Marine Propeller Lock Set Featuring Three Quarter Inch 16 Thread Locking Nut With Free Spinning Collar For Mercury MerCruiser And OMC, Replaces 74039, Easy Install, Durable Marine Boat Prop Shaft Locking System For Outboard Engines

3/4-16 Marine Propeller Lock Set - Single Lock with Collar
✔️ Includes 1 lock, 1 key, 1 washer, 1 cap; 3/4-16 compatible

This marine propeller lock set replaces the standard propeller nut with a locking nut that features a free-spinning collar. It’s designed for harsh saltwater environments and is compatible with Mercury, MerCruiser, and OMC engines that use a 3/4-16 thread.

✅ Thread Size: 3/4-16
✅ Hex Size: 1-1/16
✅ Overall Length: 1.025 in
✅ Locking System: Replaces standard nut with free-spinning collar
✅ Includes: Set with 1 Lock, 1 Key, 1 Washer, 1 Cap
✅ Material: Brass and hardened stainless steel for marine corrosion resistance
✅ Compatibility: Mercury, MerCruiser, OMC 3/4-16; replaces 74039; not OE 74040

💡 What is a propeller lock set used for and how does it help boat owners?

It’s a handy security accessory that protects the propeller from theft and tampering while docked or stored, and is easy to install.

Security: Theft protection for propellers in marinas and docks
Installation: Easy to install with included key and basic tools
Performance: Secure fit without affecting propeller operation
Materials: Brass and hardened stainless steel resist corrosion in saltwater