Load line and its elements. Load line and recess marks. Questions for self-control
Waterline marked on the hull of a ship (in black)
Waterline(English waterline) - the line of contact between the calm surface of the water and the hull of a floating vessel. Also, in the theory of a ship, there is an element of a theoretical drawing: a section of the hull by a horizontal plane.
The following waterlines are distinguished:
The effective waterline is determined by the shape of the vessel, its average density, as well as the degree of roughness of the water in this pool. The waterline area is used to calculate the hull fullness factor. The shape of the waterline area, more precisely its moment of inertia, is a factor that determines the stability of the shape. Obviously, depending on the load conditions, heel and trim, the shape of the waterline area, and with it the stability, can change.
The length along the waterline serves as a characteristic linear dimension in determining the Froude number for displacement vessels and, accordingly, their theoretical speed.
Load line
Load line (Plimsoll line)
All commercial vessels must have a mark on board entitled load line(also known as English Load line, Plimsoll line).
Before this mark became mandatory (the first precedent in modern history was the British Load Line Act of 1890, under which the minimum permissible freeboard was set not by the shipowner, but by a government agency), many ships were lost. The main reason is overload due to the desire to obtain additional profit from transportation, which was aggravated by the difference in water density - depending on its temperature and salinity, the vessel’s draft can vary significantly.
Load line- this is a mark specially applied to the midships of the ship, by which the supercargo (the person responsible for loading, delivering and unloading cargo) determines the level to which the ship can be safely loaded, that is load waterline. When loading the vessel, it sits deeper in the water and the mark drops closer to the surface of the water.
In the 1870s, British politician Samuel Plimsoll proposed a system of universal ship markings, which made it possible to determine the maximum load of a ship depending on the time of year and region.
Table of correspondence between the vessel's draft and its loading and the load line risk
The letters on the load line mean:
Notes
Literature
Waterline:
- // Encyclopedic Dictionary of Brockhaus and Efron: in 86 volumes (82 volumes and 4 additional). - St. Petersburg. , 1890-1907.
- Suvorov N. S., Ivanov V. P., Fedorov V. P. Modern warships. - DOSAAF USSR, 1978. - 285 p.
- Fried E. G. Vessel structure. - L.: Shipbuilding, 1989. - 344 p. - 25,000 copies.
- Control over the landing of the vessel during operation is carried out according to brands of recesses .).
In contrast to settlement, which is measured from the theoretical main plane of the OP (i.e., from the inner surface of the outer skin), the recess is measured from the lower edge of the horizontal keel (i.e., takes into account its thickness
Recess marks
are applied on both sides in Arabic numerals in the area of the midship - frame, on the stem and stern in the area of the bow and stern perpendiculars and they indicate the recess in decimeters.
The layout of the recess marks on the ship's hull is shown in Fig. 3.4.
Rice. 3.4. Determination of sediment by depression grades Calculation of vessel draft by deepening marks Vessel draft T(d) is the distance measured from the OP, i.e. the upper edge of the horizontal keel to the waterline at the midships - the frame of the ship , T T(d) m and also on the nasal T(d) n and stern
ToT(d) perpendiculars. Deepening the vessel
at T(d) is the distance measured from the lower edge of the horizontal keel to the waterline, measured from the indentation marks marked on the sides of the vessel in the midship area and the bow and stern perpendiculars. T(d) perpendiculars. It is obvious that the ship's draft
T(d) m =different from the deepening of a vessel by the amount of correction and is calculated using the formulas: – δ T Well m ∙ g.k.;
T(d) n =different from the deepening of a vessel + – δ T Well n ∙ g.k.; (3.3)
T(d) is the distance measured from the OP, i.e. the upper edge of the horizontal keel to the waterline at the midships - the frame of the ship =different from the deepening of a vessel l – δ T Well is the distance measured from the OP, i.e. the upper edge of the horizontal keel to the waterline at the midships - the frame of the ship ∙ g.k.,
tgψ δ ku
Well m , Well n , Well is the distance measured from the OP, i.e. the upper edge of the horizontal keel to the waterline at the midships - the frame of the ship mu
Where
(3.4)
g.k. Well m , Well n , Well is the distance measured from the OP, i.e. the upper edge of the horizontal keel to the waterline at the midships - the frame of the ship – thickness of the horizontal keel, m;
– distances from the recess marks to the midsection and bow and stern perpendiculars, m;
Well mψ – trim angle, degrees, determined by the formula: | |||||||||||||
Well nψ – trim angle, degrees, determined by the formula: | |||||||||||||
Well is the distance measured from the OP, i.e. the upper edge of the horizontal keel to the waterline at the midships - the frame of the shipψ – trim angle, degrees, determined by the formula: |
Values
– positive if located forward of the perpendiculars and amidships and negative if located aft. These values are given in tabular form in the ship's documentation (Table 3.1). The scheme for determining sediment by depression marks is shown in Fig.
