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How a Marine Anchor Is Certified: From Design to Marking

Before it ever reaches the bow of a ship or a yacht, a modern anchor goes through a genuine certification process — one that has far more in common with type-approving a car than with simply buying a piece of steel. The logic behind it is straightforward: set a minimum standard for safety and performance, then verify, step by step, that the design, the production process, and the individual piece all genuinely meet it.

Because this is a technical subject, throughout this article we'll often draw a parallel with the automotive world: in many respects, the way an anchor is type-approved is surprisingly similar to how a vehicle is.

In professional practice, this role is performed by the classification societies (RINA, Lloyd's Register, DNV, ABS, BV, ClassNK, and others), which apply common technical rules issued by the international association IACS (International Association of Classification Societies). For anchors, the key references are the Unified Requirements covering anchoring equipment and manufacture (UR A1 and UR W29), which are then incorporated into each individual classification society's own rules.

Players and Rules: Who Decides What

A certified anchor is the result of three levels working together:

IACS (International Association of Classification Societies): sets common minimum requirements for the design, construction, and testing of ships and their equipment, anchors included.
Classification societies: translate these requirements into their own rules, review designs, approve manufacturing facilities, and issue certificates.
Anchor manufacturers: design and produce the anchor, demonstrating compliance with the required technical and quality rules.

The parallel with the automotive world is immediate:
IACS provides something like a "framework directive," classification societies are comparable to the authorities that type-approve vehicles, and the anchor manufacturer is the carmaker who has to prove that its "model" meets the standard.

The procedure

Phase 1 – Design Approval: The "Type Approval"

The first step doesn't take place in the workshop, but on paper — today, in CAD software: this is design approval, commonly known as type approval.

The manufacturer submits to the classification society:

general assembly and detail drawings (shape, flukes, stock, shank, pivots/joints)
material specifications and manufacturing processes (forging, welding);
any supporting notes and strength calculations.

The society's experts verify that:

the geometry is consistent with the rules on sizing and anchor type;
the proposed materials meet the specifications for steels approved for anchors (for example, forged steels compliant with the UR requirements on materials);
the design is compatible with the required performance categories (ordinary anchor, HHP, SHHP).

To use the analogy again, it's much like a new car model being reviewed before it ever goes into series production: on paper, the structure, materials, and overall concept are checked against certain safety standards, before moving on to actual dynamic testing.

If the outcome is positive, the anchor model officially becomes a "type-approved anchor" with that classification society.

Phase 2 – HHP and SHHP: Measuring Holding Power at Sea

Many modern anchors carry designations such as HHP or SHHP: these aren't commercial brand names, but performance classifications formally recognized by the classification societies.

HHP (High Holding Power): in sea trials, the anchor must demonstrate a holding capacity at least twice that of an ordinary stockless anchor (i.e. the classic anchor "without a stock" — the large transverse crossbar — widely used on large commercial vessels).
SHHP (Super High Holding Power): requires holding power of at least four times that of an ordinary anchor of the same weight, or at least twice that of an already-approved HHP anchor.

Holding power on the seabed alone is not assessed in a laboratory but at sea: the anchor being certified is tested side by side with a "standard anchor" on different types of seabed (sand, mud, clay, and so on), with the forces involved measured using dynamometers.

You could compare it to crash tests or braking tests for cars: a theoretical calculation isn't enough — the model's actual holding performance is verified in the field against a known reference.

For mechanical strength and load testing (proof load and tensile tests on anchors and related equipment), test benches come into play instead.

In this field, Posidonia operates the most powerful horizontal pull test bench in the Mediterranean: a structure almost 30 metres long, capable of testing up to roughly 500 tonnes, driven by a hydraulic ram.
The bench is calibrated every year by the Politecnico di Milano (Milan Polytechnic) and operates under the supervision — and with the subsequent approval — of Lloyd's Register of Shipping, the Italian Navy, and the other IACS classification societies, ensuring that the tests performed are recognized and accepted internationally.

Only after these tests can the model be officially listed in the class documentation as an HHP or SHHP anchor, for a given weight range.

Phase 3 – Manufacturer Approval: From Prototype to Series Production

Once an anchor type has been approved, it's essential to ensure that every anchor produced genuinely matches the certified "prototype." This is why the rules require that anchors be manufactured only at facilities approved by the classification society.

