Naval architecture , or naval engineering , is an engineering discipline incorporating elements of mechanical, electrical, electronic, software and safety engineering as applied to the engineering design process , shipbuilding , maintenance, and operation of marine vessels and structures. Naval architecture involves basic and applied research, design, development, design evaluation (classification) and calculations during all stages of the life of a marine vehicle. Preliminary design of the vessel, its detailed design, construction , trials , operation and maintenance, launching and dry-docking are the main activities involved. Ship design calculations are also required for ships being modified (by means of conversion, rebuilding, modernization, or repair ). Naval architecture also involves formulation of safety regulations and damage-control rules and the approval and certification of ship designs to meet statutory and non-statutory requirements.
32-460: In naval architecture , a poop deck is a deck that forms the roof of a cabin built in the rear, or " aft ", part of the superstructure of a ship . The name originates from the French word for stern , poupe , from Latin puppis . Thus the poop deck is technically a stern deck , which in sailing ships was usually elevated as the roof of the stern or "after" cabin, also known as
64-454: A floating structure they will need to be calculated for all six motions and for all relative wave headings. Ship motions are important for determining dynamic loading on the crew, passengers, ship system components, secured cargo, and structural elements. Excessive ship motions may hinder the vessel's ability to complete its mission such as the deployment and recovery of small boats or aircraft. A measure of an individual's ability to complete
96-482: A given amount of exposure time. A commonly accepted limit of MSI is 20% occurrence of sea sickness over a four-hour exposure period. A small percentage of people are very susceptible to sea sickness and become ill even in the slightest conditions, while other people rarely get sea sick despite severe conditions. It has also been shown that most people acclimate to ship motions within a period of about four days, but some never acclimate at all. Seakeeping directly impacts
128-406: A means of transportation on water . The principal elements of naval architecture are detailed in the following sections. Hydrostatics concerns the conditions to which the vessel is subjected while at rest in water and to its ability to remain afloat. This involves computing buoyancy , displacement , and other hydrostatic properties such as trim (the measure of the longitudinal inclination of
160-524: A specific task while on board a moving ship is the motion-induced interruptions (MII). It gives an indication of the number of events in which a standing person will look for support in order to maintain balance. MII is measured in occurrences per hour. Ship motions have physiological effects on ship passengers and crew. The magnitudes and accelerations of ship motions, (particularly heave, roll and pitch ) have adverse effects on passengers and shipboard personnel. Sea sickness will have negative effects on
192-427: A vessel's shape was judged by looking at a half-model of a vessel or a prototype. Ungainly shapes or abrupt transitions were frowned on as being flawed. This included rigging, deck arrangements, and even fixtures. Subjective descriptors such as ungainly , full , and fine were used as a substitute for the more precise terms used today. A vessel was, and still is described as having a ‘fair’ shape. The term ‘fair’
224-494: Is being applied to predict the response of a floating body in a random sea. Due to the complexity associated with operating in a marine environment, naval architecture is a co-operative effort between groups of technically skilled individuals who are specialists in particular fields, often coordinated by a lead naval architect. This inherent complexity also means that the analytical tools available are much less evolved than those for designing aircraft, cars and even spacecraft. This
256-444: Is due primarily to the paucity of data on the environment the marine vehicle is required to work in and the complexity of the interaction of waves and wind on a marine structure. A naval architect is an engineer who is responsible for the design, classification, survey, construction, and/or repair of ships, boats, other marine vessels, and offshore structures, both commercial and military, including: Some of these vessels are amongst
288-509: Is equal to the weight of the body, in other words, the mass of the body is equal to the mass of the water displaced by the body. This adds an upward force to the body by the amount of surface area times the area displaced in order to create an equilibrium between the surface of the body and the surface of the water. The stability of a ship under most conditions is able to overcome any form or restriction or resistance encountered in rough seas; however, ships have undesirable roll characteristics when
