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Anchor
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== History == === Evolution of the anchor === {{Main|History of the anchor}} [[File:Anchor types.jpg|thumb|upright=2|left|Anchors come in a wide variety of shapes, types, and sizes for different conditions, functions and vessels.]] The earliest anchors were probably rocks, and many rock anchors have been found dating from at least the [[Bronze Age]].<ref>Johnstone, Paul and McGrail, Seán (1989). ''The sea-craft of prehistory''. London: Routledge. {{ISBN|978-0-415-02635-2}}, p.82.</ref> Pre-European Māori waka (canoes) used one or more hollowed stones, tied with flax ropes, as anchors. Many modern moorings still rely on a large rock as the primary element of their design. However, using pure weight to resist the forces of a storm works well only as a permanent mooring; a large enough rock would be nearly impossible to move to a new location. The ancient Greeks used baskets of stones, large sacks filled with sand, and wooden logs filled with lead. According to [[Apollonius of Rhodes|Apollonius Rhodius]] and [[Stephanus of Byzantium|Stephen of Byzantium]], anchors were formed of stone, and Athenaeus states that they were also sometimes made of wood. Such anchors held the vessel merely by their weight and by their friction along the bottom.{{cn|date=June 2023}}{{clarify|How a wood anchor would hold. Most wood floats, and even dense wood has very little negative buoyancy and would be ineffective without some ballast weight|date=June 2023}} === Fluked anchors === [[File:Ladbyskibet anker.jpg|thumb|Anchor of the Ladby Ship]] [[Iron]] was afterwards introduced for the construction of anchors, and an improvement was made by forming them with teeth, or "flukes", to fasten themselves into the bottom. This is the iconic anchor shape most familiar to non-sailors. This form has been used since antiquity. The Roman [[Nemi ships]] of the 1st century AD used this form. The Viking [[Ladby ship]] (probably 10th century) used a fluked anchor of this type, made of iron, which would have had a wooden stock mounted perpendicular to the shank and flukes to make the flukes contact the bottom at a suitable angle to hook or penetrate.<ref>{{cite book |last1=Sørensen |first1=Anne |title=Ladby: A Danish Ship-Grave from the Viking Age |date=2001 |publisher=Viking Ship Museum |pages=52}}</ref> === Admiralty anchor === [[File:Admiralty anchor.JPG|thumb|left|An Admiralty Pattern anchor; when deployed on the seafloor the stock forces one of its flukes into the bottom.]] The Admiralty Pattern anchor, or simply "Admiralty", also known as a "Fisherman", consists of a central shank with a ring or [[shackle]] for attaching the rode (the rope, chain, or cable connecting the ship and the anchor). At the other end of the shank there are two arms, carrying the flukes, while the stock is mounted to the shackle end, at ninety degrees to the arms. When the anchor lands on the bottom, it generally falls over with the arms parallel to the seabed. As a strain comes onto the rope, the stock digs into the bottom, canting the anchor until one of the flukes catches and digs into the bottom. The Admiralty Anchor is an entirely independent reinvention of a classical design, as seen in one of the Nemi ship anchors. This basic design remained unchanged for centuries, with the most significant changes being to the overall proportions, and a move from stocks made of wood to iron stocks in the late 1830s and early 1840s.{{cn|date=September 2020}} Since one fluke always protrudes up from the set anchor, there is a great tendency of the rode to foul the anchor as the vessel swings due to wind or current shifts. When this happens, the anchor may be pulled out of the bottom, and in some cases may need to be hauled up to be re-set. In the mid-19th century, numerous modifications were attempted to alleviate these problems, as well as improve holding power, including one-armed mooring anchors. The most successful of these ''patent anchors'', the Trotman Anchor,<ref>{{cite web |title=Art in the Park – Iron Stock Trotman Anchor (DA 64) |first=Rachel |last=Conley |date=2 May 2013 |website=marinersmuseum.org |access-date=2 September 2020 |url=https://blog.marinersmuseum.org/2013/05/art-in-the-park-iron-stock-trotman-anchor/ |archive-date=6 November 2020 |archive-url=https://web.archive.org/web/20201106094952/https://blog.marinersmuseum.org/2013/05/art-in-the-park-iron-stock-trotman-anchor/ |url-status=dead }}</ref> introduced a pivot at the centre of the crown where the arms join the shank, allowing the "idle" upper arm to fold against the shank. When deployed the lower arm may fold against the shank tilting the tip of the fluke upwards, so each fluke has a tripping palm at its base, to hook on the bottom as the folded arm drags along the seabed, which unfolds the downward oriented arm until the tip of the fluke can engage the bottom.{{cn|date=September 2020}} Handling and storage of these anchors requires special equipment and procedures. Once the anchor is hauled up to the [[hawsepipe]], the ring end is hoisted up to the end of a timber projecting from the bow known as the [[cathead]]. The crown of the anchor is then hauled up with a heavy tackle until one fluke can be hooked over the rail. This is known as "catting and fishing" the anchor. Before dropping the anchor, the fishing process is reversed, and the anchor is dropped from the end of the cathead. === Stockless anchor === {{main|Stockless anchor}} [[File:Stockless anchor 1 NT.PNG|thumb|The action of a stockless anchor being set]] The stockless anchor, patented in England in 1821,<ref name=Brit>"anchor" in ''[[Encyclopædia Britannica|The New Encyclopædia Britannica]]''. Chicago: [[Encyclopædia Britannica Inc.]], 15th edn., 1992, Vol. 1, pp. 377–8.</ref> represented the first significant departure in anchor design in centuries. Although their holding-[[power-to-weight ratio]] is significantly lower than admiralty pattern anchors, their ease of handling and stowage aboard large ships led to almost universal adoption. In contrast to the elaborate stowage procedures for earlier anchors, stockless anchors are simply hauled up until they rest with the shank inside the hawsepipes, and the flukes against the hull (or inside a recess in the hull called the anchor box). While there are numerous variations, stockless anchors consist of a set of heavy flukes connected by a pivot or ball and socket joint to a shank. Cast into the crown of the anchor is a set of tripping palms, projections that drag on the bottom, forcing the main flukes to dig in.
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