Shop sacrificial anodes for all types of marine engines.

All marine engines and underwater metals on boats are subject to galvanic corrosion — which if not prevented can result in expensive damage. To protect inboard engines, outboard motors and underwater metal parts against galvanic corrosion, West Marine offers a wide variety of sacrificial anodes to meet the needs of a wide variety of applications.

What is galvanic corrosion?

Galvanic corrosion is the process that leads to the breakdown of metals immersed in an electrolyte such as salt water. When dissimilar electrically connected metals are immersed (creating a galvanic cell) a current is generated which destroys the least noble of the two metals (the anode). Many people wrongly refer to this process as electrolysis.

Using an outboard motor as an example, when the lower unit is immersed in water, its aluminum case becomes anodic to other metal parts such as the motor’s stainless steel prop shaft, fasteners or oil drain plug. In the ensuing galvanic reaction, the aluminum case sacrifices itself to the more noble metal parts. Evidence of this can be seen in the pitting of the aluminum case.

How do anodes work?

Continuing with the outboard example above, sacrificial anodes take the place of the motor’s aluminum case as the least noble (more reactive) metal component of the assembly. As the least noble metal component, they sustain the galvanic reaction, thus saving the casing of the motor. For anodes to be effective, they should never be painted. We also suggest that anodes be changed when the galvanic reaction has reduced their mass by 50 percent.

Types of Anodes Offered by West Marine

As mentioned above, West Marine offers sacrificial anodes for a wide variety of applications on a boat. Types of anodes offered include inboard engine anodes, outboard anodes, sterndrive anodes and prop nut anodes. Anodes are offered for other applications, including heat exchangers, water heaters and air conditioning units.

Anode Kits

While owners of outboard or inboard/outboard motors can purchase anodes individually, purchasing anodes as a kit greatly simplifies the shopping experience. Anode kits contain all the anodes that are required for specific models of outboard or inboard/outboard motors. Kits are sold under the Martyr brand and they are available for most brands of outboard and inboard/outboard motors, including Mercury, MerCruiser, Volvo-Penta, Evinrude, Tohatsu, Yamaha and more.

Anode Materials

It has been shown that anode performance can vary with the type of water (salt, brackish, fresh) where a boat is used and the material of which the anode is made. For this reason, anodes are offered with a choice of materials — zinc for saltwater, aluminum for salt or brackish water and magnesium for freshwater.

Available Anode Brands

Brands of anodes available at West Marine include Martyr, Sea Shield and Sierra.