Sea Dog Eye Nuts Investment Cast 316 Stainless Steel

How They Work

These threaded eye nuts are designed to screw onto bolts or lengths of threaded rod stock. This simple approach allows you to accommodate varying material thicknesses—such as different transom widths—by selecting the appropriate bolt length. Once tightened, the eye nut creates a strong, closed-loop attachment point suitable for lines, shackles, or snap hooks.

Built from 316 Stainless Steel

Constructed from investment cast 316 stainless steel, these eye nuts offer superior corrosion resistance compared to 304 grade or zinc-plated alternatives. The 316 alloy contains molybdenum, which provides enhanced protection against pitting and crevice corrosion—particularly important for boats operating in saltwater along Canada's Atlantic and Pacific coasts. Investment casting produces a dense, uniform grain structure that resists fatigue and stress cracking over time.

Installation Considerations

Installation is straightforward: simply thread the eye nut onto a bolt or threaded rod of the matching diameter and pitch. For through-bolted applications, ensure the bolt extends far enough to allow full thread engagement. Use a flat washer and backing plate on the opposite side for maximum holding strength, particularly when fastening through fibreglass or wood. Apply a marine-grade anti-seize compound to the threads to prevent galling and make future removal easier—especially important for Canadian boaters who may need to disassemble hardware for winter storage.

Specifications

• Material: Investment Cast 316 Stainless Steel
• Thread Type: National Coarse (NC)
• Size Option 1 (SKU #31713): 1/4"-20 NC Thread
• Size Option 1 — Dimension B: 7/16"
• Size Option 1 — Dimension C: 1-1/4"
• Size Option 1 — Dimension D: 5/8"
• Size Option 1 — Dimension E: 3/16"
• Size Option 1 — MFG Part#: 078106
• Size Option 2 (SKU #31714): 5/16"-18 NC Thread
• Size Option 2 — Dimension B: 9/16"
• Size Option 2 — Dimension C: 1-1/2"
• Size Option 2 — Dimension D: 13/16"
• Size Option 2 — Dimension E: 1/4"
• Size Option 2 — MFG Part#: 078108
• Size Option 3 (SKU #31715): 3/8"-16 NC Thread
• Size Option 3 — Dimension B: 5/8"
• Size Option 3 — Dimension C: 1-7/8"
• Size Option 3 — Dimension D: 1"
• Size Option 3 — Dimension E: 5/16"
• Size Option 3 — MFG Part#: 078110

Key Features 

• Investment cast construction — delivers a smooth, precise finish with consistent structural integrity
• 316 stainless steel alloy — resists pitting and crevice corrosion in saltwater environments
• Threads onto standard bolts or rod stock — accommodates varying transom or material thicknesses
• Versatile securement point — suitable for tie-downs, lifting eyes, and line attachment
• Three NC thread sizes available — matches common marine bolt diameters for easy sourcing