The coefficients of completeness of the body are shown in fig. 2.5.

VL completeness factor α - the ratio of the area of ​​the waterline to the area of ​​the circumscribed rectangle:

where S VL is the area of ​​the waterline.

Fullness ratio midship - frame β - the ratio of the submerged area of ​​the midship frame to the area of ​​the circumscribed rectangle:

Rice. 2.5. Completeness coefficients: a - waterline area;

b - the area of ​​the midship frame; c - displacement

Coefficient general completeness δ - the ratio of the volume of the underwater part of the vessel V to the volume of the circumscribed parallelepiped:

. (2.3)

Vertical completeness factor χ - the ratio of the volume of the underwater part of the vessel to the volume of the cylinder, the area of ​​\u200b\u200bthe base of which is equal to the area of ​​the waterline ( S), and the height - the ship's draft ( T):

or or (2.4)

Longitudinal completeness coefficient φ – the ratio of the volume of the underwater part of the vessel to the volume of the cylinder, the base area of ​​\u200b\u200bwhich is equal to the area of ​​​​the midship - frame (), and the height is equal to the length of the vessel (L):

or or (2.5)

The second designations are accepted in foreign literature.

1. The ratio of the main dimensions of the vessel

The main dimensions of the ship L.V.N andT determine the dimensions, and their ratios give an idea of ​​the shape of the hull and characterize some of the seaworthiness of the vessel.

Attitude L/B gives an idea of ​​the speed of the ship, since the larger this ratio, the faster the ship.

Attitude L/H characterizes the rigidity and strength of the ship's hull, i.e. with its growth, the rigidity and strength of the hull decreases.

Attitude N/T characterizes the degree of unsinkability of the vessel and with its growth, unsinkability increases.

Attitude V/T affects the stability and propulsion of the vessel and with its growth, stability increases, but propulsion deteriorates due to an increase in water resistance.

The characteristic values ​​of the coefficients of completeness and the ratio of the main dimensions are given in Table 2.1.

Table 2.1. Completeness factors and ratio

Main dimensions of transport ships

Vessel types	L/B	V/T	N/T	L/H	δ	α
Dry cargo court			1,25-1,52	10,3-14,5	0,62-0,75	0,80-0,85	0,95-0,98
bulk carriers			1,30-1,58	10,5-14,5	0,73-0,83	0,78-0,88	0,96-0,99
tankers			1,18-1,52	11,5-14,0	0,72-0,90	0,78-0, 89	0,98-0,99
container ships			1,35-2,1	9,0-14,0	0,60-0,70	0,82-0,86	0,95-0,98
Roll-on ships			1,85-2,28	8,2-10,5	0,59-0,69	0,82-0,88	0,94-0,97

1. Theoretical drawing

The shape of the vessel is most fully determined by the theoretical drawing of the vessel - a set of projections of sections of the surface of the vessel onto three main mutually perpendicular planes of the vessel (Fig. 2.6).

Rice. 2.6. Theoretical drawing of the vessel

As the main projection planes of the theoretical drawing, they take: the diametrical plane, the main plane and the plane of the midsection - frame.

The lines of intersection of the ship's surface by planes parallel to the diametrical plane are called buttocks. The lines of intersection of the surface of the vessel with planes parallel to the main plane are called waterlines, and the lines of intersection of the surface of the vessel with planes parallel to the plane of the midship - frame - theoretical frames.

The projection of all these lines onto the diametrical (vertical) plane is called - "SIDE". The buttocks on this projection are depicted without distortion, and the waterlines and frames are visible as straight lines. The projection of the intersection lines onto the horizontal (main) plane is called " HALF-WIDTH”. The waterlines on the projection are depicted without distortion, and the buttocks and frames in the form of straight lines. Since the waterlines are symmetrical (with a symmetrical shape of the ship), they are shown at half-latitude only on one side of the DP. At half-width, the line of intersection of the upper deck and side, as well as all decks of the vessel, is depicted. The projection of all lines of intersection onto the midsection plane is called "FRAME» (profile projection). On the hull, on the right side of the DP, a projection of the bow frames is depicted, and on the left side, the stern frames. Projections of waterlines and buttocks are shown as straight lines.

A theoretical drawing is necessary for calculating seaworthiness - buoyancy, stability, unsinkability, building the ship's hull, as well as in operation - to determine the size of the premises and the distances to the holes in the ship's hull. The straight lines of a theoretical drawing are called "grid" and oblique sections "fish».

When developing a theoretical drawing of a ship, reduction scales are used: 1:200, 1:100, 1:50, 1:20, 1:10, depending on the size of the ship.

When building a ship at shipyards, some sections of the hull are drawn on a scale of 1: 1 on the floor of a special workshop called the "plaza".

Completeness of the assortment - the number of varieties of goods within the type.

