The difference between stud link and studless chain comes down to a single component: the stud. In a stud-link chain, every common link carries a crossbar — the stud — across its middle. In a studless chain, the links are plain, open rings with no crossbar. The presence or absence of a stud identifies the structure; it does not establish the grade or complete geometry. Manufacturer catalogues describe stud-link chain for large ocean-going vessels, while Ramnäs Offshore also lists studless chain in its mooring-chain range. Studless is not simply a lower-quality version of stud-link chain.[1][2] This article explains what the stud does, why link structure and strength grade are separate ideas, how the two designs differ in application, and what to check before treating one as a substitute for the other.
What the stud actually does
Stud-link chain is described in manufacturers' catalogues as cross-braced on each link to provide increased strength and resistance to crushing. The crossbar holds the two sides of the link apart, so the stud resists the oval link being flattened or crushed when the cable is loaded. The stud braces the link; it is not a guarantee against deformation at any load. It is worth keeping that description at the level of structure rather than turning it into a general performance ranking — a stud changes how a link is built, not what grade it is.[1]
Link structure is not the same as grade
ISO 1704:2022 is the standard for stud-link anchor chains, and it groups its chain under several grades. The important point for this article is simply that several grades exist within one structural type. "Stud link" and "studless" describe how a link is made; a grade describes a strength level. A studded link is therefore not automatically a higher grade, and a studless link is not automatically a lower one. Grade values and grading systems are a separate subject and are not repeated here.[4]
Comparing the two designs
| Aspect | Stud-link chain | Studless chain |
|---|---|---|
| Link structure | Each common link has a crossbar (stud) bracing it open | Plain open links, no crossbar |
| Structure vs. grade | Two independent dimensions: a stud is not a grade designation | Likewise independent of grade |
| Application context | Described for large ocean-going vessel anchor cables in the cited manufacturer catalogue | Offered for offshore mooring in the cited Ramnäs product range; not an automatic ship-chain substitute |
| Geometry and deck equipment | Defined by nominal diameter plus stud-link geometry | Different link geometry — windlass gypsy, stopper and connecting parts must match the actual design |
| Defect awareness | Loose or missing studs are an in-service defect handled under class survey | No stud to loosen; the chain still has its own applicable inspection requirements |
A common misconception: studless is not "small-boat only"
Studless chain should not be defined as suitable only for small boats or low-strength work. Ramnäs Offshore publishes studless chain within its offshore mooring-chain range.[2] That product scope is a concrete counterexample to the small-boat-only claim, not a universal performance comparison. The stud/no-stud choice is not a quality ladder.
It is also worth being precise about context. Ramnäs describes offshore mooring as a different duty from the more intermittent use of ship anchor chain.[2] This article stays with the merchant temporary-anchoring case and does not carry offshore selection rules over to it.
A missing stud is not a studless chain
Two things can look similar but must not be confused: a common link that has lost its stud, and a link that was designed without one.
IACS Rec. 79 (2003/Rev.1, 2014), Guidance for Anchoring Equipment in Service, treats loose or missing studs as defects to be handled under survey. It states that during the Special Survey Hull, when the anchor cable is ranged, gauged and examined, there should be no looseness of studs within links; where loose studs exist, the affected cable should be replaced, or where considered feasible, welded in accordance with an approved procedure; and where studs are missing, the affected lengths should be replaced. Securing a loose stud by welding must first be submitted to the surveyor for evaluation and approval. On that basis, the loss of a stud is a defect that is handled through the applicable inspection and approval route — it does not convert a stud-link cable into a compliant studless design. Repair procedures and their parameters are outside the scope of this article.[3]
Separately, a deliberately studless link is a normal part of some stud-link arrangements. Fountom's chain catalogue notes that the studless End Link is designed to accept components such as anchor shackles, and IACS Rec. 79's design note likewise refers to end studless links in outboard end swivel pieces. So a purpose-designed open end link is an ordinary part of a stud-link connection arrangement, and is entirely different from a common link that has simply lost its stud.[1][3]
What to check before substituting one for the other
- Confirm the actual chain design, not just the diameter. Nominal diameter alone does not describe the whole geometry: Ramnäs, for example, publishes a studless link narrower than its stud-link of the same nominal diameter, so two chains of the same nominal size are not therefore interchangeable. This is one supplier's documented difference, not a universal ratio.[2]
- Match the deck equipment to the specific chain. Windlass gypsy (chain wheel), chain stopper and connecting parts should be checked against the specific chain drawing or specification before use.
- Ask for the full description. Chain type, grade and the matching components should be confirmed against the documentation for the vessel and the equipment.
Where to go next
Browse the stud link anchor chain and studless anchor chain categories, or review the wider anchor chain range. If you are comparing the two designs for a specific vessel, the practical next step is to confirm the required chain type, grade and matching deck equipment, then contact the team.
References
[1] Fountom, Deck Machinery — Anchor Chain, “General Information” and “Stud Link Components”: https://www.fountom.com/service_warranty/downloads/Fountom_Anchor_Chain.pdf
[2] Ramnäs Offshore AB, Studless product page (supplier-specific geometry and offshore mooring product scope): https://ramnas.com/products/mooring-chains/studless/ ; History (ship-chain versus offshore duty context): https://ramnas.com/company/history/
[3] IACS, Recommendation No. 79 — Guidance for Anchoring Equipment in Service, Rev.1 (2014), Sections 4–5 and Annex: https://iacs.s3.af-south-1.amazonaws.com/wp-content/uploads/2022/05/20151746/rec_79_pdf219.pdf
[4] ISO 1704:2022, Ships and marine technology — Stud-link anchor chains, Clause 6, public preview (not the complete standard): https://cdn.standards.iteh.ai/samples/77746/bf35a8e6871a4fcaabbef575f43d1dab/ISO-1704-2022.pdf
