1.
Cross section (geometry)
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In geometry and science, a cross section is the intersection of a body in three-dimensional space with a plane, or the analog in higher-dimensional space. Cutting an object into slices creates many parallel cross sections, conic sections – circles, ellipses, parabolas, and hyperbolas – are formed by cross-sections of a cone at various different angles, as seen in the diagram at left. Any planar cross-section passing through the center of an ellipsoid forms an ellipse on its surface, a cross-section of a cylinder is a circle if the cross-section is parallel to the cylinders base, or an ellipse with non-zero eccentricity if it is neither parallel nor perpendicular to the base. If the cross-section is perpendicular to the base it consists of two line segments unless it is just tangent to the cylinder, in which case it is a single line segment. A cross section of a polyhedron is a polygon, if instead the cross section is taken for a fixed value of the density, the result is an iso-density contour. For the normal distribution, these contours are ellipses, a cross section can be used to visualize the partial derivative of a function with respect to one of its arguments, as shown at left. In economics, a function f specifies the output that can be produced by various quantities x and y of inputs, typically labor. The production function of a firm or a society can be plotted in three-dimensional space, also in economics, a cardinal or ordinal utility function u gives the degree of satisfaction of a consumer obtained by consuming quantities w and v of two goods. Cross sections are used in anatomy to illustrate the inner structure of an organ. A cross section of a trunk, as shown at left, reveals growth rings that can be used to find the age of the tree. Cavalieris principle states that solids with corresponding sections of equal areas have equal volumes. The cross-sectional area of an object when viewed from an angle is the total area of the orthographic projection of the object from that angle. For example, a cylinder of height h and radius r has A ′ = π r 2 when viewed along its central axis, a sphere of radius r has A ′ = π r 2 when viewed from any angle. For a convex body, each ray through the object from the viewers perspective crosses just two surfaces, descriptive geometry Exploded view drawing Graphical projection Plans
2.
Hull (watercraft)
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The hull is the watertight body of a ship or boat. Above the hull is the superstructure and/or deckhouse, where present, the line where the hull meets the water surface is called the waterline. The structure of the hull varies depending on the vessel type, the uppermost continuous deck may be called the upper deck, weather deck, spar deck, main deck, or simply deck. The particular name given depends on the type of ship or boat. In a typical wooden sailboat, the hull is constructed of wooden planking, supported by transverse frames and bulkheads, often but not always there is a centerline longitudinal member called a keel. In fiberglass or composite hulls, the structure may resemble wooden or steel vessels to some extent, in many cases, composite hulls are built by sandwiching thin fiber-reinforced skins over a lightweight but reasonably rigid core of foam, balsa wood, impregnated paper honeycomb or other material. The shape of the hull is entirely dependent upon the needs of the design, shapes range from a nearly perfect box in the case of scow barges, to a needle-sharp surface of revolution in the case of a racing multihull sailboat. Hulls come in varieties and can have composite shape, but are grouped primarily as follows. Examples are the flat-bottom, v-bottom, and multi-bottom hull and these types have at least one pronounced knuckle throughout all or most of their length. These hull shapes all have smooth curves, examples are the round bilge, semi-round bilge, and s-bottom hull. After this they can be categorized as, Displacement The hull is supported exclusively or predominantly by buoyancy, vessels that have this type of hull travel through the water at a limited rate that is defined by the waterline length. They are often, though not always, heavier than planing types, planing The planing hull form is configured to develop positive dynamic pressure so that its draft decreases with increasing speed. The dynamic lift reduces the surface and therefore also the drag. They are sometimes flat-bottomed, sometimes V-bottomed and more rarely, round-bilged, the most common form is to have at least one chine, which makes for more efficient planing and can throw spray down. Planing hulls are more efficient at speeds, although they still require more energy to achieve these speeds. An effective planing hull must be as light as possible with flat surfaces that are consistent with sea keeping. Sail boats that plane must also sail efficiently in displacement mode in light winds, semi-displacement, or semi-planing The hull form is capable of developing a moderate amount of dynamic lift, however, most of the vessels weight is still supported through buoyancy. At present, the most widely used form is the round bilge hull, in the inverted bell shape of the hull, with a smaller payload the waterline cross-section is less, hence the resistance is less and the speed is higher
3.
