Marine Hardware

Stainless Steel Shackles

Marine-grade 316L stainless steel shackles from Profab Machine. They are built for rigging, mooring, lifting, and offshore applications where corrosion resistance and documented load ratings are non-negotiable. Available in bow, D/chain, and twisted types with screw-pin or safety-pin closure.

Shackles Supplier

Stainless Steel Shackles Manufacturer in China

A stainless steel shackle is a U-shaped connector closed by a removable pin, used to link ropes, chains, wire rope, and structural hardware at load-bearing joints. In marine and rigging applications, shackles are the primary interface between anchor chains, mooring lines, sails, deck fittings, and structural pad eyes. The pin design allows the connection to be made or broken without cutting any line.

Galvanised shackles lose their zinc coating in seawater within three to five years. The exposed base steel then corrodes, reducing the actual cross-section below the stamped WLL — with no visible warning before failure. 316L stainless maintains full material dimensions indefinitely in salt water. Its 2–3% molybdenum content raises the Pitting Resistance Equivalent Number (PREN) to ≥ 24, providing the chloride resistance that galvanised hardware cannot match.

Product Range

Types of Stainless Steel Boat Shackles

Profab supplies four standard cleat configurations in 316 stainless. Each style addresses specific deck layout and loading requirements. Custom profiles are available on request.

Bow / Anchor Shackle

The bow shackle has a rounded, wider bow that distributes force across the inside radius regardless of load direction. It handles side loads up to 50% of WLL and accepts multiple lines simultaneously without cross-loading the pin. Use a bow shackle for anchor systems, mooring buoy chains, towing, and any connection where the load direction can change during operation.

D / Chain Shackle

The D shackle has straight, narrow sides optimised for inline tension only — no more than one component per end, no side loads. Testing shows that a 45° side load reduces effective WLL to as low as 30% of the rated value. Use D shackles exclusively for direct chain-to-chain joins or shackle-to-eye connections in standing rigging where the load axis is fixed and predictable.

Twisted / Dee Shackle

The body of a twisted shackle rotates 90° so the pin and bow lie in perpendicular planes. This lets you connect two components whose axes are at right angles — for example, a turnbuckle jaw to a chainplate running athwartship — without forcing a bending load onto the pin. Specifying the correct twisted shackle at these junction points significantly extends the fatigue life of the rigging assembly.

Safety Pin (Bolt-and-Nut) Shackle

Safety pin shackles replace the standard screw pin with a captive bolt-and-nut closure that cannot shake loose under vibration or cyclic loading. They are mandatory for overhead lifting applications, offshore crane work, and any permanent installation not subject to regular inspection. Available in both bow and D body profiles. CE marking with individual proof-load test certificates (2× WLL) supplied on request.

Material Specification

304, 316L, or 17-4PH — Matching Grade to Environment

304 Stainless

The standard austenitic grade for bushings in non-marine, non-chemical environments. Excellent machinability allows tight bore tolerances at competitive cost. Suitable for food equipment, automation, and indoor industrial applications.

Food · Automation · Indoor

316 / 316L

The specified grade for bushings in salt spray, seawater, and chloride-rich environments. The 2–3% molybdenum addition raises pitting resistance equivalent number (PREN) to ≥ 24 — well above the 304 threshold. Essential for marine fittings, valves, pump trims, and outdoor installations. Especially 316 stainless steel has excellent resistance to corrosive saltwater effects.

Marine · Chemical · Pumps

17-4PH

Precipitation-hardened martensitic grade achieving ≥ 1,310 MPa tensile strength in H900 condition. Specified for bushings in high-load, small-envelope applications where a 304 or 316L bushing would be too large to achieve the required load capacity. Used in aerospace, motorsport, and precision industrial machinery.

Aerospace · Motorsport · Hi-load

Applications

Where Stainless Steel Marine Shackles Are Used

Sailboat Standing Rigging

D shackles on shroud-to-chainplate connections and bow shackles on forestay attachment. Twisted shackles at chainplate-to-turnbuckle junctions where perpendicular geometry would otherwise create pin-bending moments. 316L body is required for any standing rigging on salt-water vessels.

