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A stockless anchor (or "patent anchor") is a streamlined derivation of the traditional Admiralty anchor used aboard large ships. Patented in England in 1821, [1] it eliminated the stock of the Admiralty, making it both easier to handle and stow. Though it did not hold as well as an Admiralty, the trade-off proved acceptable and the stockless anchor became widely popular, and it remains so.
The stockless anchor is an improved version of the Admiralty anchor it is derived from. It has two flukes that pivot on the same plane perpendicular to the shank. [2] The weight of the shank and accompanying chain, or the shank angled under tension, keep the anchor laying flat on the sea floor.
The stockless anchor is a simple design with no unnecessary parts. This makes it comparatively easy to handle and store. [3] The simple geometry of its design makes breaking it from the bottom a relatively easy and reliable procedure. [4] The shank being able to pivot while the flukes are embedded in the sea floor minimizes wear on attachment hardware. [4] Another advantage of the pivoting shank design is that the anchor generally will still hold even if the wind and or current changes direction and causes the vessel to pull on the anchor from a slightly different angle. [3] Due to the simple design of the stockless anchor, it is capable of free falling much faster in water than other more bulky anchor types according to a study done by The Japan Institute of Navigation. [5]
In terms of disadvantages, the stockless anchor is shown to perform poorly in soft cohesive bottoms such as soil or sand compared to other anchor types made specifically for that type of bottom. [6] Also, the Navy Stockless Anchor has an efficiency rate of 4-6, compared to other types of anchors with efficiency rates ranging from 15 to 55. [7]
An anchor is a device, normally made of metal, used to secure a vessel to the bed of a body of water to prevent the craft from drifting due to wind or current. The word derives from Latin ancora, which itself comes from the Greek ἄγκυρα.
A plough or plow is a farm tool for loosening or turning the soil before sowing seed or planting. Ploughs were traditionally drawn by oxen and horses but in modern farms are drawn by tractors. A plough may have a wooden, iron or steel frame with a blade attached to cut and loosen the soil. It has been fundamental to farming for most of history. The earliest ploughs had no wheels; such a plough was known to the Romans as an aratrum. Celtic peoples first came to use wheeled ploughs in the Roman era.
A screwdriver is a tool, manual or powered, used for turning screws.
The MacPherson strut is a type of automotive suspension system that uses the top of a telescopic damper as the upper steering pivot. It is widely used in the front suspension of modern vehicles. The name comes from American automotive engineer Earle S. MacPherson, who invented and developed the design.
A mooring is any permanent structure to which a seaborne vessel may be secured. Examples include quays, wharfs, jetties, piers, anchor buoys, and mooring buoys. A ship is secured to a mooring to forestall free movement of the ship on the water. An anchor mooring fixes a vessel's position relative to a point on the bottom of a waterway without connecting the vessel to shore. As a verb, mooring refers to the act of attaching a vessel to a mooring.
An easel is an upright support used for displaying and/or fixing something resting upon it, at an angle of about 20° to the vertical. In particular, easels are traditionally used by painters to support a painting while they work on it, normally standing up, and are also sometimes used to display finished paintings. Artists' easels are still typically made of wood, in functional designs that have changed little for centuries, or even millennia, though new materials and designs are available. Easels are typically made from wood, aluminum or steel.
Wingtip devices are intended to improve the efficiency of fixed-wing aircraft by reducing drag. Although there are several types of wing tip devices which function in different manners, their intended effect is always to reduce an aircraft's drag. Wingtip devices can also improve aircraft handling characteristics and enhance safety for following aircraft. Such devices increase the effective aspect ratio of a wing without greatly increasing the wingspan. Extending the span would lower lift-induced drag, but would increase parasitic drag and would require boosting the strength and weight of the wing. At some point, there is no net benefit from further increased span. There may also be operational considerations that limit the allowable wingspan.
A truss is an assembly of members such as beams, connected by nodes, that creates a rigid structure.