The greater the completeness of the assortment, the higher the likelihood that consumer demand for goods of a certain group can be satisfied.

The increased completeness of the assortment can serve as one of the means of stimulating sales and satisfying a variety of needs due to different tastes, habits and other factors.

The assortment completeness ratio reflects the ability of goods of a homogeneous group to satisfy the same needs and is calculated by following formula:

Kp = (Pb: Pd), where Kp is the coefficient of completeness;

Pb - basic completeness, a list of goods depending on the volume of packaging in three competitive outlets;

Pd - actual fullness, the actual amount of juice products, depending on the volume of packaging, pcs.

The study revealed that when buying milk powder, consumers pay attention to such a feature as the volume of product packaging. It depends on the needs of each consumer (size and composition of the family, etc.). As a result, it is advisable to take this feature as a basis for calculating the assortment completeness ratio.

Moreover, in order to calculate the completeness coefficient, the range of products of the Troitsky Food Processing Plant brand was considered.

Calculation of the completeness indicator: Kp = (3: 5) = 0.6

In the assortment of the Vinnaya Karta outlet, consumers can find products of the Troitsky Food Plant LLC brand in far from all types of packaging, depending on its volume.

The probability that consumer demand will be fully satisfied is not very high. Such a low indicator of the completeness of the range of juice products, depending on the volume of packaging, is explained by the fact that the buyers of this store, who are mostly regular, prefer to purchase powdered milk in paper containers of a standard volume (0.5 kg).

Novelty coefficient

For many consumers, it is important to see the latest innovations in the range of outlets. This is due to the emergence of new species that are improved. So for integrated assessment assortment it is also important to determine the indicator of the novelty of the assortment.

The novelty of the assortment is the ability of a set of products to meet changing needs through new products.

The novelty indicator is defined as the number of new products in the general list. Updating the assortment is one of the directions of the assortment policy of the organization. It is carried out, as a rule, in a saturated market. The reasons that prompt the manufacturer and seller to update the range are:

Replacement of obsolete goods,

Development of new products of improved quality;

Expansion of the range through

Increase in completeness to create competitive advantages.

However, it should be borne in mind that the constant updating of the assortment is associated with a certain risk that the costs may not be justified, and new product will not be in demand. Therefore, the update must be rational.

To calculate the novelty coefficient, it is necessary to calculate the novelty indicator.

By interviewing sellers about the arrival of new products over the past 4 months, it was found that 1 new brand name of powdered milk was received.

The calculation of the novelty coefficient is performed according to the following formula:

Kn \u003d (N: Shd),

where Kn is the coefficient of novelty;

H - the number of new products that went on sale in the last 4 months;

Shd - the actual breadth of the range.

Calculation: Kn \u003d (1: 4) \u003d 0.25

The novelty coefficient for this outlet was 0.25. Such a small value of the coefficient is explained by the fact that at present the SMS market is saturated and new brands of powdered milk practically do not appear.

Updating the range of this product is mainly due to the emergence of new flavors.

Stability factor

Assortment stability is the ability of a set of products to satisfy the demand for the same products.

Among consumers there are those who rarely change their tastes and preferences throughout their lives.

To a greater extent, this category of consumers includes older people who are generally distrustful of everything new. Based on this, the task of the outlet is, among other things, to meet the demand from this category of consumers.

In the outlet under study, the Monetka store presents brands of powdered milk that are constantly in demand and are on sale. The number of stable brands in this outlet is 3. The value was given by the seller.

The assortment stability coefficient is calculated using the following formula:

Ku \u003d (U: Shd),

where Y (sustainability index) - the number of brands of juice products that are in steady demand among consumers;

Shd - the actual breadth of the range;

Ku - coefficient of stability.

Calculation:

Ku \u003d (3: 4) \u003d 0.75.

The stability coefficient of the assortment, calculated by the formula (4) was 0.75.

That is, more than half of the entire range of the Vinnaya Karta outlet is in steady demand from consumers.

It is this part of the assortment that the entrepreneur orders first of all when purchasing the next batch.

outlet you need to take into account the fact that tastes and habits change over time, so the sustainability of the assortment should be rational.

When designing the shape of a vessel, a number of experimental values ​​are taken into account - shipbuilding characteristics that determine not only the various qualities of the vessel, but also its efficiency. The shape characteristics describe the shape of the vessel and thus its appearance through the relationship between the main dimensions of length, width, side height and draft, as well as through the ratio of the area of ​​the waterlines, the area of ​​the frames and displacement with the main dimensions. Shape characteristics are usually related to structural settlement. In particular, they influence the behavior of a ship at sea, and when choosing relative values, they take into account, first of all, the requirements for a given type of ship.