320-504: Is important to pre-determine the behavior of the ship or floating structure when it is subjected to waves. This can be calculated, found through physical model testing and ultimately measured on board the vessel. Calculations can be performed analytically for simple shapes like rectangular barges, but need to be calculated by computer for any realistic shaped ship. The results of some of these calculations or model tests are transfer functions called response amplitude operators (RAOs). For
352-475: Is meant to denote not only a smooth transition from fore to aft but also a shape that was ‘right.’ Determining what is ‘right’ in a particular situation in the absence of definitive supporting analysis encompasses the art of naval architecture to this day. Modern low-cost digital computers and dedicated software , combined with extensive research to correlate full-scale, towing tank and computational data, have enabled naval architects to more accurately predict
SECTION 10
#1732773257045384-460: Is said to be very seaworthy and is able to operate effectively even in high sea states . In 1976, St. Denis suggested four principal terms needed to describe a seakeeping performance. These are: A drillship and a ferry have different missions and operate in different environments. The performance criteria will be different as well. Both may be considered seaworthy, although for different reasons based on different criteria. In ship design it
416-426: Is sturdy enough to hold itself together the main force it has to overcome is longitudinal bending creating a strain against its hull, its structure must be designed so that the material is disposed as much forward and aft as possible. The principal longitudinal elements are the deck, shell plating, inner bottom all of which are in the form of grillages, and additional longitudinal stretching to these. The dimensions of
448-463: The structural design drawings or models, followed by erection and launching . Other joining techniques are used for other materials like fibre reinforced plastic and glass-reinforced plastic . The process of construction is thought-out cautiously while considering all factors like safety, strength of structure, hydrodynamics, and ship arrangement. Each factor considered presents a new option for materials to consider as well as ship orientation. When
480-442: The "poop cabin" (or simply the poop ). On sailing ships, the helmsman would steer the craft from the quarterdeck , immediately in front of the poop deck. At the stern, the poop deck provides an elevated position ideal for observation . While the main purpose of the poop is adding buoyancy to the aft, on a sailing ship the cabin was also used as an accommodation for the shipmaster and officers. On modern, motorized warships ,
512-480: The United States are accredited with Naval Architecture & Marine Engineering programs. The United States Naval Academy is home to one of the most knowledgeable professors of Naval Architecture; CAPT. Michael Bito, USN. Seakeeping Seakeeping ability or seaworthiness is a measure of how well-suited a watercraft is to conditions when underway. A ship or boat which has good seakeeping ability
544-505: The ability of crew to accomplish tasks and maintain alertness and will obviously distress passengers. An important metric in evaluating sea sickness is the motion sickness incidence (MSI). The most important study on MSI was published in Aerospace Medicine by O'Hanlon and McCauley in 1974, which established common subjective thresholds of MSI tolerance. MSI is measured in percentage of people who experience sea sickness during
576-448: The ability to bring together the often-conflicting demands of the various design constraints to produce a product which is fit for the purpose. In addition to this leadership role, a naval architect also has a specialist function in ensuring that a safe, economic, environmentally sound and seaworthy design is produced. To undertake all these tasks, a naval architect must have an understanding of many branches of engineering and must be in
608-517: The balance of oscillations in roll is two times that of oscillations in heave, thus causing the ship to capsize. Structures involves selection of material of construction, structural analysis of global and local strength of the vessel, vibration of the structural components and structural responses of the vessel during motions in seaway . Depending on type of ship, the structure and design will vary in what material to use as well as how much of it. Some ships are made from glass reinforced plastics but
640-421: The body known as the hydrostatic pressures. The forces acting on the body must be of the same magnitude and same line of motion in order to maintain the body at equilibrium. This description of equilibrium is only present when a freely floating body is in still water, when other conditions are present the magnitude of which these forces shifts drastically creating the swaying motion of the body. The buoyancy force
672-402: The center of gravity and the longitudinal meta-center. In other words, the basis in which the ship maintains its center of gravity is its distance set equally apart from both the aft and forward section of the ship. While a body floats on a liquid surface it still encounters the force of gravity pushing down on it. In order to stay afloat and avoid sinking there is an opposed force acting against
