Fluke and plow anchors
Discover Boating describes two designs:
| Type | Strengths | Limits |
|---|---|---|
| Fluke (Danforth-type) | Folds flat, light, holds well in sand or mud | Holds poorly on rock |
| Plow (scoop) | Holds on most bottoms and usually resets when the wind shifts | Does not fold and is heavier, so suits boats with a bow roller and windlass |
Discover Boating tells owners to size the anchor from the manufacturer's guidance. We did not collect anchor sizing tables, so we do not give sizes here.
What a 2013 resetting test found
Practical Sailor's 2013 test looked at how anchors reset when the direction of pull changes. This is a historical result: it used 12 anchors under 20 lb, sized for 20 to 25 ft trailer-sailers, and we have not read any newer Practical Sailor anchor results. The test pulled each anchor, then swung the pull 90 or 180 degrees, in sand and clay and in mud. Its findings:
- CQR and fisherman. The CQR did not reset on any re-pull. The traditional fisherman anchor set only in sand, with little holding power.
- V-shaped soles. Anchors with a protruding V-shaped sole (Spade, Ultra, Kobra) did best when the pull swung 90 degrees.
- Convex designs. Delta, Excel and Kobra were good all-round performers.
- Roll-bar designs. Rocna and Manson Supreme did well at 90 degrees, but at 180 degrees in sand and clay they dragged upside down holding a clod of seabed. Apart from the CQR, they had the worst resetting in this test.
- No fluke anchor. No Danforth-type anchor was tested, because none could be found locally in Australia, where the test was run.
Practical Sailor's broader conclusions were that high holding power does not guarantee good resetting, that concave anchors can pick up mud, and that slotted shanks should normally be locked off. The test covered only small anchors, and products may have changed since 2013.
Rode and scope
The rode is what connects the anchor to the boat. Discover Boating says a typical rode is a length of chain at the anchor end with nylon line running to the boat. Cruising World recommends nylon for anchor rode because its stretch absorbs shock.
Discover Boating defines scope as rode length divided by water depth; ASA also counts the height of the bow above the water (see anchoring). Discover Boating recommends 7:1 where there is room, for example about 70 ft of rode in 10 ft of water.
The Sailboat Cruiser reference site explains why chain helps: the sag of hanging chain, called the catenary, acts as a spring against shock loads, and a combined chain-and-rope rode adds stretch from the rope. How to set and use an anchor is covered under anchoring.
Chain grades
The Sailboat Cruiser describes the grades of anchor chain:
- Proof Coil (Grade 30)
- Not calibrated, and often fits windlass gypsies poorly.
- BBB (Grade 30)
- Shorter, calibrated links.
- High-Test (Grade 40/43)
- Made from stronger steel.
- Grade 70
- Made from stronger, heat-treated steel. The same source warns that re-galvanizing it is risky because the heat can soften the steel.
It also warns that pairing galvanized chain with stainless fittings invites galvanic corrosion.
Racing requirements
US Sailing's 2025.2 Safety Equipment Requirements for nearshore racing, in force for 2026, require an anchor with suitable chain and line. Organizing authorities can change equipment items in the Notice of Race, so check the documents for your event.