Zinc Rudder Anode 5" CMT-R04
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
The CMT-R04 is a 5" zinc rudder anode (R-4 style) designed to protect rudders and trim tabs from galvanic corrosion in saltwater environments. This dome-shaped anode mounts directly to the rudder or trim tab and sacrifices itself to prevent corrosion of critical underwater metals.
Manufactured from high-purity zinc alloy, it provides reliable and consistent protection for inboard vessels.
Key Features
- 5" diameter disc-style rudder anode
- Marine-grade zinc (saltwater optimized)
- Dome profile for reduced drag
- Bolt-on design with stainless hardware
- Meets or exceeds MIL-spec corrosion standards
- Designed for long-lasting sacrificial protection
Application / Compatibility
Designed for:
- Rudders
- Trim tabs
- Flat underwater surfaces
✔ Common on:
- Inboard boats
- Cruisers and sportfish vessels
- Sailboats
✔ Protects:
- Rudder plates
- Trim tabs
- Adjacent bonded underwater metals
Serial Number Fitment Notice
Always confirm:
- Diameter (5")
- Thickness (~5/8")
- Mounting hardware style and thread
Correct fit ensures proper electrical contact and protection.
When This Part Needs Replacement
- Anode is 50% or more consumed
- Uneven wear or pitting
- Loss of material thickness
- Routine haul-out inspection
Installation Notes
- Install on clean, bare metal surface
- Ensure tight, even mounting
- Do not paint the anode
- Inspect hardware regularly
- Replace before full depletion
Alternate / Superseded Part Numbers
- Camp Company: CMT-R04
- Martyr: CMR04
- Aluminum version: CMT-R04AL
- Magnesium version available for freshwater
Parts Desk Insight
This 5" size is one of the most common rudder/trim tab anodes. The dome shape isn’t just cosmetic—it helps reduce drag while still giving full protection coverage.
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.