Martyr CMT-Z04AA Aluminum Hull Anode with Aluminum Strap – 6" x 3-1/2" x 1"
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Martyr CMT-Z04AA Aluminum Hull Anode with Aluminum Strap – 6" × 3-1/2" × 1"
| Part Number | CMT-Z04AA |
| Brand | Martyr Anodes |
| Official Part Type | Hull Anode with Aluminum Strap |
| Zinc Equivalent | CMT-Z04ZA (zinc strap version) |
| Material | Aluminum alloy anode body / Aluminum strap |
| Dimensions | 6" × 3-1/2" × 1" (152 × 89 × 25 mm) |
| Weight | ~0.55 kg / ~1.2 lb |
| System | Hull-mounted galvanic corrosion protection |
| Suitable Waters | Saltwater and brackish water |
What This Anode Does
The Martyr CMT-Z04AA is an aluminum hull anode with an integrated aluminum mounting strap. It protects hull-mounted systems and bonded underwater metals from galvanic corrosion by sacrificing itself in place of more critical metal components. The aluminum strap maintains full metal-to-metal electrical continuity between the anode and the hull bonding system, and avoids the mixed-metal concerns that can arise when a zinc or steel strap is used with an aluminum anode.
Aluminum anodes are the preferred choice for saltwater and brackish water and outperform zinc in most real-world marine environments due to their more electronegative potential and longer service life.
Compatible Applications
- Hull-mounted corrosion protection on inboard and sterndrive vessels
- Trim tab and transom areas
- Bonded underwater metal systems
- Vessels operating in saltwater or brackish water
- Installations where full aluminum compatibility is required
Related Products
Fitment Notice
Before ordering, confirm:
- Mounting hole spacing on the strap matches your hull fitting location
- Clearance on the hull mounting surface for the 6" × 3-1/2" footprint
- Compatibility with your vessel’s bonding system
- The CMT-Z04ZA is the zinc-strap version of this same anode — confirm which strap material your installation requires
When to Replace
- Anode body is 50% or more consumed
- Uneven wear, heavy pitting, or loss of structural integrity
- Loss of bonding contact or continuity between anode and strap
- Routine replacement at each haul-out
Installation Notes
- Mount on a clean, bare metal surface free of paint or coatings
- Do not paint or antifoul over the anode body — it must remain exposed to the water to work
- Ensure firm electrical contact between strap, fasteners, and hull bonding
- Tighten mounting hardware securely but do not overtorque into aluminum strap
- Inspect the bonding system if wear is uneven across the anode surface
Service Interval
Inspect at every haul-out. Replace when the anode is 50% consumed or shows uneven wear. In high-current environments or vessels with active corrosion issues, inspect more frequently. Do not wait until the anode is fully depleted before replacing.
Technical FAQ
Why choose aluminum over zinc for this anode?
Aluminum anodes are more electronegative than zinc in saltwater, which means they provide stronger galvanic protection and last longer. In brackish water, zinc anodes can passivate (form an oxide layer that stops them from corroding properly), while aluminum remains active. For most saltwater and brackish installations, aluminum is the better choice.
What is the difference between CMT-Z04AA and CMT-Z04ZA?
Both are the same hull anode body in the same 6" × 3-1/2" × 1" size. The CMT-Z04AA uses an aluminum strap; the CMT-Z04ZA uses a zinc strap. The aluminum strap version eliminates mixed-metal contact at the mounting point and is preferred where full aluminum compatibility is a concern.
Can I use this anode in freshwater?
Aluminum anodes are not recommended for freshwater. In freshwater, magnesium anodes are the correct choice. Confirm your operating environment before selecting anode material.
Should I use thread sealant on the mounting fasteners?
Do not use thread sealants or coatings that would create an electrical barrier between the strap and the hull surface. Electrical continuity at the mounting point is essential for the anode to function correctly.
Parts Desk Insights
The CMT-Z04AA comes up most often when a customer wants to stay fully aluminum throughout the anode installation — aluminum body, aluminum strap, aluminum fasteners — to avoid any mixed-metal contact at the mounting point. That matters on aluminum-hulled vessels and on GRP hulls where the bonding system runs through aluminum fittings. The most common issue is painting over the anode by accident during bottom paint application — once the anode is coated, it stops working. Tape it off or remove it before painting and reinstall after.
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.