Among other things, this involves:

qualified and documented forging and welding processes;
personnel certified for critical activities (welders, non-destructive testing operators);
a structured quality management system (often based on ISO 9001, but reviewed and "translated" into classification-specific requirements).

Industry experience shows just how crucial this step is: well-known cases of anchors produced using steels other than those declared have shown that even a sound design can run into problems if the supply chain and in-house quality controls aren't kept under strict oversight.

In practical terms, this phase is comparable to certifying a specific car manufacturing plant: it isn't enough for the vehicle's design to be type-approved — the plant producing it must also be shown capable of replicating that standard consistently, batch after batch.

Phase 4 – Testing and Inspection of the Individual Piece

For anyone buying or fitting an anchor, the heart of the process lies in the checks carried out on the individual unit. The IACS rules (UR W29) set out a series of standardized checks that every certified anchor must pass.

DIMENSIONAL AND VISUAL INSPECTION

The anchor is checked against the approved drawing: lengths, thicknesses, angles, and the play of moving parts, along with any welds and castings, must fall within the specified tolerances. At the same time, a visual inspection is carried out to identify cracks, porosity, or other visible defects.

LOAD TESTING (PROOF LOAD TEST)

Every anchor undergoes a load test: a controlled pull applied to a force level set according to the anchor's weight and category. For SHHP anchors, the required load level is higher than that for an ordinary anchor of the same mass, to ensure safety margins consistent with the higher declared holding power.

The purpose here isn't to measure holding power on the seabed (that's assessed during the type-testing phase), but to verify that the structure withstands a very high load without permanent deformation.

NON-DESTRUCTIVE TESTING

Depending on the anchor type and material, non-destructive testing (NDT) is carried out, including:

dye penetrant or magnetic particle testing to detect surface cracks;
ultrasonic testing to check for internal defects in critical areas.

These checks are especially important after the load test, since they can reveal defects that opened up or grew larger under stress.

In some cases, particularly for new configurations, the classification society may require additional tests, such as drop tests or hammer tests, to further qualify the product's behaviour.

Phase 5 – Markings: Reading the Anchor Like a Document

A certified anchor bears a set of permanent markings stamped or engraved into the metal, which effectively serve as its "identity card."

Under classification society rules, these markings typically include:

the symbol or abbreviation of the classification society (RINA, LR, DNV, etc.);
the holding-power class, where applicable (for example "HHP" or "SHHP");
the anchor's nominal weight;
the manufacturer's mark and, often, a traceability code (batch, heat/cast number, serial number).

Markings can be applied by stamping or by an approved engraving method, provided they remain permanent and legible over time. For anyone working on board or in a shipyard, learning to "read" these markings means being able to trace the physical piece back to its certificates and to the society that approved it — much like a car's number plate and registration document.

Phase 6 – Documentation: What to Request from Supplier and Shipyard

Physical markings always go hand in hand with a documentary component. For a certified anchor, it's standard practice to require at least:

a type approval certificate: confirms that the anchor model, for a given weight range, is recognized as an ordinary, HHP, or SHHP anchor under the classification society's rules;
a test certificate for the anchor (or the batch): reports the load test results, the checks carried out, and cross-references to the markings;
material certificates (e.g. EN 10204 3.1/3.2): link the steel used to the approved quality specifications.

For anyone working on newbuilds or refits, keeping this documentation together with the vessel's other records means being able to demonstrate — in the event of an inspection or an incident — that the anchoring equipment meets its declared standards.

A Quick Operational Guide to Following the Process

If your goal is to follow the certification process with full awareness — whether as a client, designer, or shipowner — here are the key questions to ask at each stage of the supply chain:

Is the anchor model "type approved" by a classification society?
Check whether a type approval certificate exists and, if HHP/SHHP classes are claimed, that they correspond to an official classification — not just a marketing claim.
Is the facility producing the anchor approved?
Ask whether the manufacturer is recognized as an "approved manufacturer" by the classification society, and how quality control is managed.
Are there test results and certificates for the individual piece?
Request a copy of the test certificate (proof load, NDT) and the material certificates, especially for larger, higher-importance anchors or on vessels subject to SOLAS/classification rules.
Do the markings match the documentation?
Check that what's physically stamped on the anchor (class, HHP/SHHP, weight, manufacturer) matches what's stated in the certificates.