Martyr CMX02M Magnesium Streamline Shaft Anode – 7/8” Shaft | Stainless Allen Screw | Freshwater
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Martyr Magnesium Streamline Shaft Anode — 7/8” Shaft | CMX02M | Freshwater
A 7/8-inch magnesium streamline sacrificial shaft anode for inboard propeller shafts in freshwater environments. The streamline (teardrop) profile reduces hydrodynamic drag compared to a standard round shaft anode, making it a preferred choice for performance-conscious inboard installations. Secured with a stainless steel Allen head screw for a clean, tool-accessible installation.
Magnesium is the correct alloy for freshwater use — zinc and aluminum anodes are too electrochemically passive in low-conductivity water to provide adequate protection. If you operate in saltwater or brackish water, see the aluminum and zinc alternatives linked below.
Part Information
- Part Number: CMX02M
- Brand: Martyr Anodes
- Anode Material: Magnesium
- Anode Type: Streamline Shaft Anode
- Shaft Diameter: 7/8”
- Fastener: Stainless steel Allen head screw
- Best Use: Freshwater environments
Compatible Applications
- 7/8” propeller shafts — inboard and shaft-drive installations
- Applications where reduced hydrodynamic drag is preferred over a standard round anode
- Freshwater operating environments only
Choosing the Right Alloy — 7/8” Streamline
- Magnesium (this part) — Freshwater use only
- Aluminum — CMX02AL — Saltwater and brackish water; best all-around choice for mixed conditions
- Zinc — CMX02 — Saltwater use
Related Streamline Shaft Anodes — Other Sizes
- Aluminum Streamline Shaft Anode 1” — CMT-X03AL
- Aluminum Streamline Shaft Anode 1-1/8” — CMT-X04AL
- Zinc Streamline Shaft Anode 1-1/2” — CMT-X07
- Martyr CMX12 Zinc Streamline Shaft Anode – Large Diameter
- Martyr CMX13 Zinc Streamline Shaft Anode – Large Diameter
Service Interval
Inspect shaft anodes at every haulout and replace when worn to approximately 50% of original size. Magnesium anodes in freshwater deplete at a moderate rate — inspect annually and replace promptly to maintain continuous protection on the shaft and surrounding hardware.
Parts Desk Insights
The CMX02M is the correct choice for 7/8” streamline shaft anodes on freshwater inboard installations — the most common mistake we see is customers installing zinc anodes in freshwater lakes, where zinc doesn’t corrode fast enough to provide meaningful protection. The streamline profile sheds water cleanly and creates less turbulence than a round anode at speed, with a minor trade-off in sacrificial mass. If your boat moves between fresh and salt water, the aluminum CMX02AL is the more versatile option. Always confirm the anode has solid metal-to-metal contact with the shaft — a loose fit or painted shaft surface will prevent the anode from working.
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.