Martyr CMC04 Zinc Limited Clearance Shaft Anode – Stainless Allen Screw | Saltwater
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Martyr Zinc Limited Clearance Shaft Anode — CMC04 | Saltwater
A zinc sacrificial shaft anode designed for propeller shaft installations where a standard round anode won’t fit due to tight clearances near the hull, strut, or cutlass bearing. The CMC04 is part of the Martyr CMC limited clearance series and is sized for a specific shaft diameter range — confirm your shaft diameter against the CMC series specifications before ordering. Secured with a stainless steel Allen head screw for a clean, tool-accessible installation.
Zinc is the traditional choice for saltwater environments. If you operate in freshwater, a magnesium alloy shaft anode is the correct choice for that water type.
Part Information
- Part Number: CMC04
- Brand: Martyr Anodes
- Anode Material: Zinc
- Anode Type: Limited Clearance Shaft Anode
- Fastener: Stainless steel Allen head screw
- Best Use: Saltwater environments with tight shaft clearances
Compatible Applications
- Propeller shafts with limited clearance to hull, strut, or cutlass bearing
- Inboard and shaft-drive installations where standard round shaft anodes will not fit
- Confirm shaft diameter compatibility before ordering
- Saltwater operating environments
CMC Series — Choosing the Right Size
- CMC01 — lightest limited clearance shaft anode (~150 g)
- CMC02 — mid-size limited clearance shaft anode (380 g)
- CMC03 — larger limited clearance shaft anode (585 g)
- CMC04 (this part) — limited clearance shaft anode (551 g) — confirm shaft diameter before ordering
Related Shaft Anodes
- Aluminum Streamline Shaft Anode 1” — CMT-X03AL — streamline profile for reduced drag
- Zinc Streamline Shaft Anode 1-1/2” — CMT-X07 — streamline zinc shaft anode
- Zinc Shaft Anode 4” — CMT-X17 — larger zinc shaft anode
- Zinc Shaft Anode MDX-5 1-1/4” — standard profile zinc shaft anode
- Zinc Shaft Anode MDX-7 1-1/2” — standard profile zinc shaft anode
Service Interval
Inspect shaft anodes at every haulout and replace when worn to approximately 50% of original size. Shaft anodes can deplete faster than hull or drive anodes due to their direct exposure on the rotating shaft — inspect more frequently on vessels kept in high-galvanic marina environments.
Parts Desk Insights
The CMC series covers multiple shaft diameter ranges in the same limited clearance profile — the most important step before ordering any CMC anode is confirming your exact shaft diameter and available clearance. The CMC04 sits between CMC02 and CMC03 in mass, which may indicate it covers a specific shaft diameter or metric size not addressed by the other units in the series. If you have the space for a standard round profile, a full-round anode provides more sacrificial mass and longer service life between replacements. 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.