In commercial shipping, a high holding power (HHP) anchor is not a shape or a model name—it is a performance grade. Under IACS UR A1 (Rev.8, June 2023), an HHP anchor is one whose holding power is at least twice that of an ordinary stockless anchor of the same mass, and it must be suitable for ship's use without prior adjustment or special placement on the seabed.[1] The term therefore answers a comparison question—how much does it hold relative to a standard stockless anchor—rather than a naming question about its outline.
The rest of this article explains where that "at least twice" figure comes from, why structure, design name and performance grade are separate ideas, and what an HHP label does and does not establish for a commercial vessel.
"At least twice" is a comparison, not a description
The figure only has meaning against a baseline. The rule measures an HHP anchor against an ordinary stockless anchor of the same mass: the candidate must develop at least double the holding power of that ordinary anchor.[1]
The comparison assumes the anchor is deployed the way a bower anchor normally is. A design that only develops its holding power after being set in some particular way does not fit the description.
What the definition does not say matters too. It does not promise a result in any specific anchorage. Twice an ordinary stockless anchor is a graded comparison established under test conditions, not a guarantee of what a given anchor will do on a given seabed on a given day.
Structure, design name and performance grade are different things
Stockless is a structural description of an anchor family; Hall and Spek are named examples of stockless designs.[2] Inside that family, individual design names describe particular geometries. Each of those is a product design, not a level of performance.
HHP sits on a separate axis. It is a grade that a design can be approved to, based on its measured holding power relative to the ordinary stockless baseline. "HHP" is not a synonym for a type of geometry, so the same word can sit in front of anchors that look quite different—the label points to proven holding performance, not to the outline of the steel.
If you are still sorting the names apart, our guide to commercial ship anchor types covers how designs such as Hall, Spek and AC-14 differ.
Approval rests on full-scale comparison, not on a label
A claim to the HHP grade is meant to be supported by full-scale holding-power tests confirming that the anchor develops at least twice the holding power of an ordinary stockless anchor of the same mass.[1] These are comparison tests conducted under the rule's specified conditions, across different bottom types, with the holding pull measured.[1] Where an ordinary stockless anchor is unavailable, the cited rule permits a previously approved HHP anchor to be used as the reference.[1]
That structure is what matters when you weigh a claim. The evidence is a measured comparison between real anchors in real ground—not a drawing, an appearance or a marketing word. A design's test data, not its looks, is what the grade rests on.
It is also worth separating the holding-power test from a strength (proof-load) test. A proof-load test checks that the anchor's structure withstands a defined load; it says nothing about how much the anchor grips.[1] "How strong" and "how much it holds" are different questions, and a proof-load result does not, by itself, establish an anchor's holding-power grade.
| Term | What it refers to | What it is based on | What it does not, by itself, prove |
|---|---|---|---|
| Ordinary stockless anchor | The baseline anchor family, with no stock | Reference category used in the cited rule | That it is the best choice for a particular vessel |
| High holding power (HHP) | A holding-power grade | Full-scale tests showing at least twice the ordinary stockless holding power[1] | A result in a particular anchorage, or any specific geometry |
| Design name (Hall, Spek, AC-14, …) | One product's geometry | Its drawing and product specification | That the design is approved to any performance grade |
| Approved design vs. delivered anchor | A grade applies to an approved design; a delivered anchor is one physical unit | Check the scope of the design approval, and whether the documents supplied match the actual unit | That a document for a single unit demonstrates approval of an entire design range |
A lower assigned mass is conditional, not automatic
One reason the HHP grade draws attention is that the applicable rules may allow an approved HHP bower anchor to be assigned a lower required mass than an ordinary stockless bower anchor listed in the same equipment table.[1]
The key word is may. The allowance depends on the anchor having passed the full-scale tests and been accepted, and on the rules that apply to the specific vessel. It is not an automatic weight saving, and it does not replace confirming the actual requirement for the ship in question, which is a matter for the vessel's applicable rules and approval. Treat any lower mass figure as something to verify, not as a property of the word "HHP".
The same rules also describe a higher grade, super high holding power (SHHP), which has its own path to approval and its own limits on where and how it may be used.[1]
Putting the term to work
HHP describes a proven level of holding power relative to an ordinary stockless anchor—it is not a shape, a part number or a guarantee for a particular seabed. Reading the term correctly means keeping the performance grade, the design name and the structural family apart, and asking what test evidence sits behind a claim.
To go further, browse the Andy Marine anchor range to compare designs, or read our explanation of how anchor holding power develops for the mechanism behind the term. When you ask about a specified anchor, include the design name, the required mass and the available drawing or specification; those identify the product, while final suitability stays subject to the vessel's applicable design and approval requirements.
References
[1] IACS, UR A1 — Anchoring Equipment, Rev.8, June 2023, clauses A1.4.1.2, A1.4.2 and A1.4.4 (PDF, ClassNK-hosted copy). Cited for the HHP definition, the full-scale comparison framework and the separation of holding-power from strength testing; not as a determination of the rules applicable to an individual vessel.
[2] Wärtsilä Encyclopedia of Marine Technology, "Anchor" (entry listing stockless anchors as SPEK or HALL type). Cited for the structural naming of stockless designs only.
