Shop transom anodes at West Marine.

The sacrificial transom anodes found on this page are specifically designed to protect inboard/outboard and outboard lower units against damage due to galvanic corrosion. In addition to what you see here, West Marine offers other types of anodes which are often bolted on to the stern (aka transom) of boats. These include plate, teardrop and other styles of anodes which you will find by browsing to Hull Anodes.

What is the purpose of sacrificial anodes?

Sacrificial anodes protect boats against damage due to galvanic corrosion. Galvanic corrosion can occur whenever dissimilar metals are connected together in an electrolyte such as seawater. In the case of outdrive lower units, this can be the stainless steel bolts that hold an aluminum outdrive together. Left unprotected, the aluminum casing will become anodic to the bolts and suffer damage due to galvanic corrosion. To guard against this, anodes are installed which "sacrifice" themselves and corrode in place of the aluminum casing.

Anode Materials

West Marine offers sacrificial zinc, aluminum and magnesium anodes. When selecting anodes it is important to choose anodes that are made of the material that works best in the type of water where you use your boat.

Zinc Anodes: If you use your boat in salt water, zinc anodes are a good choice.

Aluminum Anodes: Provide protection in salt water or brackish water.

Magnesium Anodes: These are your best choice if you use your boat in fresh water.

Monitor the condition of your anodes.

To ensure continued protection, it is important to periodically inspect, and when needed, replace your anodes. We suggest that you replace your anodes when they are 50 percent gone. The relatively small cost of a set of anodes is nothing when compared to the cost of repairing or replacing a damaged outboard or inboard/outboard lower unit.