Martyr Zinc Duo-Prop Ring Anode Volvo Penta CMT-875821Z
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The Martyr CMT-875821Z is a zinc ring anode for select Volvo Penta Duo-Prop / DP outdrive applications. Current supplier and manufacturer references identify it as the Martyr replacement for Volvo Penta 875821, used as a ring-style corrosion anode on compatible drives.
This is a zinc anode, which makes it the correct material choice for saltwater use. Published dimensions from current listings are approximately 4-3/8 in. outside diameter, 3-5/8 in. mounting-hole center to center, with other seller references listing about 145 mm length, 29 mm height, 92 mm diameter, and 9 mm ID depending on how the part is measured. Mounting hardware is commonly listed as included.
Key Features
- Zinc sacrificial ring anode for Volvo Penta Duo-Prop / DP outdrives
- Martyr cross reference: CM875821Z
- Replaces Volvo Penta 875821
- Ring / collar style anode for drive corrosion protection
- Common published dimensions: 4-3/8 in. OD and 3-5/8 in. hole centers
- Mounting hardware commonly listed as included
- Intended for saltwater protection
Engine Compatibility
Commonly associated with Volvo Penta 280 / 290 Duo Prop and DP-style outdrive applications. Seller references specifically identify it as a DP outdrive ring zinc anode, while additional listings describe it for Volvo Penta Duo Prop 290 series saildrive / outdrive-style applications. Because older Volvo Penta drive families can have overlapping service histories and replacement parts, fitment should be confirmed against your exact drive model and serial number before ordering.
Serial Number Fitment Notice
Please confirm fitment using your Volvo Penta drive model and serial number before ordering. This is especially important on older Duo-Prop and DP drives, where prior repairs or mixed-component service history can leave a drive wearing a different anode than expected from appearance alone. The strongest supported replacement reference found for this part is 875821.
When This Part Needs Replacement
Replace this anode when it is heavily wasted, pitted, cracked, loose, or reduced enough that it is no longer providing effective sacrificial protection. Drive anodes should be inspected regularly during haul-out and service intervals, especially on boats kept in saltwater year-round.
Installation Notes
Install on a clean metal contact surface and do not paint the anode. If replacing an older worn ring anode, inspect the surrounding mounting area and hardware at the same time. Current listings commonly indicate that mounting hardware is included, but included contents should still be confirmed against your exact source listing when ordering.
Alternate / Superseded Part Numbers
- 875821
- CM875821Z
Parts Desk Insight
Ring anodes like this protect expensive drive components in an area many owners never closely inspect until corrosion has already started. Another useful detail is that this part is often grouped with older Volvo Penta 280/290 Duo-Prop families, which makes serial-number verification especially important because many of these drives have long service lives and mixed replacement histories.
Shipping
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 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.
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