Regularly replacing the Lewmar bow thruster zinc anode is essential to protect your boat’s propulsion system from galvanic corrosion. If you're wondering how to safely change the zinc underwater without dry docking, this guide will show you how — even if you're doing it for the first time.
🔍 Why Replacing the Zinc Is Important
Zinc anodes protect your metal components by corroding first — a process called sacrificial protection. When your zinc wears out, your thruster’s motor housing and blades can become vulnerable to expensive damage.
🧰 Tools and Equipment You’ll Need
- New Lewmar-compatible zinc anode
- Snorkeling or dive gear (with weight belt)
- Underwater-safe wrench or socket set
- Thread locker or marine-grade sealant (optional)
- Wire brush or sandpaper (to clean contact area)
- Diving safety buddy (recommended)
⚙️ How to Change the Zinc Underwater
- Inspect the current anode: If more than 50% of the zinc is eroded, it’s time to replace.
- Clean the mounting surface: Use a wire brush to remove buildup and ensure clean metal contact.
- Remove the old anode: Use an underwater wrench to unscrew the corroded zinc.
- Apply thread locker: Prevents vibration-related loosening (optional but recommended).
- Install the new zinc: Tighten securely without overtightening. Double-check fit and contact with metal.
- Inspect after a test run: Check for any movement or improper contact after the thruster is used.
💡 Pro Tips
- Always keep a spare anode on board for emergency replacements
- Check zinc condition every 3 months, especially in saltwater conditions
- If diving in murky water, use a waterproof light or headlamp
📦 Shop OEM Lewmar Zinc Anodes
Get the right fit for your thruster system. Browse our Lewmar zinc replacement parts and keep your bow thruster fully protected.