Smooth curve hull
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Smooth curve hulls are hulls that are rounded and dont usually have any chines or corners. They can be moulded, round-bilged or soft-chined, examples are the round bilge, semi-round bilge and s-bottom hull. The round bilge hull is the most commonly used hull form as the shape promotes planing and has good properties as well. The S-bottom hull allows relative comfort on the boat, as the shape reduces the rolling movement on the boat
4.
Plywood
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Plywood is a sheet material manufactured from thin layers or plies of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is a wood from the family of manufactured boards which includes medium-density fibreboard. All plywoods bind resin and wood fibre sheets to form a composite material, there is usually an odd number of plies, so that the sheet is balanced—this reduces warping. Because plywood is bonded with grains running against one another and with an odd number of composite parts, the word ply derives from the French verb plier, to fold, from the Latin verb plico, from the ancient Greek verb πλέκω. In 1797 Samuel Bentham applied for patents covering several machines to produce veneers, in his patent applications, he described the concept of laminating several layers of veneer with glue to form a thicker piece – the first description of what we now call plywood. Samuel Bentham was a British naval engineer with many shipbuilding inventions to his credit. Veneers at the time of Bentham were flat sawn, rift sawn or quarter sawn, i. e. cut along or across the log manually in different angles to the grain and thus limited in width and length. One can thus presume that rotary lathe plywood manufacture was a process in France in the 1860s. Plywood was introduced into the United States in 1865 and industrial production started shortly after, in 1928, the first standard-sized 4 ft by 8 ft plywood sheets were introduced in the United States for use as a general building material. Artists use plywood as a support for paintings to replace traditional canvas or cardboard. Ready-made artist boards for oil painting in three-layered plywood were produced, in India, plywood is more commonly called Kitply after a leading brand which pioneered the concept of waterproof plywood in the early 1970s. A typical plywood panel has face veneers of a higher grade than the core veneers, the principal function of the core layers is to increase the separation between the outer layers where the bending stresses are highest, thus increasing the panels resistance to bending. As a result, thicker panels can span greater distances under the same loads, in bending, the maximum stress occurs in the outermost layers, one in tension, the other in compression. Bending stress decreases from the maximum at the layers to nearly zero at the central layer. Shear stress, by contrast, is higher in the center of the panel, the most common dimension is 1.2 by 2.4 metres or the slightly larger imperial dimension of 4 feet ×8 feet. Plies vary in thickness from 1.4 mm to 4.3 mm, the number of plies—which is always odd—depends on the thickness and grade of the sheet. Roofing can use the thinner 5/8 plywood, subfloors are at least 3/4 thick, the thickness depending on the distance between floor joists. T&G plywood is usually found in the 1/2 to 1 range, hardwood plywood is made out of wood from angiosperm trees and used for demanding end uses
5.