Length to width ratio L/B affects mainly the speed qualities of the vessel, its maneuverability and stability. Large values L/B(long narrow vessels) favorably affect the speed of the vessel and its stability on the course. Therefore, passenger and fast cargo ships are of great importance. L/B. At a given speed and displacement under these conditions, the required engine power is reduced, and course stability is improved due to the larger lateral surface of the underwater part of the vessel (projection area). Upper bound of the ratio L/B determined by the necessary lateral stability of the vessels. In addition to these advantages, a large WT ratio makes it possible to increase the volume of the hull of passenger and large cargo ships and rationally allocate space on them. On the economy of these vessels fluctuating values L/B almost no effect. Small values L/B(short wide ships) provide good maneuverability and stability. For this reason, tugs, which must have good agility and often experience jerks with a lateral pull of the cable, which affect lateral stability, have particularly small L/B.
The ratio of the length to the height of the side L/H at a free beam (ship) is the ratio of the length of the beam to its height. This ratio is critical to the longitudinal strength and flexure of the ship's hull. small L/H, i.e., a large side height for a given length, requires smaller dimensions for the upper and lower corbels of the ship's hull and, under a longitudinal load, gives a smaller deflection than a large L/H. Smaller girdle sizes are possible as a result of the modulus required to provide longitudinal strength being favored by an increase in beam height. For this reason, long superstructures in the middle of the vessel are included in the upper belt (large side height H) vessel. For reasons of strength, and also depending on the area of ​​navigation, the following ratios are taken as the maximum allowable: with unlimited navigation L/H= 14; with a large coastal voyage - L/H= 15; for the North Sea - L/H= 16; for the Baltic Sea - L/H= 17; with small coastal navigation - L/H= 18. For inland navigation vessels that are not subject to significant waves, take significantly higher values L/H(up to 30).

Beam to draft ratio B/T determines mainly the transverse stability and resistance to the movement of the vessel. Since stability increases in proportion to the third degree of breadth, ships with a small B/T(narrow ships with a large draft) have lower initial stability than ships with a large B/T(wide vessels with shallow draft); however, the latter are prone to sharp pitching in waves. Since, for example, tugs, due to their low freeboard, are not very stable at significant inclinations, they, like all other small ships, usually have a large B/T, while large high-sided vessels have lower values B/T. The resistance to movement of ships with a large B/T more than ships with small B/T.

Height to draft ratio H/T characterizes the margin of displacement, i.e., the displacement of the unsubmerged waterproof part of the ship's hull, and to a large extent affects the angle of sunset of the static stability diagram. The more H/T, the greater the freeboard and, consequently, the buoyancy of the vessel. In addition, the angle of decline of the static stability diagram is significantly increased due to the large freeboard. Thus, ships with a large H/T, for example, passenger ships, have greater stability than ships with low H/T, since the first at high inclinations of the vessel (60 ° and more) still have a restoring moment, which significantly reduces the risk of capsizing.

Completeness coefficients

Design waterline completeness factor α - the ratio of the area of ​​\u200b\u200bKVL to the area of ​​\u200b\u200ba rectangle whose sides are equal L and AT. The smaller this coefficient, the sharper the waterline. Usually ships with large L/B(long narrow vessels) have higher DWL coefficients than short wide vessels.
midship frame fullness factor β - the ratio of the submerged area of ​​the mid-frame to the area of ​​a rectangle with sides AT and T. It is significantly influenced by the shape of the frames, as well as the rise and radius of the cheekbone. The greater the lift and the radius of the chin (for example, for small fishing vessels, tugs and icebreakers), the lower the coefficient of fullness of the midship frame.
Overall completeness coefficient δ - the ratio of the volume of the underwater part of the vessel to the volume of the body with sides L X AT X T. This coefficient to some extent characterizes the shape of the vessel in relation to sharpness and has a significant impact on displacement (carrying capacity); on the other hand, with the growth δ the ship's resistance increases. On the contrary, a ship at a given displacement becomes longer as the weight ratio decreases, without becoming heavier, since the required engine power at a given speed decreases, as a result of which the need for fuel becomes less. Such a vessel will be more cost-effective also because it is longer and, therefore, may have more holds.

Longitudinal completeness coefficient φ - the ratio of displacement to the volume of the body, the base of which is the area of ​​​​the midship frame, and the height is the length of the vessel. This coefficient is always slightly larger than the overall weight coefficient and better characterizes the sharpness of the ship's extremities. A large coefficient of fullness of the midship frame means the full ends of the vessel, a small one - on the contrary, narrow ones. However, when comparing two vessels, one must always take into account the ratio L/B. At large L/B(long narrow ships) midship frame or overall weight coefficients may be greater than with small L/B(short wide vessels); while the contours do not become fuller.

The recall factors mentioned above are interrelated and therefore cannot be chosen arbitrarily. The listed characteristics of the form (relative values ​​and coefficients of completeness) largely determine the behavior of the vessel at sea, the resistance to movement and the profitability of the vessels and, moreover, mutually influence each other.

