Shackles for Marine Applications

Why are there so many shackles and what are they used for – how to select the right shackle for my mooring chains.

Shackles are essential components in marine mooring and lifting operations, serving as critical connectors between various rigging elements. At EYE Marine, we offer a diverse range of shackles designed to meet the rigorous demands of maritime environments. Below is an overview of the types of shackles we provide, their specific applications, the significance of pin colour coding, material considerations, and the effects of corrosion in saltwater settings.

Types of Shackles and Their Applications

1. Square Head Dee Shackle This shackle features a D-shaped design with a square head pin, providing a secure connection for in-line loads. It’s commonly used in lifting operations where the load direction is predictable and consistent.
2. Blue Pin Screw Bow Shackle Characterised by a larger, rounded bow and a screw pin with a blue coating, this shackle allows for multi-directional loading. It’s ideal for marine mooring applications where angles may vary, offering flexibility and ease of use.
3. Blue Pin Safety Bow Shackle Similar to the screw bow shackle but equipped with a safety bolt and cotter pin, this design ensures the pin remains secure under dynamic or vibrating conditions. It’s suitable for critical lifting and mooring tasks requiring enhanced security.
4. Forelock Shackle Featuring a forelock pin secured by a split ring, this shackle is often used in permanent or long-term installations. Its design prevents accidental loosening, making it reliable for static mooring setups.
5. Stainless Steel Safety Bow Shackle Made from corrosion-resistant stainless steel, this shackle includes a safety mechanism to prevent pin rotation. It’s ideal for marine environments where exposure to saltwater is a concern, ensuring longevity and reliability.
6. Stainless Steel Bow Shackle A simple bow shackle crafted from stainless steel, suitable for general-purpose mooring and lifting applications. Its corrosion resistance makes it a preferred choice in marine settings.
7. Stainless Steel 316 Counter Sunk Shackle Manufactured from high-grade 316 stainless steel with a countersunk pin, this shackle offers a smooth profile, reducing snagging risks. It’s commonly used in applications where aesthetics and minimal obstruction are important.
8. Stainless Steel Dee Shackle This D-shaped shackle made from stainless steel is suitable for in-line loads in lifting and mooring operations. Its corrosion resistance ensures durability in harsh marine environments.
9. Galvanised Commercial Bow Shackle Featuring a galvanised coating to resist rust, this bow shackle is suitable for general marine applications. It’s a cost-effective option for non-critical mooring and lifting tasks.
10. Galvanised Commercial Dee Shackle A D-shaped shackle with a galvanised finish, ideal for straightforward, in-line load applications in marine settings. It’s commonly used in less demanding environments where budget considerations are important.
11. Green Pin Wide Mouth Safety Bow Shackle This shackle boasts a wider mouth and a green pin, allowing for connections with larger components. The safety bolt ensures secure usage in heavy-duty lifting and mooring operations.
12. Green Pin Safety Bow Shackle Featuring a standard bow with a green safety pin, this shackle is versatile for various marine applications, offering reliability and ease of inspection.

             All of our shackles are listed HERE

Pin Colour Significance

The colour of a shackle’s pin often indicates specific characteristics or standards:

• Green Pin: Typically signifies that the shackle has been individually tested and meets stringent quality standards. This colour coding is widely recognised in the industry as a mark of reliability.
• Blue Pin: Indicates batch testing, where a sample from the production batch has been tested for compliance. While still reliable, it’s essential to ensure that the shackle meets the necessary specifications for critical applications.
• Other Colours: Manufacturers may use various colours for branding or identification purposes. It’s crucial to refer to the manufacturer’s documentation to understand the specific meaning of pin colours, as there is no universal standard.

Materials, Applications, and Limitations

• Galvanised Steel: Offers a protective zinc coating to resist rust and corrosion. Suitable for general marine applications; however, over time, the galvanised layer can wear off, especially in abrasive conditions, reducing its effectiveness.
• Stainless Steel (e.g., 316 Grade): Provides superior corrosion resistance, making it ideal for harsh marine environments with prolonged saltwater exposure. It’s more expensive but offers longevity and reduced maintenance.
• Alloy Steel: Known for high strength and durability, alloy steel shackles are suitable for heavy lifting operations. However, they may require protective coatings to prevent corrosion in marine settings.

Corrosion and Saltwater Effects

In marine environments, shackles are continually exposed to saltwater, oxygen, and varying temperatures, all contributing to corrosion:

• Galvanic Corrosion: Occurs when dissimilar metals are in contact in the presence of an electrolyte like saltwater, leading to accelerated deterioration. Selecting shackles and pins made from similar materials can mitigate this effect.
• Pitting and Crevice Corrosion: Stainless steel, while resistant to general corrosion, can suffer from pitting in chloride-rich environments. Regular inspection and maintenance are essential to identify and address such issues early.
• Protective Measures: Regular cleaning, application of anti-corrosion coatings, and cathodic protection are strategies to extend the lifespan of shackles in marine settings.

Please call us for advice and support for the trade supply of any of the items on our website.