Fiberglass
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Fiberglass is a type of fiber-reinforced plastic where the reinforcement fiber is specifically glass fiber. The glass fiber may be arranged, flattened into a sheet. The plastic matrix may be a polymer matrix – most often based on thermosetting polymers such as epoxy, polyester resin. The glass fibers are made of various types of glass depending upon the fiberglass use and these glasses all contain silica or silicate, with varying amounts of oxides of calcium, magnesium, and sometimes boron. To be used in fiberglass, glass fibers have to be made very low levels of defects. Fiberglass is a lightweight material and is used for many products. Although it is not as strong and stiff as composites based on fiber, it is less brittle. Its bulk strength and weight are also better than many metals, other common names for fiberglass are glass-reinforced plastic, glass-fiber reinforced plastic or GFK. Because glass fiber itself is referred to as fiberglass, the composite is also called fiberglass reinforced plastic. This article will adopt the convention that fiberglass refers to the glass fiber reinforced composite material. A patent for this method of producing glass wool was first applied for in 1933, Owens joined with the Corning company in 1935 and the method was adapted by Owens Corning to produce its patented fibreglas in 1936. Originally, fibreglas was a wool with fibers entrapping a great deal of gas, making it useful as an insulator. A suitable resin for combining the fibreglass with a plastic to produce a material was developed in 1936 by du Pont. The first ancestor of modern polyester resins is Cyanamids resin of 1942, peroxide curing systems were used by then. With the combination of fiberglass and resin the gas content of the material was replaced by plastic and this reduced the insulation properties to values typical of the plastic, but now for the first time the composite showed great strength and promise as a structural and building material. Confusingly, many glass fiber composites continued to be called fiberglass, ray Greene of Owens Corning is credited with producing the first composite boat in 1937, but did not proceed further at the time due to the brittle nature of the plastic used. In 1939 Russia was reported to have constructed a boat of plastic materials. The first car to have a body was a 1946 prototype of the Stout Scarab
6.
Dugout canoe
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A dugout canoe or simply dugout is a boat made from a hollowed tree trunk. Other names for this type of boat are logboat and monoxylon, monoxylon is Greek -- mono- + ξύλον xylon -- and is mostly used in classic Greek texts. In Germany they are called einbaum, some, but not all, pirogues are also constructed in this manner. Dugouts are the oldest boats archaeologists have found, dating back about 8,000 years to the Neolithic Stone Age and this is probably because they are made of massive pieces of wood, which tend to preserve better than, e. g. bark canoes. Along with bark canoe and hide kayak, dugout boats were used by indigenous peoples of the Americas. Construction of a dugout begins with the selection of a log of suitable dimensions, sufficient wood needed to be removed to make the vessel relatively light in weight and buoyant, yet still strong enough to support the crew and cargo. Specific types of wood were often preferred based on their strength, durability, the shape of the boat is then fashioned to minimize drag, with sharp ends at the bow and stern. First the bark is removed from the exterior, before the appearance of metal tools, dugouts were hollowed out using controlled fires. The burnt wood was removed using an adze. Another method using tools is to chop out parallel notches across the span of the wood, then split out. Once hollowed out, the interior was dressed and smoothed out with a knife or adze, more primitive designs keep the trees original dimensions, with a round bottom. However, it is possible to carefully steam the sides of the hollow log until they are pliable, for travel in the rougher waters of the ocean, dugouts can be fitted with outriggers. One or two smaller logs are mounted parallel to the hull by long poles. In the case of two outriggers, one is mounted on either side of the hull, the Dufuna canoe from Nigeria is an 8000-year-old dugout, the oldest boat discovered in Africa, and the third-oldest worldwide. African Teak is the timber favoured for their construction, though this comprises a number of different species, dugouts are called pirogues in Francophone areas of Africa. A 8000-year-old dugout canoe was found by archaeologists in Kuahuqiao, Zhejiang Province and this is the earliest canoe found in Asia. The Moken, an group that lives in Myanmars Mergui Archipelago. It is now on display in front of the Municipal Town Hall, here many dugouts were made from linden wood, for several reasons
7.
