Zinc Rudder Anode 5″ CMT-R04

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Alternate / Superseded Part Numbers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 isnt just cosmeticit helps reduce drag while still giving full protection coverage.

Shipping

Shipping: Ships same or next day for fast Canada wide shipping.