A centreboard or centerboard (US) is a retractable hull appendage which pivots out of a slot in the hull of a sailboat, known as a centreboard trunk (UK) or centerboard case (US). The retractability allows the centreboard to be raised to operate in shallow waters, to move the centre of lateral resistance, to reduce drag when the full area of the centreboard is not needed, or when removing the boat from the water, as when trailering. A centreboard which consists of solely a pivoting metal plate is called a centerplate. A daggerboard is similar but slides vertically rather than pivoting.
Boating is the leisurely activity of travelling by boat, or the recreational use of a boat whether powerboats, sailboats, or man-powered vessels, focused on the travel itself, as well as sports activities, such as fishing or waterskiing. It is a popular activity, and there are millions of boaters worldwide.
A corkscrew is a tool for drawing corks from wine bottles and other household bottles that may be sealed with corks. In its traditional form, a corkscrew simply consists of a pointed metallic helix attached to a handle, which the user screws into the cork and pulls to extract it. Corkscrews are necessary because corks themselves, being small and smooth, are difficult to grip and remove, particularly when inserted fully into an inflexible glass bottle. More recent styles of corkscrew incorporate various systems of levers that further increase the amount of force that can be applied outwards upon the cork, making the extraction of difficult corks easier.
A single-speed bicycle is a type of bicycle with a single gear ratio. These bicycles are without derailleur gears, hub gearing or other methods for varying the gear ratio of the bicycle.
A bottle opener is a device that enables the removal of metal bottle caps from glass bottles. More generally, it might be thought to include corkscrews used to remove cork or plastic stoppers from wine bottles.
In watercraft, a racing shell is an extremely narrow, and often comparatively long, rowing boat specifically designed for racing or exercise. It is equipped with long oars, outriggers to hold the oarlocks away from the boat, and sliding seats. The boat's long length and semicircular cross-section reduce drag to a minimum. This makes the boat both fast and unstable. It must be balanced by the rowers to avoid tipping. Being able to balance – or "set" – the boat while putting maximum effort into the oars is therefore an essential skill of sport rowing.
An oblique wing is a variable geometry wing concept. On an aircraft so equipped, the wing is designed to rotate on center pivot, so that one tip is swept forward while the opposite tip is swept aft. By changing its sweep angle in this way, drag can be reduced at high speed without sacrificing low speed performance. This is a variation on the classic swing-wing design, intended to simplify construction and retain the center of gravity as the sweep angle is changed.
In an automobile, ball joints are spherical bearings that connect the control arms to the steering knuckles, and are used on virtually every automobile made. They bionically resemble the ball-and-socket joints found in most tetrapod animals.
Bicycle suspension is the system, or systems, used to suspend the rider and bicycle in order to insulate them from the roughness of the terrain. Bicycle suspension is used primarily on mountain bikes, but is also common on hybrid bicycles.
The history of the anchor dates back millennia. The most ancient anchors were probably rocks and many rock anchors have been found dating from at least the Bronze Age. Many modern moorings still rely on a large rock as the primary element of their design. However, using pure mass to resist the forces of a storm only works well as a permanent mooring; trying to move a large enough rock to another bay is nearly impossible.
Offshore embedded anchors are anchors intended for offshore use that derive their holding capacity from the frictional, or bearing, resistance of the surrounding soil, as opposed to gravity anchors, which derive their holding capacity largely from their weight. As offshore developments move into deeper waters, gravity-based structures become less economical due to the large size needed and the consequent cost of transportation.
A vertical-axis wind turbine (VAWT) is a type of wind turbine where the main rotor shaft is set transverse to the wind while the main components are located at the base of the turbine. This arrangement allows the generator and gearbox to be located close to the ground, facilitating service and repair. VAWTs do not need to be pointed into the wind, which removes the need for wind-sensing and orientation mechanisms. Major drawbacks for the early designs included the significant torque ripple during each revolution, and the large bending moments on the blades. Later designs addressed the torque ripple by sweeping the blades helically. Savonius vertical-axis wind turbines (VAWT) are not widespread, but their simplicity and better performance in disturbed flow-fields, compared to small horizontal-axis wind turbines (HAWT) make them a good alternative for distributed generation devices in an urban environment.
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