Anchor Types & Selection

The Design Problem Every Anchor Solves

Every anchor must accomplish three things: penetrate the seabed, set (orient itself correctly under initial load), and hold (resist extraction under sustained and shock loads). Different designs make different trade-offs between these three requirements — and between performance in different bottom types.

A second design consideration is re-setting: when wind direction shifts 180 degrees, the rode slackens and the anchor may break out. A good anchor re-sets in the new direction quickly rather than sliding on the surface while the boat drifts.

Finally, stowage matters on a real boat. An anchor that stows flat on a bow roller is ready for use at any moment. One that must be broken down or wedged awkwardly onto the foredeck takes precious minutes to deploy in an emergency.

No single anchor is the best at everything. Understanding the design trade-offs lets you make an informed choice — and explains why many serious cruisers carry a second anchor of a different type.

Traditional Designs: CQR, Danforth, and Bruce

CQR (Plow): The classic hinged-shank plow anchor dominated offshore cruising from the 1950s through the 1990s. The hinged shank allows the fluke to follow when wind direction changes without breaking out fully. The CQR sets in sand and mud but requires a long run to set (it often skates on the surface before digging in) and is mediocre in weed. It's heavy for its holding power compared to modern designs, but it is proven over decades of offshore use. Still common on boats rigged before 2005.

Danforth (Fluke/Flat-plate): The Danforth uses two large flat flukes pivoting on a stock rod. It has excellent holding power in sand and mud per unit weight and stows flat. However, it is poor in weed, rock, and silt (buries too deep to recover), and it can be difficult to re-set. It's better as a kedge (secondary anchor) or stern anchor than as a primary bower on most cruising boats.

Bruce (Claw): The Bruce claw anchor was designed to hold drilling rigs and adapted for yachts. It has a distinctive three-claw geometry and sets quickly in sand. Its weaknesses are limited penetration depth (the claw sits more on the surface than other designs) and relatively poor holding-to-weight ratio in hard substrates. Many sailors use Bruce-type anchors as secondary stern anchors — quick to deploy, good for overnight stays in benign conditions.

Delta: A fixed-shank plow design (not hinged like the CQR). Generally regarded as a significant improvement over the CQR — it sets faster, holds better across a wider range of bottom types, and the fixed shank means more consistent pull geometry. The Delta became the standard primary anchor on many production sailboats through the 2000s.

Modern High-Performance Designs: Rocna, Spade, and Manson

From the late 1990s onward, a generation of new anchor designs emerged that significantly outperformed traditional anchors in controlled testing. These designs share common features: a concave fluke for deep penetration, a roll-bar or weighted tip that self-rights the anchor in any orientation, and a fixed high-rake shank that maximizes horizontal load on the buried fluke.

Rocna (and Vulcan): A roll-bar anchor with a large concave fluke and a sharp toe. The roll-bar ensures the anchor lands in the correct orientation regardless of how it hits the seabed — it cannot land fluke-up. Sets fast, holds in sand, mud, weed, and gravel. Re-sets well. The Rocna is regarded by many experienced cruisers as the best all-round primary anchor available. The Vulcan is the Rocna design without the roll-bar, for boats where the roll-bar doesn't fit the bow roller.

Spade: A French design that predates the Rocna and is equally capable. Uses a concave fluke and hollow shank that fills with substrate on entry, adding to holding mass. Excellent in sand and mud. Sets quickly. The Spade is arguably the gold standard for pure holding power but is more expensive than the Rocna.

Manson Supreme / Manson Boss: New Zealand designs that perform similarly to the Rocna. The Manson Boss uses a slightly different roll-bar geometry that some skippers prefer for bow roller compatibility on specific boat designs.

For most modern cruising boats, the decision is between Rocna/Vulcan, Spade, and Manson Supreme — all are significant upgrades over CQR and Bruce designs at similar or only slightly higher prices per kilogram.

Sizing Your Anchor and Rode

Manufacturer sizing tables give a starting point, but they assume favorable conditions. For a primary anchor, go one size heavier than the table minimum for your boat length — the marginal weight cost on deck is small compared to the holding power gained.

General sizing guidance for a modern anchor (Rocna/Spade/Manson) by boat length:

- Up to 9m (30ft): 10kg

- 9–12m (30–40ft): 15kg

- 12–15m (40–50ft): 20–25kg

- Over 15m (50ft+): 33–40kg

These weights assume good-to-moderate holding ground. In poor holding (weed, thin sand over rock), add at least one size.

Rode selection: All-chain rode provides maximum catenary and abrasion resistance on the seabed, but is heavy — a 40m chain rode weighs 25–35kg. For performance-oriented boats and coastal cruisers, a combination of 10–15m of chain at the anchor end and nylon braid for the remainder provides catenary at the anchor while reducing weight.

Chain grade: G30 (proof coil) is the minimum acceptable for an anchor rode. G43 (high-test) is stronger at equal weight and preferred for limited-storage boats. G70 (transport chain) is often used in high-load applications but must be matched to a compatible windlass gypsy.

Windlass capacity: Your windlass is rated for a chain load and weight. Confirm that your anchor, chain, and any line-to-chain swivel combination is within the windlass manufacturer's specification. An overloaded windlass motor burns out — usually in the worst possible conditions.