SECTION 20
#1732773257045704-465: The design of a vessel. Ship motions are considered when determining the principal dimensions of the ship and in developing the general arrangements of the ship's internal spaces. For example, in most vessels the far forward parts of the ship experience the worst ship motions and are commonly unacceptable for berthing passengers or crew. In exceptional cases where ship motions pose a threat to crew, structure or machinery, or when ship motions interfere with
736-485: The forefront of high technology areas. He or she must be able to effectively utilize the services provided by scientists, lawyers, accountants, and business people of many kinds. Naval architects typically work for shipyards , ship owners, design firms and consultancies, equipment manufacturers, Classification societies , regulatory bodies ( Admiralty law ), navies , and governments. A small majority of Naval Architects also work in education, of which only 5 universities in
768-484: The largest (such as supertankers ), most complex (such as aircraft carriers ), and highly valued movable structures produced by mankind. They are typically the most efficient method of transporting the world's raw materials and products. Modern engineering on this scale is essentially a team activity conducted by specialists in their respective fields and disciplines. Naval architects integrate these activities. This demanding leadership role requires managerial qualities and
800-477: The longitudinal by about 3 or 4 meters, with the wide spacing this causes the traverse strength needed by displacing the amount of force the bulkheads provide. Arrangements involves concept design , layout and access, fire protection , allocation of spaces, ergonomics and capacity . Construction depends on the material used. When steel or aluminium is used this involves welding of the plates and profiles after rolling , marking, cutting and bending as per
832-407: The performance of a marine vehicle. These tools are used for static stability (intact and damaged), dynamic stability, resistance, powering, hull development, structural analysis , green water modelling, and slamming analysis. Data are regularly shared in international conferences sponsored by RINA , Society of Naval Architects and Marine Engineers (SNAME) and others. Computational Fluid Dynamics
864-478: The ship are in order to create enough spacing between the stiffeners in prevention of buckling. Warships have used a longitudinal system of stiffening that many modern commercial vessels have adopted. This system was widely used in early merchant ships such as the SS Great Eastern , but later shifted to transversely framed structure another concept in ship hull design that proved more practical. This system
896-454: The ship functions which were once carried out on the poop deck have been moved to the bridge , usually located in a superstructure. This article related to shipbuilding is a stub . You can help Misplaced Pages by expanding it . Naval architecture The word "vessel" includes every description of watercraft , mainly ships and boats , but also including non-displacement craft, WIG craft and seaplanes , used or capable of being used as
928-519: The strength of the structure is considered the acts of ship collision are considered in the way that the ships structure is altered. Therefore, the properties of materials are considered carefully as applied material on the struck ship has elastic properties, the energy absorbed by the ship being struck is then deflected in the opposite direction, so both ships go through the process of rebounding to prevent further damage. Traditionally, naval architecture has been more craft than science. The suitability of
960-463: The vast majority are steel with possibly some aluminium in the superstructure. The complete structure of the ship is designed with panels shaped in a rectangular form consisting of steel plating supported on four edges. Combined in a large surface area the Grillages create the hull of the ship , deck, and bulkheads while still providing mutual support of the frames. Though the structure of the ship
992-403: The vessel) and stability (the ability of a vessel to restore itself to an upright position after being inclined by wind, sea, or loading conditions). While atop a liquid surface a floating body has 6 degrees of freedom in its movements, these are categorized in either translation or rotation. Longitudinal stability for longitudinal inclinations, the stability depends upon the distance between
Poop deck - Misplaced Pages Continue
1024-529: Was later implemented on modern vessels such as tankers because of its popularity and was then named the Isherwood System . The arrangement of the Isherwood system consists of stiffening decks both side and bottom by longitudinal members, they are separated enough so they have the same distance between them as the frames and beams. This system works by spacing out the transverse members that support
#44955