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26-410: The standard fluyt design minimized or completely eliminated its armaments to maximize available cargo space, and used block and tackle extensively to facilitate ship operations. Another advantage of its pear-shape (when viewed from the fore or aft) was a shallow draft which allowed the vessel to bring cargo in and out of ports and up and down rivers which other vessels could not reach. This ship class

52-445: A block and fall: F a = L N 1 eff {\displaystyle F_{a}={\frac {L}{N}}{\frac {1}{\textit {eff}}}} where F a {\displaystyle F_{a}} is the force applied to the hauling part of the line (the input force), L {\displaystyle L} is the weight of the load (the output force), N {\displaystyle N}

78-432: A rope threaded through the pulleys is called tackle. The process of threading ropes or cables through blocks is called " reeving ", and a threaded block and tackle is said to have been "rove". A block and tackle system amplifies the tension force in the rope to lift heavy loads. They are common on boats and sailing ships , where tasks are often performed manually, as well as on cranes and drilling rigs , where once rove,

104-471: A tackle is offset by both the increased length of rope needed and the friction in the system. In order to raise a block and tackle with a mechanical advantage of 6 a distance of 1 metre, it is necessary to pull 6 metres of rope through the blocks. Frictional losses also mean there is a practical point at which the benefit of adding a further sheave is offset by the incremental increase in friction which would require additional force to be applied in order to lift

130-461: Is a persistent myth that the fluyt was developed to evade Sound Tolls . The toll registers, however, show that during the 70 years from 1562 to 1632 it was a well-established procedure in the Sound for the toll-officers to use the bills of lading to determine the loading-capacities of the vessels passing through. They did not employ any sort of measuring device to assess the width, length, and depth of

156-399: Is characterized by the use of a single continuous rope to transmit a tension force around one or more pulleys to lift or move a load. Its mechanical advantage is the number of parts of the rope that act on the load. The mechanical advantage of a tackle dictates how much easier it is to haul or lift the load. If frictional losses are neglected, the mechanical advantage of a block and tackle

182-425: Is equal to the number of parts in the line that either attach to or run through the moving blocks—in other words, the number of supporting rope sections. An ideal block and tackle with a moving block supported by n rope sections has the mechanical advantage (MA), M A = F B F A = n , {\displaystyle MA={\frac {F_{B}}{F_{A}}}=n,\!} where F A

208-601: Is possible by use of the sheave friction factor, K {\displaystyle K} (which may be obtainable from the manufacturer or published tables ). The relevant equation is: eff = K N − 1 K S N ( K − 1 ) . {\displaystyle {\textit {eff}}={\frac {K^{N}-1}{K^{S}N(K-1)}}.} Typical K {\displaystyle K} values are 1.04 for roller bearing sheaves and 1.09 for plain bearing sheaves (with wire rope). The increased force produced by

234-425: Is the hauling (or input) force and F B is the load. Consider the set of pulleys that form the moving block and the parts of the rope that support this block. If there are n of these parts of the rope supporting the load F B , then a force balance on the moving block shows that the tension in each of the parts of the rope must be F B /n. This means the input force on the rope is F A = F B /n. Thus,

260-444: Is the ideal mechanical advantage of the system (which is the same as the number of segments of line extending from the moving block), and eff {\displaystyle {\textit {eff}}} is the mechanical efficiency of the system (equal to one for an ideal frictionless system; a fraction less than one for real-world systems with energy losses due to friction and other causes). If S {\displaystyle S}

286-440: Is the most efficient use of equipment and resources. For example, if the load is to be hauled parallel to the ground, reeving to advantage enables the pulling force to be in the direction of the load movement, allowing obstacles to be managed more easily. Reeving to disadvantage adds an extra sheave to change the direction of the pulling line to a potentially more ergonomic direction, which increases friction losses without improving

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312-539: Is the number of sheaves in the purchase, and there is a roughly x {\displaystyle x} % loss of efficiency at each sheave due to friction, then: 1 eff ≈ 1 + S x 100 . {\displaystyle {\frac {1}{\textit {eff}}}\approx 1+S{\frac {x}{100}}.} This approximation is more accurate for smaller values of S {\displaystyle S} and x {\displaystyle x} . A more precise estimate of efficiency

338-422: Is threaded through the pulleys to provide mechanical advantage that amplifies the force applied to the rope. Hero of Alexandria described cranes formed from assemblies of pulleys in the first century. Illustrated versions of Hero's Mechanica (a book on raising heavy weights) show early block and tackle systems. A block is a set of pulleys or sheaves mounted on a single frame. An assembly of blocks with