3.4.
Calculation of displacement and its geometric characteristics of the underwater part of the hull is carried out according to the theoretical drawing of the vessel during its design, and for practical calculations during the operation of the vessel - according to the ship's technical documentation, consisting of hydrostatic curves, Bonjean scale, drill, cargo scale, tables, etc.
These documents allow you to find numerical values of quantities for any
LOAD LINE(Load line, plimsoll mark) - on sea transport vessels shows the maximum draft at which a given vessel can be loaded depending on the time of year and navigation area. G.M. is the so-called Plimsoll disc. A line corresponding to the design deck is placed above the mark itself. At the ends of the horizontal line intersecting the Plimsoul disk of the international load line, letters are written indicating the classification society that carried out the calculation of the load line. Here are the most common designations:
R – S (Register of the USSR);
A – B (American Bureau of Shipping);
L – R (Lloyd's Register, UK);
R – I (Italian Maritime Register);
B – V (Bureau Veritas, France)
N – V (Norwegian Bureau Veritas).
A vertical line is drawn from the center of the disk with six horizontal lines extending from it towards the bow of the vessel. On the load line comb, in accordance with the Register rules and fully consistent with the provisions of the International Convention on Load Lines, the following is applied:
1. The line marked “L” (S) determines the maximum summer draft of the vessel in salt water. This line is drawn at the same level as the line passing through the center of the Plimsoll disc.
2. The line marked "T" (T) indicates the maximum draft for ships sailing in the tropics.
3. The line marked “P” (F) determines the maximum draft to which the vessel can be loaded in fresh water in the summer.
4. The line marked "TP" (TF) shows the maximum draft to which the ship can be loaded in fresh water in the tropics.
5. The line marked “Z” (W) indicates the maximum winter draft of the vessel.
6. The line marked “ZSA” (WNA) determines the maximum draft for winter navigation in the northern part Atlantic Ocean(north of latitude 36°).
The periods during which all these marks are valid in different parts of the world are specified in detail in the rules for affixing load lines issued by the Register.
Every seagoing vessel must be equipped load line certificate, which is issued by us by the Register on the basis of calculations made to determine the freeboard height.
LOAD SCALE(Deadweight scale) - a scale with a number of vertical columns in which the following data is graphically, on a certain scale: the number of tons per 1 cm or dm. draft, displacement, draft in m or ft, load capacity and freeboard. Using such a scale, the following issues can be easily resolved: a) determining the weight of the cargo on board the ship based on its draft; b) determining the draft of the vessel that it will have after loading a known amount of transport and utility cargo; c) determination of the change in draft from acceptance and delivery of some part of the cargo and d) determination of the freeboard of the vessel at a particular draft.
Load Line Convention(English: International Convention on Load Lines) - briefly referred to as the KGM, signed on April 5, 1966 in London at the initiative of the International Maritime Organization (IMO). In 1988, changes were made to it by a special Protocol, later, in 2003, supplemented by the IMO Maritime Safety Committee. The amended Load Line Convention (KGM-66/88) entered into force on January 1, 2005.
The Convention prohibits a vessel from going to sea in international flight unless it has been properly surveyed, has been marked with a load line and has not been issued an International Load Line Certificate or, where appropriate, an International Load Line Exemption Certificate.
The Appendices to the Convention establish the rules for determining load lines, the conditions for the purpose and amount of freeboard, modifications of the Convention requirements for zones, regions and seasonal periods, and also provide the forms of the International Load Line Certificate.