4.4.3 Drag - Froude number

When moving, waves are created at the bow and stern of the vessel, which become larger with increasing speed. This is explained by the fact that with an increase in the speed of movement, a significant rarefaction occurs in the stern of the vessel, and a zone of high pressure occurs in the bow. The energy expended on the formation of waves is the wave resistance, the value of which is determined by the speed and length of the vessel. A characteristic of the ship's wave resistance is the ratio of speed to length, called the Froude number:

fr= v / √gL

This characteristic makes it possible to compare ships of different sizes, which makes it possible to determine the resistance and thus the engine power for a ship under construction using model towing tests. The vessel and model speeds are related as the square roots of their linear dimensions:

This means, for example, that a ship under construction with a length of 130 m, a width of 14 m, a draft of 6.6 m, a displacement of 5900 tons and a speed of 25 knots (12.86 m/s) corresponds to a model speed of 2.572 m/s with a length of 5, 2 m. At this speed, the model has a wave formation, which is geometrically similar to the wave formation of a full-scale ship. The resistance measured in this case, however, contains not only wave resistance, but also another component - frictional resistance, which arises as a result of the braking effect of water flowing past the housing. Friction resistance depends on the area of ​​the wetted surface of the body, on its quality (degree of roughness) and on the speed. It can be calculated with sufficient accuracy from experimental data both for the model and for the ship. If the impedance of the model is reduced by the calculated coefficient of friction, the wave drag of the model will be obtained. When recalculating, the provision applies that the wave resistances of two similar geometric bodies - the vessel and the model - are related as their displacements. But this simple relationship is only valid when the ship and the model are moving at comparable speeds, so that geometrically similar wave formations occur. If we add the calculated friction resistance to the wave resistance (determined by experiments on the model), we get the total resistance of the vessel. In our example, during model tests, a wave resistance of 0.31 MN was determined and, by calculation, a friction resistance of 0.35 MN. The ship's total drag is thus 0.66 MN. Of course, in the final determination of the required engine power, air and vortex resistances must also be taken into account.

The proportion of wave drag and friction drag in total drag depends on the shape of the ship and its speed. For large, slow-moving vessels, the wave resistance is approximately 20%, and for very high-speed vessels, up to 70% of the total resistance. Ship load components

The displacement of a ship is the mass of the volume of water in tons displaced by the hull to the permissible load waterline, which, according to the law of Archimedes, is equal to the mass of the ship. The mass of the vessel is the sum of the own mass of the vessel and its carrying capacity (mass of the payload).

The empty weight of the vessel includes:

Vessel hull equipped with inventory and spare parts; ready for operation power plant with inventory and spare parts; water in boilers, pipelines, pumps, condensers, coolers;

Fuel in all operational pipelines;

Carbon dioxide and brine or other operating materials in refrigeration and fire fighting systems;

Residual water in bilges and tanks that cannot be removed by pumps, as well as sewage and moisture.

Carrying capacity in tons with the volume of holds and operating speed is the most important economic characteristic vessel; it must be guaranteed by the shipyard, as understating it is punishable by contractual penalties. Gross tonnage - ship's deadweight - includes all masses that are not related to the ship's lightship displacement, such as:

Payload (including mail);

Crew and passengers with luggage;

All operating materials (fuel reserves, lubricants, oils, boiler feed water) in storage tanks;

Ship supplies such as paints, kerosene, wood, resin, ropes;

Supplies for crew and passengers ( drinking water, water for washing and provisions);

Cargo securing equipment such as wooden braces, tarpaulins and masts, longitudinal semi-bulkheads for bulk cargo;

Special equipment for special types of vessels, such as fishing equipment (nets, cables, trawls).

There are certain relationships between the most important components of the load, which also affect the efficiency of ships.
The ratio of the ship's displacement when light to displacement when fully loaded depends mainly on the type of ship, the area of ​​navigation, the speed of the ship, and the design of the hull. So, for example, the displacement of a light cargo ship at normal operating speed (14-16 knots) without ice reinforcements is approximately 25% of the displacement in a full load. At the icebreaker, which must have powerful engines and a specially reinforced hull, the empty displacement is approximately 75% of the total displacement. If a cargo ship has a total displacement of 10 thousand tons, then the empty displacement is approximately 2.5 thousand tons, and its deadweight is approximately 7.5 thousand tons, while big icebreaker the same displacement has an empty displacement of approximately 7.5 thousand tons and a deadweight of 2.5 thousand tons.

Mass ratio power plant to full displacement is determined by the speed of the vessel, the type of engine (diesel, steam turbine, diesel-electric plant, etc.), as well as the type of vessel. Increasing the speed of the vessel with the same type of installation always leads to an increase in engine power and, consequently, to an increase in these ratios.

