Definition
Anchor
An anchor is a device, typically made of metal, used to secure a vessel to the seabed to prevent it from drifting due to wind or current. The word "anchor" originates from the Latin "ancora" and the Greek "ἄγκυρα (ankȳra)".
Anchors can be either temporary or permanent. Temporary anchors are carried on board vessels and may be of different designs and weights. These are used to moor the vessel in a specific location. Permanent anchors, on the other hand, are used to create a mooring and are rarely moved, often requiring specialist service to do so.
Anchors achieve their holding power either by "hooking" into the seabed, by their weight, or a combination of the two. The weight of the anchor chain can be critical to the anchor's proper holding. Permanent moorings often use large concrete blocks or slabs resting on the seabed, while ship's anchors and semi-permanent mooring anchors derive significant holding power from their weight in addition to hooking or embedding in the bottom. Modern anchors for smaller vessels have metal flukes that hook onto rocks or bury themselves in soft seabeds.
The vessel is attached to the anchor by a rode, which can be made of rope, chain, or a combination. The ratio of the length of the rode to the water depth is known as the "scope". Holding ground refers to the area of the seabed that holds the anchor, and different anchor types are designed for different bottom types. In poor holding ground, the anchor's weight is more important, while in good holding ground, the anchor's ability to dig in provides significantly higher holding power.