74039 Marine Propeller Lock for Mercury MerCruiser OMC 3/4 Inch 16 Thread Size

Product Overview

This marine propeller lock set replaces your standard propeller nut to deter theft and secure your propeller. It threads onto 3/4"-16 propeller shafts found on many Mercury, MerCruiser, and OMC sterndrives and outboards. Boaters needing a simple, keyed deterrent rely on this marine propeller lock set for peace of mind at the dock or on the trailer.

Key Features & Performance

• Keyed locking design prevents unauthorized propeller removal
• Precise 3/4"-16 thread pitch mates securely with factory shafts
• Hardened stainless steel components resist corrosion in salt and fresh water
• Direct replacement for the standard propeller nut—no modifications needed
• Set includes lock nut, washer, and matching installation key

Fitment & Compatibility

• Mercury and MerCruiser Alpha, Bravo, and outboard drives with 3/4"-16 propeller shaft threads
• OMC Cobra and select sterndrives with 3/4"-16 shaft thread diameter and pitch
• Any marine propeller shaft meeting the 3/4"-16 thread specification

Common Uses

• Securing stainless steel or aluminum propellers on trailered boats
• Replacing a lost or damaged propeller lock nut and key
• Wet-slipped boats exposed to opportunistic theft
• Pre-season commissioning and propeller inspection

Technical Specifications

• Part Number(s): 74039
• Thread Size: 3/4"-16
• Compatible Brands: Mercury, MerCruiser, OMC

Frequently Asked Questions

Q: Does this lock set come with a key? A: Yes, it includes the unique key required to install and remove the locking nut.

Q: Will this fit my Mercury outboard? A: If your propeller shaft has 3/4"-16 threads, this lock set threads on directly without adapters.

Product appearance and specifications may vary slightly by batch. Compatibility may vary by serial number. Verify fitment before purchase.