The Protocol to the Load Line Convention was adopted in 1988 and entered into force in 2000. This Protocol brought the requirements of the 1966 Convention regarding survey and issuance of International Certificates into conformity with the requirements of the International Convention for the Prevention of Pollution from Ships (MARPOL 73/78) and the International Convention for the Safety of Life at Sea (SOLAS).
Cargo characteristics of the vessel.
The cargo characteristics of the vessel include the following data about it: specific cargo capacity, coefficient of structural unevenness of holds, number and size of hatches, hatch coefficient, number of decks and their area, permissible loads on decks, number and carrying capacity of ship lifting equipment, technical means of ventilation and microclimate control in cargo areas.
Since the specific cargo capacity of a ship is related to its net cargo capacity, it can be considered a constant value only for a given net cargo capacity of the ship.
However, for practical purposes, the net tonnage can be calculated assuming 50% of the ship's stores: ∆ = ∆w -0.5Σ. Thus, the conditional net load capacity will be a constant value, which makes it possible to use the specific load capacity with sufficient accuracy.
A comparison of the specific cargo capacity with the specific loading volume of cargo allows one to judge the possibility of using the cargo capacity and cargo capacity of the vessel when loading it with one or another cargo.
For oil tankers Another qualitative characteristic of the vessel is more important - the specific carrying capacity of the tanker.
The specific carrying capacity of a tanker shows the number of tons (kg) per cubic meter of capacity. In principle, the specific cargo capacity is provided for when designing the vessel and, depending on the purpose of the vessel (for what cargo), it is distributed as follows:
Ore carriers 0.8-1.0 m3/t, bulk carriers 1.2-1.3 m3/t, container ships 1.2-4.0 m3/t, tankers 1.3-1.4 m3/t, universal vessels 1.5-1.7 m3/t, timber carriers 2.0-2.2 m3/t, ro-ro carriers 2.5-4.0 m3/t.
International Convention on Tonnage of Ships, 1969. Purpose of the Convention:
Measurement results are expressed in cubic meters;
Minimize the advantages of shelter-deck and similar vessels. The Convention introduces the following new terms and their designations:
Gross tonnage - GT in cubic meters (instead of BRT in registered tons);
Net capacity (Netto gross tonnage) - NT in cubic meters (instead of NRT in registered tons).
Under the new rules of the 1969 Convention, as well as under current rules measurements, gross tonnage GT characterizes the size of the vessel and the total volume of its premises, and the net tonnage NT is the volume of premises intended for generating commercial income. However, since the 1969 Convention affects and infringes on the commercial interests of many countries, its entry into force has been delayed.
Registered tonnage, a conditional indicator of the volume of the ship's premises protected from the sea elements. The unit of measurement is, as stated above, a registered ton, equal to 100 cubic meters. feet (2.83 m3), i.e. a registered ton is a volumetric value. Registered tonnage is used to compare the size of ships and determine the amount of various port dues, as well as for static accounting of tonnage.
Registered tonnage is divided into:
Gross tonnage is the volume of all the ship's spaces below deck and in superstructures minus the volume of: ballast tanks, wheelhouse, deck spaces for auxiliary machinery, galley, skylights, etc.
Net registered tonnage is the volume of premises used for the transport of goods and passengers, i.e. used for commercial purposes, and is used mainly to calculate port fees and taxes. It is obtained as a result of excluding the volume of residential and service premises from the gross registered tonnage
rooms, tiller and chain box, chart room, water ballast outside the double bottom space, rooms for boilers and auxiliary machinery outside the engine room.
Based on the measurement, the Register issues the vessel a document called a measurement certificate.
Number and carrying capacity of ship cargo facilities. The lifting capacity of ship booms and cranes is usually 3–10 tons. The lifting capacity of cargo booms and cranes is of great importance, as it determines the weight of the lifts, which, in turn, affects the intensity of cargo operations. Modern multi-purpose vessels are equipped with cranes with a lifting capacity of up to 35–40 tons, which allows them to independently reload containers. In addition to conventional booms, ships are armed with heavy booms with a lifting capacity of up to 60–120 tons for loading heavy cargo in ports and roadsteads.
