondment occurs when a large potential difference (voltage) occurs between the cathode (protected metal) and the anode. The high drive potential essentially drives off coatings, resulting in coating failure and high levels of marine growth. Maddox Anodes combat this problem by supplying a lower potential anode that has less potential to affect a coating.

  • Corrosion isn't always obvious, but early detection can help prevent costly damage. Common signs include excessive or uneven anode wear, pitting or discolouration on underwater metals, coating or paint failure, corrosion on propellers or shafts, and recurring corrosion problems while berthed in a marina.

    If you notice any of these signs, don't ignore them. Inspect your vessel's corrosion protection system, use our Anode Calculator to check you're using the right anode, or explore our Knowledge Centre for practical guidance. If the problem persists or you're unsure of the cause, contact MPS for product advice or LOGIX Consulting for professional corrosion diagnostics and tailored recommendations.

  • Cathodic protection is a technique used to prevent galvanic corrosion of metals, especially in marine environments. It works by making the metal that needs protection act as the cathode in an electrochemical cell, while a more easily corroded metal (the sacrificial anode) is used to absorb the corrosive effects. The sacrificial anode, such as zinc or aluminum, corrodes instead of the protected metal, thereby extending the life of structures like boat hulls or underwater pipelines.

    This method relies on the difference in voltage between metals, as described in the Galvanic Series, to ensure the anode corrodes preferentially.

Corrosion Problems & Troubleshooting

Experiencing corrosion? Start here.

  • Anodes naturally wear over time as they protect your vessel from corrosion. However, if they're disappearing unusually fast, it could indicate a more serious issue such as stray current, galvanic corrosion, incorrect anode selection, or an electrical fault.

    Regular inspections are essential to ensure your corrosion protection system is working effectively. If you're concerned about excessive anode wear, explore our Knowledge Centre, use our Anode Calculator to check you're using the right anode, or contact the MPS team for expert advice and tailored recommendations.

  • Anodes should gradually wear over time as they protect your vessel from corrosion. If they show little or no wear, they may not be providing effective protection. This can be caused by poor electrical continuity, incorrect installation, an unsuitable anode type, or other issues within the vessel's corrosion protection system.

    If your anodes aren't wearing as expected, inspect your corrosion protection system and ensure the correct anodes have been installed. If you're unsure, contact the MPS team for expert advice and tailored recommendations.

  • Propeller corrosion can be caused by galvanic corrosion, stray current corrosion, inadequate cathodic protection, incorrect anode selection, or poor electrical bonding. Left untreated, it can lead to costly repairs and reduced performance.

    Start by checking that your vessel has the correct anodes and that they're in good condition using our Anode Calculatoror Anode Selection Guide. If corrosion continues or appears severe, contact MPS for product advice or LOGIX Consulting for a professional corrosion assessment to identify the root cause and recommend the right solution.

  • Marinas can increase the risk of corrosion due to shared electrical systems, shore power connections, neighbouring vessels, and varying water conditions. If your vessel's corrosion protection system isn't correctly designed or maintained, these factors can accelerate corrosion.

    Check that your anodes are appropriate for your vessel, inspect your corrosion protection system regularly, and consider whether an MPS Electrolysis Blocker is suitable if you use shore power. If corrosion persists or you're unsure of the cause, contact MPS for product advice or LOGIX Consulting for professional corrosion diagnostics and tailored recommendations.

  • As a general guide, inspect your anodes every 3–6 months and always before and after extended trips or periods in the water. Regular inspections help ensure your corrosion protection system is working effectively and allow you to identify unusual wear before it leads to more serious problems.

    If your anodes are wearing too quickly, not wearing at all, or you're unsure whether they're providing adequate protection, use our Anode Calculator, explore the Knowledge Centre, or contact MPS for expert advice. For ongoing corrosion concerns, LOGIX Consulting can provide professional corrosion diagnostics and tailored recommendations.

  • A well-functioning corrosion protection system should provide consistent anode wear without excessive corrosion on your vessel's underwater metal components. If you notice rapid anode consumption, little or no anode wear, pitting, coating failure, or corrosion on propellers and shafts, your system may need attention.

    Regular inspections are the best way to monitor performance. If you're unsure whether your vessel is adequately protected, explore our Knowledge Centre, use our Anode Calculator, or contact MPS for product advice. For a comprehensive evaluation, LOGIX Consulting can carry out professional corrosion diagnostics and corrosion protection assessments.

Find the Right Solution

  • Choosing the right anode depends on your vessel's construction, underwater components, and operating environment. Using the correct anode is essential for effective corrosion protection and long-term performance.

    Start with our Anode Calculator for a quick recommendation, or explore our Anode Selection Guide for more detailed information. If you're unsure or your vessel has a unique setup, contact the MPS team for expert advice—we're here to help you find the right solution.

  • A Maddox™ Anode is an advanced marine anode designed to provide effective corrosion protection for vessels with stainless steel and bronze underwater components, such as shaft-driven boats and IPS systems. Instead of allowing your vessel's valuable metal components to corrode, the anode gradually sacrifices itself to help protect them.

    Use our Anode Calculator or Anode Selection Guide to find out if a Maddox™ Anode is right for your vessel. If you're unsure, contact the MPS team for expert advice and tailored recommendations.

  • The correct Maddox™ Anode size depends on your vessel's length, underwater metal components, and overall corrosion protection requirements. Choosing the right size helps ensure your vessel receives effective, long-lasting protection.

    Use our Maddox™ Sizing Calculator for a quick recommendation or refer to the Maddox™ Sizing Guide for more detailed information. If you're unsure or your vessel has a unique configuration, contact the MPS team for expert advice and tailored recommendations.

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