Sierra Prop Nut 18-3726, Replaces OE 09141-18005, Brass

The Sierra 18-3726 Prop Nut secures the propeller onto the propeller shaft of an outboard motor, providing a durable, precision-machined fastening point that meets or exceeds original equipment quality. Machined from brass, this prop nut resists corrosion in the marine environment while standing up to the torque loads placed on the propeller during operation. It features a hex head with a Unified National Coarse thread in a 12mm (M12) size, fully threaded with a right-hand thread direction and a Class 3A thread fit for reliable engagement on the shaft. The nut carries a machined exterior finish and is built to Sierra's industrial grade rating, making it a direct fit replacement for the original equipment part it is designed to replace. This is a compact, single-piece hardware item, sold individually, and is intended for boat owners and marine technicians performing propeller installation, removal, or maintenance. Because it directly replaces OE part number 09141-18005, it installs using the same thread engagement and torque specifications as the original hardware, with no modification required. Keep a spare on hand whenever servicing your propeller, since prop nuts should be inspected for thread wear or damage each time the propeller is removed.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3726
• Product Name: Prop Nut
• Material: Brass
• Fastener Type: Prop Nut
• Thread Size: 12mm (M12)
• Thread Type: Unified National Coarse
• Thread Style: Right Hand
• Thread Coverage: Fully Threaded
• Thread Class: Class 3A
• Screw Head Style: Hex
• Drive Style: Hex
• Compatible Groove Diameter: 12 millimeters
• Grade Rating: Industrial
• Exterior Finish: Machined
• Color: White
• Item Dimensions: 0.39 x 0.39 x 0.39 inches
• Weight: 0.13 pounds
• Number of Pieces: 1

Replaces (OEM)

• 09141-18005

Frequently Asked Questions

What does the Sierra 18-3726 Prop Nut replace? The Sierra 18-3726 Prop Nut directly replaces OEM part number 09141-18005, so it installs as a drop-in equivalent using the same thread engagement as the original nut.

What material is the 18-3726 prop nut made from? It is machined from brass, a material chosen for its corrosion resistance in marine environments and its ability to hold up under the torque loads placed on a propeller nut.

What thread size does this prop nut use? The 18-3726 uses a 12mm (M12) Unified National Coarse thread, fully threaded, with a right-hand thread direction and a Class 3A thread fit.

How much does the Sierra 18-3726 weigh? This prop nut weighs 0.13 pounds.

What are the dimensions of the 18-3726 prop nut? Item dimensions are 0.39 x 0.39 x 0.39 inches, consistent with a compact single hex prop nut.

Does the Sierra 18-3726 meet OEM quality standards? Yes, Sierra manufactures the 18-3726 Prop Nut to meet or exceed the original equipment part it replaces, part number 09141-18005.

How many prop nuts come in one purchase? One Sierra 18-3726 Prop Nut is included per purchase; it is sold as a single piece, not a kit.

What color and finish does the 18-3726 prop nut have? The 18-3726 has a machined exterior finish and is white in color.

Is the 18-3726 a hex nut? Yes, the Sierra 18-3726 Prop Nut has a hex head and hex drive style for use with a standard wrench or socket.

When should I replace my outboard's prop nut? Inspect the prop nut, such as the Sierra 18-3726, whenever the propeller is removed, and replace it if the threads show wear or damage since a worn nut can loosen under load.

What grade rating does the Sierra 18-3726 carry? Sierra rates the 18-3726 Prop Nut as industrial grade.