Aluminum Bolt-On Round Plate Anode 4" x 1" CMT-RP4A
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The CMT-RP4A is a 4" diameter aluminum bolt-on round plate anode designed to provide reliable corrosion protection for hulls and underwater metal components. This compact disc-style anode mounts directly to the hull, protecting surrounding metals by acting as a sacrificial element.
Constructed from marine-grade aluminum alloy, it delivers longer life and more efficient protection than zinc, especially in saltwater and brackish conditions. Aluminum anodes are widely used due to their slow consumption rate and effectiveness across multiple water types.
Key Features
- 4" diameter x 1" thick round plate anode
- Bolt-on mounting design
- Marine-grade aluminum alloy construction
- Suitable for saltwater, brackish, and freshwater use
- Longer lifespan vs zinc
- Compact, low-profile protection
Application / Compatibility
Designed for:
- Hull protection
- Trim tabs
- Transoms and underwater fittings
✔ Common on:
- Inboard and outboard boats
- Aluminum and fiberglass hull vessels
- Areas requiring localized corrosion protection
✔ Typically installed near:
- Propellers
- Running gear
- Bonded metal systems
Serial Number Fitment Notice
Always confirm:
- Mounting hole spacing and bolt size
- Available surface area for installation
- Compatibility with bonding system
Correct placement is critical for effective corrosion protection.
When This Part Needs Replacement
- Anode is 50% or more consumed
- Uneven or accelerated wear
- Reduced corrosion protection
- Routine haul-out inspection
Installation Notes
- Mount to clean, bare metal surface
- Ensure solid electrical contact
- Do not paint the anode
- Use proper marine-grade fasteners
- Position to avoid disrupting water flow
Alternate / Superseded Part Numbers
- Camp Company: CMT-RP4A
- Martyr: CMRP4A
- Zinc equivalent available
- Magnesium version available for freshwater
Parts Desk Insight
Round plate anodes are ideal for targeted protection zones. Aluminum versions are now the go-to—they last longer and perform better across mixed water conditions compared to zinc, making them a strong default recommendation.
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.
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.