Anchor and Mooring Systems

Bow shackles join anchor chain to anchor crown and swivel at both ends. Safety-pin variants are specified for permanent mooring buoy chains that are not regularly inspected. The bolt-and-nut pin cannot rotate loose under the cyclic loading from wave action.

Offshore Platform and Subsea

Duplex 2205 shackles for platform mooring lines, riser hang-off points, and ROV umbilical connections where 316L stress-corrosion cracking resistance is marginal at operating temperatures.

Commercial Shipping and Cargo Lashing

Safety-pin bow shackles for cargo lashing, deck-mounted pad eye connections, and container handling equipment on commercial vessels and ro-ro ferries.

Commercial Fishing and Aquaculture

316L bow shackles for net hauling, trawl gear connections, and aquaculture cage mooring systems. Stainless maintains full cross-section over its service life in seawater, eliminating the 3–5 year replacement cycle required with galvanised hardware.

Water Sports and Rescue Equipment

Lightweight M6–M12 316L shackles for kite-surfing harnesses, wakeboard tower connections, and coast-guard rescue equipment where both corrosion resistance and minimum weight are simultaneously required.

Why Profab

Precision Machined to Your Exact Specification

Direct-from-Manufacturer Advantage

We are the original manufacturer—eliminate all unnecessary middlemen. That means you get the most competitive prices in the market. Enjoy maximum profit margins while ensuring consistent, high-quality stainless steel parts tailored for your business.

Engineering Support and Fast Sampling

We work closely with your technical team to understand and respond to your unique part needs. Whether it’s a CAD file, material conversion or specific tolerances, we can quickly provide samples and provide expert feedback to accelerate your product development.

Volume Discounts for Scalable Business

The more you order, the more you save. We offer tiered pricing for bulk orders, helping you stay competitive as you scale your business. Enjoy more flexible terms for long-term partnerships.

Technical Reference

WLL Reference Table

Table —Working Load Limits by Pin Size (316L Bow Shackle, Screw Pin, Static Axial Load)

Pin Size (Metric)	Pin Size (Imperial)	WLL (kg)	WLL (lbs)	MBL (kg)	Approx. Weight
M6	1/4″	300	660	1,500	35 g
M8	5/16″	500	1,100	2,500	65 g
M10	3/8″	700	1,540	3,500	110 g
M12	7/16″	1,000	2,200	5,000	170 g
M14	1/2″	1,200	2,640	6,000	250 g
M16	5/8″	2,000	4,400	10,000	420 g
M20	3/4″	3,200	7,040	16,000	750 g
M24	1″	4,750	10,450	23,750	1.4 kg
M30	1-1/4″	8,500	18,700	42,500	3.2 kg
M36	1-1/2″	12,000	26,400	60,000	6.0 kg
M40	—	17,000	37,400	85,000	9.5 kg
M52	2″	25,000	55,000	125,000	22 kg

FAQ

Common Questions

Not seeing your question? Email us at [email protected] and we typically reply same day.

What is the difference between a bow shackle and a D shackle?

A bow (anchor) shackle has a rounded, wider bow that allows side loading and can accept multiple lines simultaneously. A D (chain) shackle has a straight, narrow body designed exclusively for inline tension — no more than one component per end, zero side load. Side-loading a D shackle at just 45° can reduce effective load capacity to around 30% of the rated WLL. When the load direction can vary or multiple lines share one point, always specify a bow shackle.

Can I use these shackles for overhead lifting?

Yes, but you must specify the safety-pin version and request CE marking at time of order. CE-marked shackles are individually proof-load tested to 2× WLL and supplied with a Declaration of Conformity for compliance with EU Machinery Directive 2006/42/EC. Standard screw-pin shackles are rated and marketed for marine rigging and mooring — not overhead lifting per the directive. Specify your intended use at enquiry and we will recommend and document the correct product.

Is Duplex 2205 available, and when should I specify it?

Yes, Duplex 2205 shackles are available in M10–M40 on enquiry. Specify Duplex when you need a smaller, lighter shackle at the same WLL as a 316L version — Duplex 2205 has approximately 30% higher yield strength at equivalent cross-section. Also specify Duplex for subsea, tropical seawater (above 25°C), or any application where stress-corrosion cracking in austenitic 316L is a documented concern. Duplex 2205 carries a PREN of 34–36 versus 316L’s ≥ 24.

Complete Your Assembly

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