MG Duff 875821 Volvo Penta 280 / 290 Duo Prop Ring Anode 145 mm

MG Duff CM875821 Volvo Penta 875821 280 / 290 Duo Prop Ring Anode 145 mm – Zinc / Aluminium

The MG Duff CM875821Z and CM875821A are sacrificial ring anodes for compatible Volvo Penta 280 and 290 Duo Prop sterndrives. These replacement anodes correspond to Volvo Penta OEM part number 875821 and provide galvanic corrosion protection for electrically connected underwater metallic components of the propulsion system.

Two material versions are available: zinc (CM875821Z) and aluminium (CM875821A). Both products belong to the same ring anode series, intended for compatible Volvo Penta dual-propeller drive assemblies.

The specified anode dimensions are 145 mm in length and 29 mm in height. The mounting arrangement includes two fixing holes on 92 mm centres and a specified 8 mm stud size.

The zinc CM875821Z weighs 0.58 kg. A separate weight specification for the aluminium CM875821A has not been supplied.

Technical Specifications

Available Material Variants

Both variants are supplied individually. Select the appropriate material according to the vessel's operating water conditions and Volvo Penta's corrosion protection recommendations.

Volvo Penta Duo Prop Compatibility

The MG Duff CM875821 series is listed for compatible Volvo Penta 280 and 290 Duo Prop sterndrive configurations.

These model references reflect the supplied compatibility list. The original source abbreviates several variants as A, A1, A2, B, B1, C, C1, D, D1, D2, E and G; they are grouped here under their respective DP designations for readability.

Before ordering, confirm the specific drive model and check that the original anode corresponds to Volvo Penta part number 875821.

Duo Prop Ring Anode Dimensions and Mounting

The CM875821 series features a ring-style sacrificial anode intended for the corresponding mounting position on compatible Volvo Penta Duo Prop sterndrives.

• Specified length: 145 mm
• Height: 29 mm
• Fixing holes: 2
• Fixing-hole centre distance: 92 mm
• Stud size: 8 mm

The supplied technical data does not specify a separate width or inside diameter. These measurements should be checked against the original anode or the manufacturer's technical drawing if required for installation.

Confirm the two-hole mounting arrangement and the 92 mm centre distance before selecting a replacement.

Zinc and Aluminium Sacrificial Corrosion Protection

The MG Duff CM875821 series is available in two sacrificial materials:

• Zinc – CM875821Z: Commonly used for galvanic corrosion protection in saltwater marine environments. Specified weight: 0.58 kg.
• Aluminium – CM875821A: Used in suitable marine corrosion protection systems, including saltwater and certain brackish-water conditions.

When correctly installed with suitable electrical continuity to the metallic components requiring protection, the sacrificial material corrodes preferentially, helping reduce galvanic corrosion of electrically connected underwater sterndrive components.

Select the correct material according to operating water conditions and Volvo Penta's recommendations for the specific propulsion system.

Inspection and Replacement

Inspect the Duo Prop ring anode periodically during routine sterndrive maintenance. Replace it when the sacrificial material becomes significantly depleted, damaged or no longer securely attached.

Before fitting a replacement:

• Verify Volvo Penta OEM reference 875821.
• Confirm the specific Duo Prop sterndrive model.
• Check the 145 mm length and 29 mm height.
• Verify the two mounting holes and 92 mm centre distance.
• Check the specified 8 mm stud size.
• Inspect the mounting surfaces and follow the applicable Volvo Penta installation instructions.

Part Numbers and Cross-References

• MG Duff Zinc: CM875821Z
• MG Duff Aluminium: CM875821A
• Volvo Penta OEM: 875821
• Zinc Weight: 0.58 kg
• Aluminium EAN: 0628309122676

Scope of Supply

1 × MG Duff Volvo Penta Duo Prop Ring Anode in the selected material:

• CM875821Z – Zinc; or
• CM875821A – Aluminium.

Mounting hardware inclusion is not specified in the supplied product information.