5/16" Stainless Steel Lock Washer – Marine Grade Hardware EZ LoaderBoat Trailers 290-002635-S

This 5/16" stainless steel lock washer is a high-quality, corrosion-resistant fastener designed for EZ Loader boat trailers, aluminum trailers, and a wide range of marine and outdoor applications. Built from durable stainless steel, this lock washer provides long-term protection against vibration, road shock, and hardware loosening—a common issue on trailers that see regular highway travel or launch-ramp use.

Engineered with a split-ring design, the washer compresses as the nut tightens, creating consistent tension that helps prevent fasteners from backing off under load. This makes it ideal for hardware assemblies such as bunk brackets, guide-on uprights, winch stands, fender mounts, and axle or frame accessories found on modern EZ Loader or aftermarket marine trailers.

Key Features

5/16" size — fits standard 5/16" stainless or galvanized bolts and nuts

Marine-grade stainless steel — excellent resistance to rust, corrosion, and saltwater exposure

Split lock design — provides spring tension to help keep hardware secure under vibration

Ideal for marine trailers — commonly used on EZ Loader bunk brackets, winch posts, fenders, and support hardware

High-strength construction — maintains clamping force on rough roads, long-distance towing, and high-vibration environments

Compatible with aluminum and galvanized components — reduces risk of galvanic reaction when paired with stainless fasteners

Common Trailer Applications

EZ Loader bunk bracket assemblies

Guide-pole mounting hardware

Trailer winch stands & bow stops

Pontoon trailer hardware

Fender brackets & step plates

General marine and utility trailer fastening

Why Choose Stainless Steel?

Stainless steel is the preferred metal for marine environments because it resists rust, oxidation, and chemical wear far better than standard steel or zinc hardware. When combined with stainless bolts and nylock nuts, this lock washer helps maintain a secure, long-lasting connection that stands up to repeated launching, towing, and seasonal storage.

Specifications

Material: Marine-grade stainless steel (304 or 316 depending on supply)

Size: 5/16"

Type: Split lock washer

Compatibility: Stainless, galvanized, and aluminum trailer assemblies