Galvanic Isolators and Their Importance on Narrowboats
Protecting your narrowboat from the silent menace of corrosion is crucial, especially when hooked to shore power. Learn about galvanic isolators and how this essential device shields your boat from potential damage, ensuring both longevity and safety
What is a Galvanic Isolator?
A galvanic isolator is a device used to block low-voltage DC currents that are usually under 1.2 volts, while still allowing AC currents to pass. These DC currents, if unchecked, can lead to a process called “galvanic corrosion.” This type of corrosion can damage underwater metal parts of boats, such as propellers, shafts, and hull fittings when they are connected to shore power.
The principle behind a galvanic isolator is quite simple: it takes advantage of the diode’s properties. Diodes are components that allow current to flow in only one direction, and they require a certain voltage (called the “forward voltage”) to start conducting. By using diodes in series, a galvanic isolator creates a voltage threshold below which current won’t flow. This threshold is typically set above the range of galvanic voltages but below the harmful stray current levels.
Why is Galvanic Corrosion a Concern?
When two different metals come into contact with an electrolyte (like the water in which a boat floats), a galvanic cell can be created. This is the same principle that batteries operate on. The more dissimilar the metals, the stronger the electrical potential difference between them. One metal will act as an anode and corrode, while the other will act as a cathode and be protected.
For boats, especially those made of steel, like many narrowboats, this poses a significant problem. If a steel-hulled boat is moored next to another vessel made of a more noble metal, like stainless steel or bronze for example, the steel boat can act as the anode and suffer corrosion, whereas the other vessel remains unaffected.
Why are Galvanic Isolators Important for Narrowboats?
- Material Construction: Narrowboats are commonly made of steel, making them particularly vulnerable to galvanic corrosion. When connected to shore power, the boat’s metal can become part of a larger galvanic cell with neighbouring boats or metal structures in the water.
- Close Proximity Mooring: Narrowboats are often moored in close proximity to other vessels in marinas or along canals. This closeness increases the risk of forming galvanic cells with neighbouring boats.
- Protection of Equipment: Corrosion due to galvanic action can damage crucial components of the boat, leading to expensive repairs or replacements. This includes the hull, which can be extremely costly to repair.
- Extended Lifespan: By reducing or eliminating the effects of galvanic corrosion, a galvanic isolator can significantly extend the lifespan of a narrowboat and maintain its structural integrity.
- Cost-Effective: While there might be an upfront cost to install a galvanic isolator, the long-term savings from preventing potential damage or replacement of parts is substantial. If you intend to spend a lot of time in a marina then get the best you can afford.
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Watch the Video Below to Learn How to Install this Type of Galvanic Isolator
Are plug-in galvanic isolators any good?
Plug-in galvanic isolators are designed to provide a simpler and more convenient way to protect boats from galvanic corrosion, especially for boat owners who may be hesitant about more invasive installations. They are designed to plug directly into the shore power connection, making them easy to install and use.
Here are the pros and cons of plug-in isolators:
Pros:
- Ease of Installation: Plug-in isolators are straightforward to install, often requiring no tools or technical knowledge. This ease can be especially appealing to those who aren’t comfortable with electrical installations.
- Portability: Their plug-and-play nature means they can be easily moved between boats, making them ideal for boaters who rent or switch vessels regularly.
Cons:
- Durability: Due to their design, plug-in isolators might not be as robust or long-lasting as their hardwired counterparts.
- Limited Protection: Some plug-in models might not offer the same comprehensive protection as more traditional galvanic isolators. It’s essential to research and choose a reputable brand/model.
- Potential for Disconnection: The plug-in nature means there’s a risk of accidental disconnection, especially in rough conditions or high-traffic docking areas.
- Not Universal: Not all plug-in isolators will fit every shore power plug type or configuration. It’s important to ensure compatibility before purchase.
Plug-in galvanic isolators can be a good option for those looking for a simple, cost-effective solution, especially if they’re not planning to rely on it for extended periods or in particularly high-risk areas. However, for more permanent or comprehensive protection, a traditional hardwired galvanic isolator might be a better choice. Always research specific brands and models to ensure you’re getting a reliable and effective product.
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Do I need to use a galvanic isolator as a continuous cruiser?
Suppose you never connect to shore power and don’t spend time in marinas close to other boats that are connected to shore power. In that case, the risk of galvanic corrosion from external sources is significantly reduced. In such a scenario, a galvanic isolator is not needed.
While the risk of galvanic corrosion from external sources might be low, boats can still experience other forms of corrosion, like stray current corrosion, which originates from electrical faults within the boat itself. A galvanic isolator won’t protect against this type of corrosion, but it’s worth being aware of and regularly checking for.
Conclusion
Galvanic isolators are crucial devices for any boat owner, but they’re especially essential for narrowboats due to their typical construction material and mooring conditions. Investing in a galvanic isolator is not only a wise financial decision but also crucial for the safety and longevity of the vessel. If you own or are considering purchasing a narrowboat, it’s highly recommended to ensure it’s equipped with a quality galvanic isolator to protect against the insidious effects of galvanic corrosion.
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