Martyr CMM24 Zinc Hull Anode | 4.36” x 1.92” x 0.7” | Bolt-On | Saltwater

Martyr Zinc Hull Anode — CMM24 | Saltwater

A compact bolt-on zinc hull anode for saltwater use. The CMM24 mounts flush to the hull using its pre-drilled bolt hole pattern and provides sacrificial galvanic protection for the surrounding hull structure, through-hulls, and underwater metal fittings. Its smaller footprint makes it well suited for targeted anode placement on steel, aluminum, or fiberglass hulls where a full-size plate anode is not required.

Zinc is the traditional choice for saltwater environments. If you operate in freshwater, a magnesium alloy hull anode is the correct choice for that water type.

Part Information

• Part Number: CMM24
• Brand: Martyr Anodes
• Anode Material: Zinc
• Anode Type: Bolt-On Hull Anode
• Best Use: Saltwater environments

Dimensions

• Length: 4.36” (110.7 mm)
• Width: 1.92” (48.8 mm)
• Height: 0.7” (17.8 mm)
• Note: Hole dimension refers to the distance between mounting holes — confirm bolt pattern against your hull fitting before ordering

Compatible Applications

• Steel, aluminum, and fiberglass hull installations — bolt-on hull anode position
• Targeted anode placement where a full-size plate anode is not required
• Saltwater operating environments

Installation Notes

Mount flush to the hull using the pre-drilled bolt holes. Ensure full metal-to-metal contact between the anode base and the hull fitting — paint or antifouling coating between the anode and hull surface will prevent the anode from working. If your vessel uses a bonding system, inspect the bonding wire connection at the same time.

Related Hull Anodes

• Martyr CMDIVERZ Zinc Hull Plate Anode – ½” x 6” x 12” — larger zinc hull plate anode
• Martyr CMDIVERHZ Heavy Zinc Hull Plate Anode – 1” x 6” x 12” — heavy-duty zinc hull plate
• Martyr CMDIVERMINI Zinc Mini Hull Plate Anode – 6” x 4” x ½” — compact zinc hull plate anode
• Martyr CMDIVERA Aluminum Hull Plate Anode – ½” x 6” x 12” — aluminum option for saltwater and brackish water
• Martyr CMDIVERM Magnesium Hull Plate Anode – ½” x 6” x 12” — magnesium option for freshwater

Service Interval

Inspect hull 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, inspect more frequently as depletion rates can vary considerably.

Parts Desk Insights

The CMM24 is a good choice for targeted hull anode placement — particularly on steel or aluminum hulls where you need to protect a specific area without covering a large surface. The most important installation detail is ensuring the anode base makes direct metal contact with the hull: any paint, coating, or sealant between the anode and the hull surface will electrically isolate it and render it ineffective. For broader hull protection or larger vessels, the full-size CMDIVERZ zinc plate anode provides significantly more sacrificial mass and longer service life between replacements. If your boat operates in freshwater, switch to a magnesium alloy anode — zinc won’t corrode fast enough in low-conductivity water to provide meaningful protection.