The cargo equipment of Ro-Ro vessels should include: 2 forklifts with a capacity of 40 tons and 2 tractors for towing ro-ro cargo.
Ore carriers, bulk carriers and container ships (with the exception of feeder ships) do not have ship transshipment facilities, since they are processed mainly at specialized transshipment complexes (terminals).
Tankers have at least two cargo pumps with a capacity of at least 10% of deadweight per hour. Cargo pumps are intended only for emptying cargo from cargo tanks. Loading of tankers is carried out by shore pumps.
Unevenness of holds - capacity of individual holds sea vessels is not the same, which leads to an uneven distribution of cargo throughout the holds; when they are processed simultaneously, the largest hold limits the time for completion of cargo operations, reducing the level of intensity of cargo handling of the vessel as a whole.
The coefficient of structural unevenness of holds
The value of the coefficient fluctuates for most ships in the range of 0.6–0.9, the lower the coefficient, the lower the rate of cargo operations, therefore, the vessel's parking time for cargo operations increases.
The number and size of hatches are the most important factor determining the duration of cargo operations. The number of hatches determines how many working strokes the vessel can be loaded and unloaded, which has a decisive influence on the speed of its processing. The dimensions of the hatches determine the degree of convenience, and therefore the speed of loading and unloading; with a wide opening of the ship's deck, they significantly reduce the horizontal movement of cargo in the holds - the most labor-intensive process that limits the loading process.
The degree of convenience and adaptability of the vessel for cargo operations is characterized by the hatch coefficient, which is the ratio of the total volume of cargo spaces located under the clearance of the hatches to the total cargo capacity of the vessel.
Number of decks and their area. Permissible loads on the deck. - The depth of the hold is important on single-deck ships, as it allows the transportation of packaged cargo in several tiers and at the same time limits the transportation of cargo consisting of high cargo items. However, most general cargo has restrictions on stowage height (number of tiers) in order to protect the lower tiers from crushing. Therefore, on universal vessels, an intermediate deck is installed - a tween deck, with the help of which the cargo is protected from crushing and the pressure of the cargo on the hold deck is reduced. In addition, the tween deck increases total area cargo decks, which allows you to place on the ship large quantity volumetric cargo items (oversized), which are transported in one, maximum two tiers. For Ro-Ro vessels, deck area is the most important cargo characteristic. In order to increase the deck area, in addition to stationary decks, they are equipped with removable or suspended intermediate decks.
Permissible deck loads - number of tons per square meter. meter (t/m2) should generally correspond to the height of the cargo space:
σadd g 0.9H (t/m2),
where H is the height of the hold.
On Ro-Ro vessels, each deck must withstand at least double the TEU load, weighing 25 tons. For ore carriers, the permissible load is 18–22 tons/m2. Universal vessels: hold deck, depending on the height of the hold, is 6–12 t/m, tweendeck 3.5–4.5 t/m, upper deck 2–2.5 t/m2, cargo hatch covers 1.5– 2.0 t/m2. Timber carriers: upper deck and cargo hatch covers 4.0–4.5 t/m2. Container ships: hold deck of at least TEU weighing 25 tons in 6 tiers.
Technical means of ventilation and microclimate regulation of cargo spaces
According to the degree of equipment with technical means of ventilation, ships are divided into three groups:
Having natural forced ventilation;
Equipped with a mechanical ventilation system;
Equipped with air conditioning system in cargo areas.
On ships equipped with natural forced ventilation, air is supplied to the holds and twin-decks through a system of deflectors and air ducts.
The performance of natural forced ventilation may often be insufficient to ensure safe transportation of goods in difficult hydrometeorological conditions, especially over long distances. To increase the air exchange of cargo spaces and supply them with outside air, a mechanical ventilation system is used on ships.
Vessels with mechanical ventilation are equipped with an air distribution system and electric fans.
The air supply to the ship's hold is provided by fans, the performance of which depends on the specified air exchange rate. For ordinary universal ships, 5–7 times air change per hour is sufficient, and on ships that transport fruits, vegetables and other specific cargo, it is necessary to provide 15–20 times air change per hour.
The procedure for determining vessel loading in different zones and seasonal areas.
