Any shipbuilder who plans to provide freight or passenger flows should be aware of how properly the ships are created. The organization of ships is a whole science that allows to foresee and correctly assess the behavior of a ship during its operation in any, even the most difficult situations.
What is a ship?
The vessel is a complex floating engineering structure that solves a whole series of tasks - from economic to public and special ones. Each floating facility consists of a huge number of mechanisms and units, instruments and apparatus, the integrated and stable operation of which creates ships. The construction of ships is complex and obeys the laws of physics, and is also built on the basis of modern advanced knowledge and progressive achievements. Modern vessels are presented in a huge variety, depending on the features of their design and basic characteristics. Vessels are self-propelled and non-self-propelled, floating above water, on water and under water, with different types of hulls.
Depending on the area of navigation, the ships are divided into sea, inland navigation (that is, river and lake) and mixed type, that is, those that make shipments between sea and river ports. Depending on the type of motor that drives the ship, steamers, motor ships and diesel-powered ships are allocated. Engines in ships can be screwed, with a wing propeller, propellers, the vessel can sail or paddle.
What are civil vessels?
The design of vessels engaged in civilian transportation is thought out in such a way as to ensure the normal operation of the funds, depending on their purpose. The most popular civilian vessels are transport and fishing vessels. Transport floating means are intended for transportation of passengers or cargoes, or both and simultaneously and are divided into liners and tramps. Fishing is represented in a larger number of species - fishing, whaling, floating bases, fish cannery-trawlers and so on.
Main operational properties
Each vessel has certain technical properties. They depend on such indicators as the transport capacity and economy, which show the vessels. The structure of vessels depends on such parameters:
- Load capacity: this indicator characterizes cargoes that can transport a vessel without changing the design landing; Net load is the total weight of the payload carried by the vehicle, and deadweight is the total weight of the entire cargo transported, including the volumes of fuel, boiler water, weight of luggage and crew, that is, the sum of all shipments;
- Displacement: this is the sum of all the constant weight that affects the total weight of the entire ship;
- Cargo capacity: this is the volume of all cargo spaces on the floating craft;
- Grain capacity: this is the theoretical volume of cargo spaces, in which the volume of the hull and other internal structures is not considered;
- Final capacity: this indicator indicates the conditional volume of all spaces of the ship in which the goods and passengers are carried;
- Speed: from this indicator depends the economic efficiency of the vessel and its carrying capacity;
- The range of navigation: that is, the distance that a ship can pass at a certain speed without the need to replenish stocks;
- Maneuverability: this parameter indicates the ability of the ship to perform certain maneuvers, primarily to change direction and speed;
- Autonomy of navigation: this is an indicator of the working time of a ship without replenishing fuel, water, food reserves;
- Survivability, that is, the ability of the vessel in unforeseen circumstances to complete a safe voyage.
Stability is an important indicator
The ship's theory of the vessel presupposes the attention of the stability of each floating device. This parameter is understood as the conditions under which the vessel moves in a vertical position and its straightening after inclinations. An important role is played by the correct loading of each vessel, taking into account its reliability and economy. The vessel can change its equilibrium under the influence of wind and waves, and the stability depends on the position of the metacenter in relation to the center of gravity. A true metacenter is a point at which two adjacent directions of the pushing force intersect. The moment of stability affects the straightening of the vessel until the center of gravity lies above the true metacenter. If the metacenter is lower, then the vessel will not maintain equilibrium.
How is the ship arranged?
The general arrangement of ships in the most general terms is as follows. The main element is the body, consisting of an outer skin - it serves as the basis for the bottom and side. Above, the hull is covered with deck, and there may be several depending on the type of vessel. The upper deck has a length from side to side and from the bow of the ship to its stern - on it are arranged premises for different purposes. If the deck is long - from side to side, then it is called a superstructure, if it occupies only a part of the ship - it is a felling. On some ships, even shorter decks can be attached to the upper deck - these can be boat boats, walking decks. Decks even higher have a special purpose, for example, a radio room or a central control station.
For sheathing, sheet steel of different thickness is used, while it is supported by an internal frame, which is called the ship's set. It includes transverse frame structures, longitudinal beams stringer, beams supporting the deck. In the decks hatches and cutouts can be cut out, which must be strong, for this they are finished with steel sheets and angles.
The bottom of most modern vessels is double, with internal decking. Such a thoughtful design is associated with ensuring the safety of the facility. In the double bottom space, liquid fuel, fresh water, water ballast can be stored, which level the vessel and immerse it deeper into the water. Inside the hull is divided into compartments by transverse bulkheads, thanks to which the transverse strength and unsinkability of the vessel is achieved.
Includes a number of vital elements of the vessel. The diagram shows that the ship has an engine, propulsion and steering wheel. The propeller is a device that affects the conversion of the mechanical energy of the engine into the energy of the vessel's motion. The steering wheel is needed for steering the vessel, while in the modern version it has been transformed. Let's consider some features of some ship systems in more detail.