Keel
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On boats and ships, keel can refer to either of two parts, a structural element that sometimes resembles a fin and protrudes below a boat along the central line, or a hydrodynamic element. As the laying down of the keel is the step in the construction of a ship, in British. Only the ships launching is considered significant in its creation. The word can also be used as a synecdoche to refer to a complete boat, a structural keel is the bottom-most structural member around which the hull of a ship is built. The keel runs along the centerline of the ship, from the bow to the stern. The keel is often the first part of a hull to be constructed. The most common type of keel is the plate keel. A form of keel found on smaller vessels is the bar keel, which may be fitted in trawlers, tugs, and smaller ferries. Where grounding is possible, this type of keel is suitable with its massive scantlings, if a double bottom is fitted, the keel is almost inevitably of the flat plate type, bar keels often being associated with open floors, where the plate keel may also be fitted. Duct keels are provided in the bottom of some vessels and these run from the forward engine room bulkhead to the collision bulkhead and are utilized to carry the double bottom piping. The piping is then accessible when cargo is loaded, the keel surface on the bottom of the hull gives the ship greater directional control and stability. In non-sailing hulls, the helps the hull to move forward. In traditional boat building, this is provided by the structural keel, in modern construction, the bar keel or flat-plate keel performs the same function. There are many types of fixed keels, including full keels, long keels, fin keels, winged keels, bulb keels, the rudimentary purpose of the keel is to convert the sideways motion of the wind when it is abeam into forward motion. A secondary purpose of the keel is to provide ballast, keels are different from centreboards and other types of foils in that keels are made of heavy materials to provide ballast to stabilize the boat. Keels may be fixed, or non-movable, or they may retract to allow sailing in shallower waters, retracting keels may pivot or slide upwards to retract, and are usually retracted with a winch due to the weight of the ballast. Since the keel provides far more stability when lowered than when retracted, types of non-fixed keels include swing keels and canting keels. Canting keels can be found on racing yachts, such as competing in the Volvo Ocean Race
8.
Canal
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Canals and navigations are human-made channels for water conveyance, or to service water transport vehicles. In the vernacular, both are referred to as canals, and in most cases, the works will have a series of dams. These areas are referred to as water levels, often just called levels. In contrast, a canal cuts across a drainage divide atop a ridge, many canals have been built at elevations towering over valleys and others water ways crossing far below. Cities need a lot of water and many canals with sources of water at a higher level can deliver water to a destination where there is a lack of water. The Roman Empires Aqueducts were such water supply canals, a navigation is a series of channels that run roughly parallel to the valley and stream bed of an unimproved river. A navigation always shares the drainage basin of the river, a vessel uses the calm parts of the river itself as well as improvements, traversing the same changes in height. A true canal is a channel that cuts across a drainage divide, most commercially important canals of the first half of the 19th century were a little of each, using rivers in long stretches, and divide crossing canals in others. This is true for many canals still in use, there are two broad types of canal, Waterways, canals and navigations used for carrying vessels transporting goods and people. These can be subdivided into two kinds, Those connecting existing lakes, rivers, other canals or seas and oceans and those connected in a city network, such as the Canal Grande and others of Venice Italy, the gracht of Amsterdam, and the waterways of Bangkok. Aqueducts, water canals that are used for the conveyance and delivery of potable water for human consumption, municipal uses, hydro power canals. Historically canals were of importance to commerce and the development, growth. In 1855 the Lehigh Canal carried over 1.2 million tons of burning anthracite coal, by the 1930s the company which built. By the early 1880s, canals which had little ability to compete with rail transport, were off the map. In the next couple of decades, coal was diminished as the heating fuel of choice by oil. Later, after World War I when motor-trucks came into their own, Canals are built in one of three ways, or a combination of the three, depending on available water and available path, Human made streams A canal can be created where no stream presently exists. Either the body of the canal is dug or the sides of the canal are created by making dykes or levees by piling dirt, stone, the water for the canal must be provided from an external source, like streams or reservoirs. Where the new waterway must change elevation engineering works like locks, lifts or elevators are constructed to raise, examples include canals that connect valleys over a higher body of land, like Canal du Midi, Canal de Briare and the Panama Canal
9.