Ships with a diesel engine have a larger engine weight than ships with other types of engines. Since the power plant also includes auxiliary machinery for the production electrical energy and power plants of refrigerators, then the mass of power plants of passenger, refrigerator and fishing vessels is greater than the mass of units of conventional cargo ships of the same displacement. Thus, the mass of the power plant of cargo ships is 5-10%, passenger ships - 10-15%, fishing vessels 15-20%, and tugs and icebreakers, as a rule, even 20-30% of the total displacement.

The ratio of the mass of the hull to the displacement is determined by the mass of the bare hull of the vessel and the mass of its equipment. All these masses depend on the type of vessel and, therefore, on its purpose. The mass of the ship's hull is affected not only by its main dimensions and their ratios, but also by the volume of superstructures and ice reinforcements. The recruitment system and application also play a significant role. structural steels high strength, especially for vessels over 160 m in length.

The mass of equipment depends on the purpose of the vessel; for example, for passenger ships due to passenger cabins, public, utility rooms, etc. or for fishing ships (fishing and processing) due to crew cabins, fish processing machines and refrigerator equipment, it is significantly larger than for ordinary cargo ships and tankers.

The ratio of deadweight to gross displacement (dwt utilization ratio) best characterizes the efficiency of cargo ships (not to mention the speed of the vessel). For tugs and icebreakers, the deadweight primarily determines the cruising range (duration of the voyage), since the deadweight of ships of these types is spent mainly on fuel materials and supplies.

Cargo ships and tankers (from 60 to 70%) have the largest deadweight utilization rate, tugboats and icebreakers have the smallest (from 10 to 30%).

4.4.4 Features of the shape of the ship's hull

The shape of the ship's hull is determined by its type and purpose. Deadweight, the required volume of holds, the number of decks, speed and lateral stability have a significant impact on the shape. Along with this, the shape of the hull may be affected by limitations in length, height and draft associated with the size of locks and bridge spans, with the depth of fairways, as well as with the need to solve special tasks (for example, towing or icebreaking).

The shape of the underwater part of the hull up to the design waterline is determined by the ratios of the main dimensions and the coefficients of completeness, and a compromise solution is often inevitable. Thus, for cargo ships, it is customary to adopt not those coefficients of gravity that are necessary to obtain the minimum power of the main engines and fuel reserves, but higher coefficients of gravity in order to obtain a greater carrying capacity. Only for high-speed cargo ships (for example, refrigerator ships) are small, i.e. favorable, coefficients of completeness taking into account their speed qualities.

As a rule, the shape of the vessel is selected as follows. The structural waterline forms an angle in the fore end with the diametrical plane, the value of which, depending on the weight of the ship, is 10-25°. At the aft end, this angle is taken to avoid separation of vortices, 18-20 °. In the stern below the design waterline, for twin-screw ships, the frames are V-shaped, and for single-screw ships, U-shaped, in order to get the maximum favorable conditions flow around the propeller. In the region of the cruising stern, the frames are made in such a way that they do not cross the design waterline very flatly, so that with a slight increase in draft (with trim to the stern), the waterline does not become too full and the resistance to movement does not increase very much. Above the load waterline, the frames at the ends of the vessel are usually cambered in order to obtain the maximum reserve of buoyancy to reduce the keel net, reflect the waves flooding the deck and increase the deck area at the ends of the vessel.

Cruising stern: a- single-rotor vessel, b- twin screw vessel

The shape of the fore and sternposts largely determines general form ship. However, the shapes of the ends are chosen not only from an aesthetic point of view, but also from the point of view of the resistance of the vessel (bulb bow). The purpose of the ship also plays a role; for icebreakers, for example, special icebreaking stems have been created that allow the vessel to rest on the ice surface with the entire weight of the bow and break it. To do this, the stem waterline break should be convex, and the entry angle should not be too large. so that the ice floes can move back unhindered. The fillets of propeller shafts in twin-screw ships are shaped so that the oncoming flow hits the propeller against the direction of its rotation. Therefore, they are not installed vertically to the frames, but, starting at an angle of 90 °, towards the end they descend to the horizontal at an angle of approximately 25 °. Based on practical experience and model tests, several types of contour shapes have been created that meet the requirements in terms of load capacity, speed, stability and seaworthiness. For ships of large sizes and serial construction, model tests are usually carried out to match the power of the engine with speed.

4.4.5 Shipping units

In connection with the important role of the English-speaking countries in shipbuilding and shipping that has survived to this day, in practice and in specialized literature, along with the international system of units, the Anglo-Saxon basic units are also used.

Simultaneously with the nautical mile in shipping, when determining the location of a vessel at sea and for measuring speed, a nautical mile is used: 1 nautical mile = 1/60 of a meridian degree = 1852.01 m.

