Swivel Forerunner Assembly
As a key component connecting segmented anchor chains and anchor fittings, the OLIPORTS swivel forerunner features an industry-standard 3-link or 4-link design that allows for 360-degree free rotation, effectively preventing the anchor chain from twisting and knotting and extending the equipment’s service life. Our products are manufactured in strict compliance with ISO 1704 standards, undergo comprehensive load testing and quality verification, and are suitable for mooring systems on various types of vessels, dredging projects, and offshore platforms.
With over 15 years of experience in manufacturing marine mooring equipment, OLIPORTS boasts an engineering team certified by IACS classification societies. All swivel forerunner products undergo third-party independent testing to ensure reliable performance in even the harshest marine environments.
What is A Swivel Forerunner In A Ship’s Anchor Chain System?
A swivel forerunner (also known as a swivel short chain section) is a special composite short chain segment located between the anchor and the main anchor chain. Its primary function is to prevent twisting. When a vessel rotates due to wind, waves, and currents, the swivel forerunner can rotate freely through 360°, thereby dissipating torsional forces and preventing dangerous twisting and knotting of the chain. This ensures that the anchor chain passes smoothly through the windlass sprocket during anchoring and weighing operations.
Technical Features of Swivel Forerunners
| Features | Standard & Specifications |
|---|---|
| Type | 3-link; 4-link; multi-link swivel forerunners |
| Grade | Grade 2 & 3 |
| Nominal Diameter | 12.5mm to 162mm |
| Material | alloy steel/carbon steel/stainless steel |
| Surface finishing | black painting/hot dip galvanized/electro-galvanized |
| Certificate | DNV-GL, BV, LRS, ABS, IRS, RS, KR, NK, CCS |
| Tags: | anchor chain connector; mooring chain accessories; anchor chain swivel forerunner |
Anatomy of a Standard Swivel Forerunner
The standard OLIPORTS swivel forerunner is assembled from high-tensile chain links in a scientifically optimized sequence, typically in an E + EL + SW + EL + C configuration, to bridge the anchor and the main anchor chain:
End Link (E Link): The frontmost open-link chain link with a larger internal space, specifically designed to accommodate the D-ring end shackle directly connected to the anchor handle.
Enlarged Link (EL Link): A link one size larger than a standard link, serving as a smooth transition in strength and size between the end link and the swivel.
Swivel (SW Link / Swivel): The mechanical core of the entire swivel assembly, precision-forged to ensure 360-degree free rotation even under maximum tensile loads.
Standard Link (C Link / Common Link): The final standard link in the chain, which connects seamlessly to the main anchor chain via a Kenter shackle.
3-Link, 4-Link & Multi-Link Swivel Forerunners Assembly
To accommodate different ship designs, anchor winch configurations, and marine mooring requirements, OLIPORTS offers three distinct swivel assembly systems:
| Configuration | Structural Design | Best Applications |
|---|---|---|
| 3-Link Swivel Forerunner Assembly | Consists of an extended link + swivel + extended link (EL+SW+EL). Compact design | Suitable for compact anchor chain drums and small vessels with limited space for counter-rotating ring assemblies. |
| 4-Link Swivel Forerunner Assembly | Includes an end link + extended link + swivel + extended link (E+EL+SW+EL). | The industry standard for commercial ocean-going cargo ships, offering excellent flexibility and easy connection to standard D-rings. |
| Multi-Link Forerunner Swivel Assembly | Custom-made according to specific blueprints, including additional standard links or multiple swivels. | Specifically designed for heavy-duty offshore oil platforms, permanent mooring buoys, and deep-sea exploration vessels operating in complex, multi-directional currents. |
OLIPORTS offers customized heavy-duty swivel forerunner solutions tailored to chain diameter, working load, vessel type, and offshore operating conditions.
Swivel Forerunner Selection Guide by Chain Diameter
| Diameter (mm) | Common Link (kg) | Enlarged Link(kg) | Open End Link (kg) | Swivel (kg) | L (mm) | GR3 Proof Load (kN) | GR3 Prpf Load (kN) | GR2 Breaking Load (kN) | GR3 Breaking Load (kN) |
|---|---|---|---|---|---|---|---|---|---|
| 12.5 | 0.17 | 0.23 | 0.23 | 0.9 | 350 | 65.7 | 92.2 | 92.2 | 132 |
| 14 | 0.24 | 0.32 | 0.36 | 1.3 | 392 | 82.4 | 110 | 116 | 165 |
| 22 | 0.93 | 1.25 | 1.28 | 3.5 | 616 | 200 | 280 | 280 | 401 |
| 30 | 2.4 | 3.2 | 3.3 | 9.0 | 840 | 368 | 514 | 540 | 735 |
| 38 | 4.7 | 6.1 | 6.8 | 19.0 | 1064 | 581 | 812 | 812 | 1160 |
| 40 | 5.5 | 7.1 | 9.8 | 23.0 | 1120 | 640 | 896 | 896 | 1280 |
| 56 | 16 | 21 | 23 | 67 | 1568 | 1220 | 1710 | 1710 | 2430 |
| 60 | 19 | 25 | 27 | 95 | 1680 | 1380 | 1940 | 1940 | 2770 |
| 73 | 34 | 45 | 52 | 172 | 2044 | 1990 | 2800 | 2800 | 3990 |
| 90 | 64 | 82 | 95 | 300 | 2520 | 2920 | 4090 | 4090 | 5840 |
| 111 | 120 | 160 | 175 | 535 | 3108 | 4250 | 5940 | 5940 | 8480 |
| 132 | 205 | 260 | 305 | 760 | 3696 | 5720 | 8000 | 8000 | 11420 |
| 147 | 2800 | 395 | 410 | 1200 | 4116 | 6840 | 6560 | 9560 | 13660 |
| 162 | 375 | 500 | 560 | 1700 | 4536 | 7990 | 11170 | 11170 | 15970 |
The data presented in the table above represents only a selection of specifications for Type B Swivel Shackles. OLIPORTS can provide additional sizes, breaking loads, custom designs, and the Marine Swivel Shackle Technical Data Sheet based on your anchor chain system requirements. Please feel free to contact our team for complete specifications and engineering support.
