A stockless anchor is an anchor built without a stock. The word is easy to misread, so start with the distinction: the stock is a crossbar — a horizontal arm set at right angles to the arms and flukes of the lower part of the anchor — and it is not the shank. The shank is the anchor's main shaft. A stockless anchor still has a shank; what it lacks is the separate crossbar that runs across it.
This article covers the stockless anchors fitted to large commercial ships: what each part is called, how a conventional pivoting-head stockless anchor behaves on the seabed, and why the absence of the stock matters when the anchor is stowed at the bow.
The parts of a stockless anchor
The names below are the terms used in classic anchor diagrams; the Encyclopædia Britannica entry on anchors uses the same vocabulary. Individual stockless designs vary in proportion and in how the head is built, but the basic names carry across.
| Term | What it is | Notes |
|---|---|---|
| Shank | The anchor's main shaft | Joined to each arm at the crown — this is the part that is not the stock |
| Crown | The junction where the shank meets the arms | On the conventional pivoting-head pattern, crown, arms and flukes form one piece |
| Arm | The limb that carries a fluke | |
| Fluke | The end of the arm that engages the seabed | Long and heavy on the conventional stockless pattern |
| Palm | The flat face of the fluke | Traditionally drawn as a triangular face, not a shape every design must follow |
| Bill | The pointed tip of the fluke | The point that digs into the ground |
| Shackle / ring | The fitting where the chain or cable is attached |
How a conventional pivoting head works
On the conventional pivoting-head stockless pattern, the crown, arms and flukes are cast in one piece and can pivot slightly from side to side on the shank. That small range of movement is the key behaviour of this pattern: the head is not rigidly fixed to the shank but can tilt as the anchor is dragged, so the flukes can rotate rather than staying locked at one angle. Other stockless designs differ in how the head is built and connected — read "pivoting head" as the common conventional arrangement, not a rule that covers every anchor called stockless.
Setting on the seabed
When the anchor is dragged across the bottom, the seabed acts on the projecting shoulders at the base of the flukes, and under continued drag that action tends to rotate the flukes down into the bottom. Whether and how deeply an anchor sets depends on the seabed, the anchor and how it is deployed, so read the mechanism as a qualitative description rather than a performance figure.
Why stowage in the hawse pipe matters
Ease of handling and stowing helped bring stockless anchors into wide use on large ships (Britannica). Housing the anchor at the bow, though, is a ship-specific geometry problem, not a property of the word "stockless." The Common Structural Rules for Bulk Carriers and Oil Tankers (January 2019, Part 1, Chapter 11, Section 3, 3.8.1) require hawse pipes to be positioned and sloped so as to create an easy lead for the chain cables and efficient housing for the anchors where the latter are of the retractable type, avoiding damage to the hull during those operations. In practice that means the anchor, the hawse pipe and the pocket have to suit one another on each vessel, and the fit is checked against the drawings and the actual pipe arrangement. The stockless label on its own does not make a stow work.
Stockless is a family, not one design
"Stockless" names a family of anchors rather than a single standard shape. Hall and Spek anchors are examples of stockless anchor designs, and different designs can differ in head shape and in detailed construction. Because the term describes the absence of the stock and nothing more, two stockless anchors from different makers should not be assumed to be interchangeable in geometry or behaviour just because they share the label.
Where to go next
If you are new to the family as a whole, start with the overview in Types of Ship Anchors: Hall, Spek and AC-14, then look at how an anchor develops resistance once it is set in How Ship Anchors Work: Holding Power. For the two designs named above, see the Spek anchor and the Type A.B.C. Hall anchor pages, or browse the full marine anchor range.
References
- Encyclopædia Britannica, "Anchor" — https://www.britannica.com/technology/anchor-nautical-device
- Britannica Kids, "anchor" — https://kids.britannica.com/scholars/article/anchor/7402
- Common Structural Rules for Bulk Carriers and Oil Tankers, January 2019, Part 1 Chapter 11 Section 3 (Hawse pipes) — https://www.imorules.com/GUID-AC6535E2-4B3B-4E12-AB63-C3D0F72E4FCA.html
- Wärtsilä Encyclopedia, "Anchor" — https://www.wartsila.com/encyclopedia/term/anchor