This unit will be obtained if we take two straight lines coming out of the center of the Earth with an opening angle of 1 minute = 1/60 degrees, and measure the distance between them along the perimeter of the Earth (great circle). Since the circumference contains 360 degrees = 21600 minutes, then, therefore, a nautical mile is equal to 1/21600 of the circumference of the Earth, which is approximately 40,000 km. From the unit of length 1 NM, by correlating it with the unit of time 1 h, the speed in knots (knots) is derived: 1 knot=1 NM/h = 1.852 km/h.

From these units of length, units of area and volume are derived. 1 register ton is the basic unit and is used to measure the tonnage of a ship.

A significant role in determining the amount of cargo is played by units of mass; in international trade, in addition to the generally accepted ones, the following English units of mass are also used:

1 long ton = 20 long quintals = 80 long quarters = 160 ston = 2240 pounds = 1016.047038 kg

1 lb (lb) - 0.454 kg

1 ston = 6.350 kg

1 long quarter = 12.701 kg

1 long hundredweight = 50.802 kg

Along with English units of mass, American units are used, which coincide with English ones. However, when concluding charter contracts, there are:

Metric ton (t) \u003d 1000 kg - for sea transportation between German, Scandinavian, Dutch, Belgian, French and other ports, i.e. between countries in which the metric system is adopted;

English ton - long ton (long ton) = 1016 kg - for sea transport from the UK and to the UK (however, metric tons are also used);

North American ton - short ton (short ton) = 907 kg - if we are talking about the North American region.

Gross tonnage (deadweight) is obtained from the gross displacement of the vessel minus the mass of the empty, ready for operation vessel. The carrying capacity of a ship is thus expressed by the mass of cargo that an empty ship ready for operation up to the summer load line can take on board. The payload of the vessel is obtained by subtracting from the gross carrying capacity (deadweight) of the masses of such components as:

Crew and passengers with belongings or baggage;

Stocks of fuel and lubricants;

Provisions and fresh water (water for feeding boilers, washing and drinking water);

Boatswain stores, engine stores and packing materials.

Thus, the payload is a quantity that depends on the mass of production materials (fuel and water), i.e., on the cruising range of the ship. For cargo ships, the payload is approximately 90% of the carrying capacity (deadweight).

The cargo capacity of a ship is the volume of all holds in cubic meters, cubic feet, or in 40 cubic foot "barrels". Speaking about the capacity of holds, the capacity is distinguished by piece (bales) and bulk (grain) cargo. This difference follows from the fact that in one hold, due to floors, frames, stiffeners, bulkheads, etc., bulk cargo can be placed more than piece cargo. The general cargo hold is approximately 92% of the bulk cargo hold. The calculation of the ship's capacity is made by the shipyard; capacity is indicated on the capacity chart, and it has nothing to do with the official measurement of the vessel, which will be discussed in the next section.

Specific cargo capacity is the ratio of the capacity of the holds to the mass of the payload. Since the mass of the payload is determined by the mass of the necessary operational materials, the specific cargo capacity is subject to slight fluctuations. General cargo ships have a specific cargo capacity of about 1.6 to 1.7 m 3 /t (or 58 to 61 cubic feet).

4.4.6 Measurement of ships

To determine the size, the vessel is measured. In 1854, after the introduction of the D. Moorsom measurement method in England, the size of the vessel began to be determined using a measure of internal space. Measure in 100 cu. feet is called a "ton" (barrel); hence, since the results of the measurement are entered into the ship's register, a registered ton arose: 1 reg. t = 100 cu. ft = 2.83 m3.

The ton as a measure of volume has been used since the days of the Hansa trade union, when the size of a vessel (cargo capacity) was determined by the number of barrels that could fit into the holds. Carrying capacity or displacement was not at that time considered a suitable measure for determining the size of a ship.

The Mursom measurement method (sometimes with significant deviations) has since been the basis for drawing up the Measurement Rules for many states and joint-stock companies operating channels through which maritime transportation is carried out, as well as in the preparation of international Rules for the measurement of ships.

Vessel measurement is an administrative act carried out by special government bodies and is formalized by drawing up official document- a tonnage certificate, which indicates the gross tonnage (gross), net tonnage (net) and dimensions of the ship's identity.

The measurement results serve commercial and statistical purposes. In accordance with them, laws are established on the payment of port and pilotage dues, dues for the passage of canals and on the payment of other taxes, crews are recruited for ships and statistical records are made of the gross registered tonnage of the merchant fleet of the corresponding country. In addition, measurement data is important for the technical equipment of the ship with emergency equipment, steering and other devices, fire fighting equipment, telegraph, radio and direction-finding installations, etc. The gross register tonnage of the fleets of individual countries is taken into account when determining the composition of participants international conferences adopting various conventions, etc.