364-522: The Hector is operated by the Hector Quay Society and is open to the public. Block and tackle A block and tackle or only tackle is a system of two or more pulleys with a rope or cable threaded between them, usually used to lift heavy loads. The pulleys are assembled to form blocks and then blocks are paired so that one is fixed and one moves with the load. The rope

390-723: The Dutch dominated the market. During the 17th century, English companies leased ships like the Swan to carry colonists to America. The Hector , constructed in Pictou , Nova Scotia, and launched in 2000, is a replica of an early 18th-century fluyt which, in the summer of 1773 carried 189 Scottish immigrants to Nova Scotia. The replica was constructed according to line drawings from the Maritime Museum Rotterdam , and built using traditional shipbuilding techniques. As of 2017,

416-451: The block and tackle reduces the input force by the factor n. Ideal mechanical advantage correlates directly with velocity ratio . The velocity ratio of a tackle is the ratio between the velocity of the hauling line to that of the hauled load. A line with a mechanical advantage of 4 has a velocity ratio of 4:1. In other words, to raise a load at 1 metre per second, the hauling part of the rope must be pulled at 4 metres per second. Therefore,

442-638: The later part of the 17th century as English merchants, seeing how much cheaper Dutch shipping was, acquired Dutch-built ships captured in the Anglo-Dutch wars . The design of the fluyt evolved from the early galleon , to which it bore a resemblance; the galleon, developed in Spain, was also built in the Netherlands, then under the same monarchs. Fluyts typically had a displacement of 200 to 300 tons and were approximately 80 feet (24 metres) in length. It

468-492: The load. Too much friction may result in the tackle not allowing the load to be released easily, or by the reduction in force needed to move the load being judged insufficient because undue friction has to be overcome as well. When installing a block on an existing line, it is often inconvenient at best to thread the rope through the block to be added. Swing cheek blocks may be roughly divided into two categories: Pulley Too Many Requests If you report this error to

494-413: The mechanical advantage of a double tackle is 4. The mechanical advantage of any tackle can be increased by interchanging the fixed and moving blocks so the rope is attached to the moving block and the rope is pulled in the direction of the lifted load. In this case the block and tackle is said to be "rove to advantage." Diagram 3 shows three rope parts supporting the load W , which means the tension in

520-476: The rope is W/3 . Thus, the mechanical advantage is three-to-one. By adding a pulley to the fixed block of a gun tackle the direction of the pulling force is reversed though the mechanical advantage remains the same, Diagram 3a. This is an example of the Luff tackle. The decision of which to use depends on pragmatic considerations for the total ergonomics of working with a particular situation. Reeving to advantage

546-403: The tasks are performed by heavy equipment. In the diagram shown here, the number of rope sections of the tackles shown is as follows: Note that in the gun tackle, double tackle and threefold purchase, both blocks have the same number of pulleys (one, two and three, respectively) whereas the Luff tackle and Gyn tackle have mis-matched blocks with differing numbers of pulleys. A block and tackle

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572-414: The velocity ratio. Situations in which reeving to disadvantage may be more desirable include lifting from a fixed point overhead--the additional pulley allows pulling downwards instead of upwards so that the weight of the lifter can offset the weight of the load, or allows pulling sideways, enabling multiple lifters to combine effort. The formula used to find the effort required to raise a given weight using

598-439: The vessels and then calculate the size of the ships. The fluyt was square rigged with two or three masts. When rigged with three masts, the fore and main (front two) masts were square rigged, with the mizzen (rearmost) mast often rigged with a triangular lateen sail, as pictured above. Masts were much higher than those of galleons to allow for greater speed. At times fluyts were also armed and served as auxiliary vessels, which

624-522: The wreck's rudder is decorated with three flowers which is typical of Dutch-built ships of the era. This ship is believed to be named the Swan due to the sculpted body of a swan found in the wreckage. At the time it was customary to attach a figure depicting the name of the ship to the transom . Dutch fluyts were built and used in the 16th and 17th centuries as a contract-for-hire vessel. England had not yet established its own large-scale shipbuilding industry and

650-539: Was a common practice in the Baltic Sea . In 2003, Martin Mattenik and Deep Sea Productions, using side scanning sonar, discovered a shipwreck lying on the floor of the Baltic Sea . The wreck was visited five times between 2003 and 2010. The Baltic is unusual in that there is a thick layer of fresh water inhospitable to saltwater-loving shipworms and shipwrecks are protected from the ravages of shipworms. The top of

676-532: Was credited for making the Dutch more competitive in international trade, and was widely employed by the Dutch East India Company in the 17th and 18th centuries. However, its usefulness caused the fluyt to gain such popularity that similar designs were soon developed by seagoing competitors of the Dutch. For example, the English shipbuilding industry began to adapt the design of the fluyt during

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