When drawing up a cargo plan, knowledge of the sailing conditions on the upcoming voyage and the characteristics of the cargo are important. These include data on zones and seasonal areas for determining the load line during the voyage using a map of zones and seasonal areas of load lines operating on the route during the voyage. If navigation takes place within one zone, the calculated displacement is taken to correspond to the load line established for this zone.
If during a voyage the ship crosses several zones, the estimated displacement is determined by the limiting load line on the route, taking into account voyage reserves that will be used up before approaching the area of operation of the new load line.
9. Structure of the production process in maritime transport. Technical regulation of the operation of sea transport vessels. System of indicators of fleet production activity. Carrying capacity of the vessel and fleet. Operational indicators of sea vessels. The procedure for calculating the main operational and economic indicators of the operation of sea transport vessels.
Production process structure, work processes, operations and techniques
Types of transportation.
The organization of maritime transport in each basin depends on the objectively established transport and economic relations, which determine the features, regularity and speed of cargo delivery.
Depending on what type of transport and economic relations provides sea transportation, they are divided into internal - coastal and external - foreign. Coastal transportation is divided into local, intra-regional, and external - into export and import. According to the objects of movement, sea transportation can be cargo, passenger and cargo-passenger. According to the method of implementation, sea transportation of goods is divided into transportation on ships and transportation by traction (towing).
According to transportation technology, cargo transportation is distinguished: in bulk (oil and petroleum products, vegetable oils, etc.), in bulk (ore, coal), in bulk (grain), with cargo stowed in cargo spaces and on deck (packaged and packaged cargo ), in containers and packages, ferry, car and trailer.
According to the form of organization of vessel traffic, sea transportation of goods is divided into regular (linear and sequential voyages) and irregular (cruise).
Depending on the area of navigation of ships, maritime transport can be coastal (local), sea, ocean and Arctic.
Based on the interaction of the maritime fleet with other modes of transport, cargo transportation by sea is distinguished between direct sea traffic and mixed traffic. IN direct message transportation of goods between the sender and the recipient is carried out by sea vessels. In mixed traffic, transportation is carried out when it involves not only sea vessels, but also rolling stock of other modes of transport. Transportation in direct water communication refers to those carried out by sea and river vessels.
In railway sea transport, cargo transportation is distinguished under a single transport document: cargo in ports is transferred from one type of transport to another without the participation of the cargo owner. All this allows you to speed up the movement of goods, reduce transportation costs, and organize work various types transport as a single technological process.
Production process in maritime transport. It involves the transportation of goods and passengers by sea on special vehicles- sea transport ships - and includes three phases: initial - all operations from the moment a passenger purchases a ticket or the sender presents cargo until the ship leaves the port;
the main one is the movement of cargo and passengers by ship; final - all operations from the moment the ship arrives at the port of destination until the transfer of cargo to recipients and disembarkation of passengers.
All phases of the production process, as well as the operations included in them, are interconnected. In the transport production process they successively replace each other. Their interconnection expresses the unity of the transport production process carried out by the fleet and seaports - the main production units maritime transport. Each phase is a set of operations that represents a certain completed part of the overall process
transportation of goods by sea transport. The production process in maritime transport consists of successive voyages of ships. A voyage is understood as a completed production cycle for the movement of goods or passengers by a sea transport vessel.
The production process of maritime transport is divided into technological processes of its production units.
In addition to the fleet, they are directly involved in the transportation of goods or passengers. sea ports. Other maritime transport enterprises - ship repair yards, bunker bases, auxiliary vessels - provide the work of the main enterprises with their own technological work process.
Draft grades
Draft grades (deepening grades)
marks on the outer plating in the bow, stern and middle part of the ship's hull, applied at a certain level from the keel to determine the draft of the ship. Draft marks - numbers or letters with a height and a distance between them of 100 mm. The amount of draft at the bow and stern can only be determined by knowing the distance of each draft grade from the keel (given in a special draft layout diagram)
EdwART. Explanatory Naval Dictionary, 2010
See what “Sediment marks” are in other dictionaries:
- (Draft marks) see Load line. Samoilov K. I. Marine dictionary. M. L.: State Naval Publishing House of the NKVMF of the USSR, 1941 ... Marine Dictionary
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