In a number of countries, international rules measurements sea ​​vessels in accordance with the Agreement on a unified system for measuring ships, concluded on June 10, 1947 in Oslo. As a result of this measurement, an international measurement certificate is drawn up, which is recognized by all countries - parties to the agreement without additional verification. Along with the international measurement certificate, there are also national measurement certificates and measurement certificates for passage through the Suez and Panama Canals. By international system measurements determine the gross tonnage and, by certain deductions, the net tonnage.

Gross tonnage(BRT) is the total capacity of all watertight enclosed spaces; thus, it indicates the total internal volume of the vessel, which includes the following components:

The volume of rooms under the measuring deck (the volume of the hold below deck);

The volume of rooms between the measuring and upper decks;

The volume of enclosed spaces located on the upper deck and above it (superstructures);

Amount of space between hatch coamings.
The measurement deck on ships with no more than two decks is considered to be the uppermost deck, and on ships with three or more decks, the second from the bottom.
The following enclosed spaces are not included in gross tonnage if they are intended and fit for and used solely for the named purposes:

Premises in which there are power and electric power plants, as well as air intake systems;

Auxiliary machinery spaces that do not serve the main engines (e.g. refrigeration plant rooms, distribution substations, elevators, steering gears, pumps, processing machines on fishing vessels, chain boxes, etc.);

Premises for the protection of people at the helm;

galley and bakery premises;

Skylights, light shafts and shafts that bring light and air to the spaces below them;

Gangways and vestibules that protect ladders, ladder corridors or ladders leading to the premises below;

Bathrooms for crew and passengers;

Ballast water tanks.

To limit the gross tonnage of double and multi-deck ships, all so-called open spaces are not included in the gross tonnage. This may include the spaces between the upper deck and the shelter deck (“shelter deck space”) and other superstructures if they are made open by gauge hatches in the upper deck or gauge holes in bulkheads. In order to be able to exclude spaces below the upper continuous deck from measurement, it is necessary to create a so-called measurement space by means of a measurement hatch, from which adjacent compartments can be made open with the help of measurement holes. As closures for measurement hatches, only loosely laid wooden bars, it is allowed to use U-shaped metal strips or sheets held by L-bolts as cover for measuring holes in bulkheads.

A ship that has openings in the upper deck without strong watertight closures (gauge hatches and openings) is called a sheltered ship or a ship with a hinged deck; it has a smaller register capacity because of such holes. Closed interior volumes in open spaces that have strong watertight closures are included in the measurement. The condition for exclusion from the measurement of open spaces is that they do not serve to accommodate or serve crew and passengers. If the upper deck of double-deck or multi-deck ships and bulkheads of superstructures are fitted with strong watertight closures, the space between decks below the upper deck and superstructure spaces are included in the gross tonnage. Such vessels are called full-set and have a maximum allowable draft.

net tonnage(NRT) is the useful volume for accommodating passengers and cargo, i.e. commercial volume. It is formed by subtracting the following components from the gross tonnage:

Premises for the crew and navigators;

navigation facilities;

Premises for skipper stores;

Ballast water tanks;

Engine room (power plant premises).

Deductions from gross tonnage are made according to certain rules, in absolute values or as a percentage. The condition for the deduction is that all these spaces are included in gross tonnage first.

In order to be able to check whether the tonnage certificate is genuine and belongs to this vessel, it indicates the dimensions of the identity (identification dimensions) of the vessel, which are easy to verify.

Estimated length (identical) is the length along the uppermost continuous deck from the trailing edge of the stem to the middle of the stock, and for ships with a mounted rudder

To the trailing edge of the sternpost.

Design width (identity width) - the width of the ship at its widest point. Design draft (identity draft) - the distance between the lower edge of the uppermost continuous deck and the upper edge of the second bottom plating or floors at the middle of the draft length.

Economic considerations led to the creation of a shelter deck ship, since "open" spaces, as mentioned above, are not included in the gross tonnage. But since the closure of the measuring holes of the shelter deck or other “open” spaces prescribed by the rules reduces the reliability of ships, such volumes, according to the Rules on the Load Line, should not be taken into account when calculating the freeboard - the ship's buoyancy. Before the introduction of international unified system measurement of ships in the Measurement Rules, currently in force on the recommendation of the Intergovernmental Maritime Consultative Organization (IMCO) of October 18, 1963, by introducing a tonnage mark, the advantage of open spaces should be maintained, despite the watertight closures of shelter decks and other spaces. The principle underlying the recommendations for the introduction of a tonnage mark is that certain tween-deck spaces, which are considered open and therefore not included in the gross tonnage, may be closed for a time, and such spaces are considered separate if the tonnage mark , located below the second deck on the sides of the vessel, when the vessel is loaded, lies not below the waterline. Spaces suitable for allocation and located in free-standing superstructures or deckhouses on or above the upper solid deck should, in spite of strong watertight closings, be excluded from the gross tonnage, whether or not the tonnage mark is loaded.

