Martyr CMKK2Z Zinc Keel Anode | 3-1/4” x 3-1/4” x 1-1/8” | Saltwater
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Martyr Zinc Keel Anode — CMKK2Z | Saltwater
A zinc-alloy sacrificial keel anode designed for hull-mounted corrosion protection on sailboats and powerboats operating in saltwater. This anode bolts directly to the keel or hull and sacrifices itself to protect surrounding underwater metal fittings, through-hulls, and structural hardware from galvanic corrosion.
Zinc is the traditional choice for saltwater environments. If you operate in freshwater, a magnesium alloy anode is the correct choice for that water type.
Part Information
- Part Number: CMKK2Z
- Brand: Martyr Anodes
- Anode Material: Zinc
- Anode Type: Keel / Hull-Mount Anode
- Best Use: Saltwater environments
Dimensions
- Length: 3-1/4” (82.5 mm)
- Width: 3-1/4” (82.5 mm)
- Height: 1-1/8” (28.6 mm)
Compatible Applications
- Hull-mounted keel anode position on sailboats and powerboats
- Suitable for steel, aluminum, and fiberglass hulls with metal underwater fittings
- Saltwater operating environments
Installation Notes
Mount flush to the hull or keel using the existing bolt pattern. Ensure full metal-to-metal contact between the anode base and the hull fitting for effective electrical bonding — paint or coating between the anode and hull surface will prevent the anode from working. Inspect the bonding wire connection if your vessel uses a bonding system.
Service Interval
Inspect keel anodes at every haulout and replace when worn to approximately 50% of original size. In high-galvanic marina environments or areas with significant stray current, anodes may deplete faster than expected — inspect more frequently if you notice accelerated wear.
Parts Desk Insights
Keel anodes are one of the most straightforward anode replacements on the boat, but the most common issue we see is improper installation — specifically, paint or antifouling coating applied over the anode face or between the anode and the hull. An anode that isn’t making direct metal contact isn’t protecting anything. The second most common issue is choosing the wrong alloy: zinc in freshwater won’t corrode fast enough to do its job. If your boat lives on a freshwater lake, use a magnesium anode instead. For saltwater and coastal use, zinc is a reliable and cost-effective choice for this position.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.