Zinc Propeller Nut Assembly A 1/2″-NC13 CMT-PNAZC13

Martyr CMT-PNAZC13 is a zinc propeller nut assembly designed for shaft-driven propeller applications using a 1/2″-13 NC thread. This complete zinc/brass style prop nut anode is intended to help protect the propeller nut and nearby running gear from galvanic corrosion in saltwater service. Zinc construction is intended for saltwater use only.

Key Features

• Complete propeller nut anode assembly
• 1/2″-13 NC thread specification
• Zinc anode material for saltwater use
• Brass prop nut style assembly
• Designed to provide sacrificial corrosion protection for propeller hardware and running gear

Engine Compatibility
Suitable for shaft-driven propeller applications that specifically require a propeller nut anode assembly in Pattern A with 1/2″-13 NC threading. Because prop nut anodes are pattern- and thread-specific, fitment should be confirmed by shaft thread, nut style, propeller hub clearance, and the existing anode shape before ordering.

Serial Number Fitment Notice
Fitment should be confirmed by the installed propeller nut assembly dimensions and shaft thread specification rather than engine family alone. Match the existing assembly style, thread size, and overall nut/anode pattern before purchase.

When This Part Needs Replacement
Replace when the zinc anode is heavily wasted, cracked, loose, or no longer making proper contact. As a general service rule, sacrificial anodes should be replaced before they are fully consumed. One marine catalog reference advises checking anodes regularly and replacing them when they are about 70% consumed.

Installation Notes
Install only on applications that call for a 1/2″-13 NC prop nut anode assembly. Clean mating surfaces before installation so the anode can maintain proper electrical contact. Verify propeller retention hardware, thread engagement, and clearance after installation. Zinc anodes are not recommended for freshwater use.

Alternate / Superseded Part Numbers

• PNAZC13
• CMT-PNAZC13

Parts Desk Insight
Prop nut anodes are one of the more application-specific sacrificial anodes on a boat. Matching the thread and nut pattern is just as important as matching the anode material. For boats kept in saltwater, zinc remains a common choice, while aluminum is generally preferred for many saltwater and brackish applications.

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