Planing (boat)
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Planing is the mode of operation for a waterborne craft in which its weight is predominantly supported by hydrodynamic lift, rather than hydrostatic lift. The earliest documented planing sailboat was a built in 1898 by Commodore Ralph Munroe. Planing a sailing dinghy was first popularised by Uffa Fox in Britain, in 1928 Uffa Fox introduced planing to the racing world in his International 14 dinghy, Avenger. It had been designed with a shape which permitted planing. He gained 52 first places, two seconds and three third places out of 57 race starts that year and this performance was noticed by other designers who took on his ideas and developed them. Over the years many dinghies have acquired the ability to plane, advances in building materials have allowed for lighter boats which will plane faster and in lighter air. There are now many high-performance dinghies which will plane to windward, when it is at rest, a vessels weight is borne entirely by the buoyant force. At low speeds every hull acts as a displacement hull, meaning that the buoyant force is responsible for supporting the craft. As speed increases, hydrodynamic lift increases as well, in contrast, the buoyant force decreases as the hull lifts out of the water, decreasing the displaced volume. At some speed, lift becomes the predominant upward force on the hull, a simple model of this effect is a solid slab of material which is heavier than water but is shaped and oriented to have a positive angle of attack. At rest, the slab will sink because it is heavier than water, however, if the slab is kept in the same orientation and pulled horizontally through the water, it will force the incoming water downward. This results in a reactionary force upward on the slab, at a high enough speed, this reactionary force is larger than the force of gravity and the slab will stay afloat. In this way, the force is converted into a vertical force upwards. The concept of planing is often interpreted as analogous with aerodynamic lift, although any hull will plane if enough power is provided and enough speed is attained, a hull designed for operation in the planing realm is sometimes distinguished by a flat run aft. In other words, in view, the bottom is more or less a straight line towards the stern. In contrast, in a displacement, or non-planing hull, the bottom is curved in side view all the way from bow to stern, in order to minimize wave drag. All boat designs for planing benefit from minimised weight, planing powerboats are commonly made from light alloy or use other reduced-weight construction techniques- RIBs are typical examples, planing sailing boats need a good sail area and powerboats need a high-power engine. Steps and chine ridges may also be incorporated into the design to both ease of planing and stability
10.
Scow
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A scow, in the original sense, is a flat-bottomed boat with a blunt bow, often used to haul bulk freight, cf. barge. The etymology of the word is from the Dutch schouwe, meaning such a boat, Sailing scows have significant advantages over the traditional deep keel sailing vessels that were common at the time the sailing scow was popular. The cost of this shallow water advantage was the loss of the seaworthiness of flat bottomed scow boats in open water, the squared off shape and simple lines of a scow make it a popular choice for simple home-built boats made from plywood. Phil Bolger and Jim Michalak, for example, have designed a number of sailing scows, and the PD Racer. Generally these designs are created to minimize waste when using standard 4-foot by 8-foot sheets of plywood, the scow hull is also the basis for the Shantyboat or, on the Chesapeake, the Ark, a cabin houseboat once common on American rivers. The ark was used as housing by Chesapeake watermen, who followed, for example. See also the Thames sailing barge and the Norfolk wherry, two British equivalents to the scow schooner, the Thames sailing barges, while used for similar tasks, used significantly different hull shapes and rigging. The term scow is used in and around the west Solent for a class of sailing dinghy. Various towns and villages claim their own variants, they are all around 11 feet in length and share a lug sail, pivoting centre board, small foredeck and a square transom with a transom hung rudder. Originally an American design, also used widely in New Zealand, scow schooners had a broad, shallow hull, and used centreboards, bilgeboards or leeboards rather than a deep keel. The broad hull gave them stability, and the retractable foils allowed them to even heavy loads of cargo in waters far too shallow for keelboats to enter. The squared off bow and stern allowed the maximum amount of cargo to be carried in the hull, the smallest sailing scows were sloop rigged, but otherwise similar in design. The scow sloop eventually evolved into the inland lake scow, a type of fast racing boat, the American scow design was copied and modified in New Zealand by early immigrant settlers to Auckland in the 1870s. He commissioned a shipbuilder, one Septimus Meiklejohn to construct a small flat-bottomed sailing barge named the Lake Erie which was built at Omaha. The Lake Erie was 60 feet 6 inches in length, seventeen feet 3 inches in breadth and had a draught of three feet 4 inches. This one small craft spawned a fleet of sailing scows that were to become associated with the gum trade. Scows came in all manner of shape and sizes and all manner of sailing rigs and they were designed for hard work and heavy haulage and they did their job remarkably well. They took cattle north from the stockyards of Auckland and returned with a cargo of logs, sacks of kauri gum, shingle, firewood