Features of hull shape
The theory of the device of the ship proceeds from the fact that the load on it falls. The hull of the vessel is under the influence of hydrostatic pressure forces, which grow as the depth increases. Due to the pressure of seawater, the vessel is subjected to transverse loads and a load from its own volume of means, as well as the buoyancy force. As a consequence, the shape of the hull depends on the type of vessel and its destination, as well as the deadweight, the required volume of holds, the number of decks, speed and transverse stability. In addition, the shape of the hull depends on the purpose of the transport vehicle and its performance characteristics.
Shipbuilding is a laborious process, in which every detail plays a role. Modern forms of buildings significantly differ from those that were originally. And first of all the changes touched on the materials and technologies used. If initially the floating means were made of wood, then gradually it was replaced by metal, steel. An important role is played by a small weight of structures while maintaining strength. The use of welding elements for joining allowed to significantly reduce the number of structural elements and make them more lightweight and durable at the same time.
Modern floating equipment has details of mild steel and steel casting, light alloys and plastic. And plastic is widely used not only for the production of parts, but also for the creation of small vessels, for example, fishing or sports or lifeboats.
Features of the outer skin
The outer skin is the outer shell of the ship's hull, which is subject to water pressure. It depends on it depends on the strength of the case. Outer sheathing is a separate sheet, connected with each other by welding. The thickness of this layer varies and depends on the length of the ship, the height of its bead, as well as on the draft and the distance between the frames - ribs bodies, on which the shape of the particular vessel depends. The arrangement of a sea-going ship is such that the same vessel may have different thicknesses of skin at different sites. The middle part of the ship experiences greater tension, so there the thickness of the sheets is greater than in the extremities. Subject to reinforcements are the bottom set on the bow and stern of the vessel, which is due to the impact of pitching.
Deck and deck below deck
The deck is an important element of any vessel. The external structure of sea vessels from the constructive point of view is the same, where the deck is a horizontally overlapping block in the hull. The upper continuous deck is considered the main one - it forms the common shell of the vessels. All decks located below the main one are needed to increase the useful area of the vessel. The decks arranged above are called superstructures. The deck of the main deck can be of different thicknesses - this depends on the length of the ship and the height of its side.
Features of the steering device
The steering device of the vessel fulfills the main goal - to counteract the external forces, that is, the wind, the current, which can lead to deviation of ships from the course. In ancient times, instead of rudders, a swinging oars were used at the stern, then they were replaced by a hinged steering wheel, which was placed on the main deck. Today, several types of rudders are known - from the ordinary and the balancing to the bow thruster. The steering wheels are also active and passive: the latter allow you to turn the boat while the water is moving relative to the ship's hull. An active steering wheel allows you to turn both a moving and standing vessel.
The passive steering device of the vessel includes a steering wheel with a gear, a steering machine, a steering pen. In old ships, single-layered rudders have been preserved, and today mainly curved shaped rudders are used. The active steering wheel performs its functions even if the ship is not moving, that is, at anchor. The active steering wheel is widely used in equipping floating fisheries, whalers and repair ships.
To improve the maneuverability of the vessel, the ship's thruster is often used. They are mounted on the bow or stern across the floating facility in the tunnel, where two propellers are also located . This auxiliary tool is needed in order to operate the vessel at the lowest possible speed. The steering device is selected depending on what the vessel is used for: one group of rudders affects the sustainability of the course, the other helps to ensure good agility.
Anchor - an important element
The ship's anchoring is necessary in order to keep the floating craft in a certain position, when it is required to withstand external factors such as wind, waves, and current. Vessels are to anchor in the roadstead or in anticipation of entering the harbor, as well as in emergency situations. Modern anchors are represented in a wide variety and are divided into groups. For example, rod anchors rod-anchor, Trotman's anchor and Hall's anchor equip sports vessels or sailing training aids.
Anchor devices of vessels work as follows: when the anchor drops, the anchor falls to the bottom, after which it is towed by the vessel. The anchor at the movement clings "paws" behind the bottom. To raise it, an anchor chain is used: it lifts the anchor from the bottom surface, tearing it from the ground. The length of the anchor chain depends on the pressure of the wind, the shock of the wave and must assume all these external forces. The anchor device is most often located on the bow of the ship, where an anchor winch is also mounted, which operates on an electric or hydraulic drive.
A number of important details
The mooring device of vessels is necessary so that the vessel can stand at the berth during berthing in the port. Mooring is carried out by means of moorings - they stretch from vessel to shore diagonally. Today these elements are made of strong synthetic materials. When ships approach the shore, mooring ropes are thrown from them.
The general structure of the vessel is represented by numerous ship systems in the form of drying and ballast systems, heating and air conditioning. Each of them plays a role: dehumidification facilitates the diversion of water collected overboard, the ballast is needed to drain and fill the tanks with sea water, and the safety and comfort of operation of each ship depend on other systems.