Type A vs. Type B Swivel Shackles vs. Swivel Forerunner: What’s the Difference?

Introduction: Lessons from a Real Inquiry

Recently, we received an inquiry from an old client that simply read: "Need Type B Swivel." We instantly knew this client understood their vessel's configuration perfectly. However, for many buyers and engineers, distinguishing between Type A, Type B, and the traditional Swivel Forerunner （often also referred to as a Swivel Assembly）can be confusing. Choosing the wrong model doesn't just mean it won't fit—it can introduce serious safety hazards. Today, we are going to clarify the design and application of these three components. 

 1. Concept Breakdown: What Exactly Are They? 

Traditional Swivel Forerunner (Swivel Assembly): A composite transition piece. It typically features an end shackle  on one side and a standard chain link on the other. It cannot replace the anchor shackle and must be used in conjunction with it.Type A Swivel Shackle: An integrated design. Its design philosophy is to replace the anchor shackle. It connects directly to the anchor shank and the chain, significantly shortening the connection distance.

Type B Swivel Shackle: Also an integrated design, but its philosophy is to replace the end shackle. It works in conjunction with a standard anchor shackle, sitting between the anchor shackle and the chain. 

 2. Connection Methods: How Are They Installed? 

Traditional Setup: Anchor → Anchor Shackle → Swivel Forerunner → Kenter Shackle → Chain. (Highest number of connection points)

Type A Setup: Anchor Shank → Type A Swivel Shackle → End Link → Chain. (Eliminates the anchor shackle)

Type B Setup: Anchor → Anchor Shackle → Type B Swivel Shackle → End Link → Chain. (Retains the anchor shackle, eliminates the extra end shackle)

3. Why Do Type A and Type B Look So Different? 

Although both are integrated swivel shackles, their design philosophies result in drastically different sizes and load-bearing characteristics: 

Type A (Heavy-Duty Integrated): Its mission is to directly replace the anchor shackle and bear the direct pulling force of the anchor shank. Therefore, it has an extremely robust and bulky structure. It places high demands on the hawse pipe dimensions and the windlass's load-bearing capacity.

Type B (Lightweight Integrated): Used in conjunction with an anchor shackle, it replaces the original end shackle. It features a more compact design and is the most standard, universal configuration for the vast majority of commercial vessels.

Swivel Forerunner: A composite design with a longer overall structure. 

What this means for you: If deck space is limited or the windlass hasn't been upgraded, Type B is the most practical and safest choice (which is exactly why our old client specifically requested it). Only when designing a highly compact anchor system would an engineer choose Type A. 

 4. Standards & Certification: What Really Matters? 

Historically, the dimensions and design of swivel shackles have referenced various national shipbuilding standards. However, in today's international marine procurement, the most critical benchmark is classification society certification (CCS, ABS, LR, DNV, etc.). As long as the product holds a class society Type Approval and has passed proof load testing, it is recognized for use on large vessels globally. 

 5. Installation Advice & A Fatal Mistake to Avoid 

For safety, we strongly recommend installing all swivel shackles strictly according to the vessel's original design drawings. If your drawings are lost, our technical team can provide accurate installation guidance. 

There is one critical detail that can never be overlooked: whether it's Type A, Type B, or a Kenter Shackle, once the main pin is inserted, the taper pin must be driven in and sealed with a lead plug. In our after-sales experience, many failures are not due to material breakage, but installation negligence where the lead plug was skipped. The lead plug is the final mechanical safeguard preventing the pin from backing out under vibration. Skip this step, and the pin can easily work loose, causing the swivel to open at sea. (Internal Link: Want to know how to inspect lead plugs properly? Read our guide: Kenter Shackle Lead Plug Failure.) 

 6. Selection Guide: Which One Do You Need? 

For Standard, Universal Configuration: If the anchor already has a shackle and you don't want to change the setup, Type B is the most reliable choice. (This is exactly why our client specified Type B).

For Extreme Compactness: If you want to save space in the hawse pipe, Type A replaces the anchor shackle directly, allowing the anchor to stow more easily.

For Traditional Setups: If the chain ends with a standard link, the Swivel Forerunner remains a proven classic. 

 Conclusion:

Not sure which type fits your vessel? Send us your anchor shank dimensions and end link specifications. Our technical sales team will confirm the most suitable model and size, complete with full class society certification. SMEOCEAN — Your expert partner for anchor chain systems.

More Links:

End Shackle vs Joining Shackle: What's the Difference and Why It Matters

Anchor Chain Accessories: A Complete Guide

Why Swivel Forerunner is a Transformative Design？