Load lines: 1 - tonnage line, 2 - load line

The tonnage (measuring) mark is applied on each side of the vessel aft of the freeboard mark. In no case should the tonnage mark be applied above the load line - the freeboard mark. An additional line for fresh water in tropical waters is given, as a rule, minus 1/48 of the draft above the upper edge of the keel to the measurement mark. In the event that the tonnage mark (upper edge of the horizontal line) is not loaded, the gross and net tonnage of the spaces located inside the upper tween deck and suitable for allocation are used for commercial purposes.

Hull

The ship's hull is a box-shaped beam with thin walls and reinforcements, which at the ends at a more or less acute angle passes into the fore and stern. The side skin and all continuous longitudinal bulkheads form the walls of this box-shaped beam.

The bottom decking (including the bilge belt), the decking of the second bottom and all longitudinal bracings passing through the double or single bottom form the lower girdle of the box girder "vessel", and the solid deck deck next to the hatches and the continuous longitudinal bracing of the main deck, as well as the sheerstrake ( the uppermost belt of side plating sheets) - upper. The upper and lower belts perceive normal tensile and compressive stresses from the buckling of the ship.

Internal reinforcements are beams located parallel and perpendicular to the diametrical plane of the vessel (longitudinal and transverse sets). They serve to absorb and transmit local loads (hydrostatic and hydrodynamic pressures, cargo pressure) and to stiffen the upper and lower flanges, and also protect the outer skin from deformation.

In height, the ship's hull is divided into decks. The sides, bottom and decks of the vessel converge at the extremities and end with fore and sternposts. Watertight bulkheads divide the hull into watertight compartments and reinforce it as a transverse set. On the uppermost continuous deck - the main deck - there are superstructures and deckhouses. Long superstructures in the middle part are included in the upper corbel of the ship's hull.

Longitudinal, transverse and torsional loads on the hull are absorbed due to the appropriate location and execution of the ship's floors. Ceilings of steel vessels consist of sheets and profiles.

Usually, the ship's hull is distinguished by bottom, side and deck ceilings, stems and bulkheads. In addition, there are structural connections of superstructures, deckhouses and other parts of the ship's hull, such as foundations, a propeller shaft tunnel, hatches, shafts.

Structural elements and hull connections: a - afterpeak bulkhead, b - box beam, c - superstructure, d - bow end, e - aft end, f - cargo hatch area, g - area between cargo hatches, h - engine room area, i - main deck in the area of ​​the corner of the cargo hatch 1 - deck of the after peak tank; 2 - stern tube; 3 - the upper belt of the skin; 4 - wall; 5 - lower cladding belt; 6 - deck flooring; 7 - longitudinal hatch coaming; 8 - hatch transverse coaming; 9 - sheerstrake; 11 - zygomatic belt; 12 - flooring of the second bottom; 13 - bottom lining; 14 - chain box; 15 - tween deck; 16 - ram bulkhead; 17 - yut; 18 - emergency exit; 19 - afterpeak; 20 - propeller shaft; 21 - stern tube; 22 - sternpost; 23 - rudder feather; 24 - rudder stock; 25 - tank; 26 - forepeak; 27 - side stringer; 28 - twin deck frame; 29 - hold frame; 30 - upper (main) deck; 31 - propeller shaft tunnel; 32 - carlings; 33 - bottom stringers; 34 - vertical keel; 35 - machine shaft; 36 - upper skylight; 37 - navigation bridge; 38 - boat deck; 39 - deck of the middle superstructure; 40 - upper (main) deck; 41 - foundation of the main engine; 42 - superstructure frame; 43 - extreme double-bottom sheet; 44 - frame beam; 45 - frame frame; 46 - rhomboid slip sheet; 47 - pillers; 48 - nasal breshtuki; 49 - longitudinal rib.

window.google_render_ad();

5.1.1 Structural elements of the ship's bottom

At the bottom floors, two fundamentally different options are distinguished, namely, a single and a double bottom.

As a rule, small vessels with a length of less than 60 m have a single bottom, and above all, vessels with a strong bilge lift and a bar keel. Floors with frames into which they pass form a continuous transverse set. Longitudinal connections in the area of ​​the bottom, the so-called keelsons, protect floras from longitudinal bending. The most important longitudinal connection of a single bottom is the middle keelson, which, along with the reinforcement of the floors and the strengthening of the keel (which is important when docking), increases the longitudinal strength of the vessel.

There are three options for the execution of the middle kilson:

The average kilson standing on floors - for ships shorter than 30 m

Intercostal keelson

Middle keelson in the form of a middle keel leaf

In small vessels, the flora in the diametrical plane is usually not cut. For longer vessels, a continuous bottom keel is preferred for better longitudinal load absorption. Depending on the width of the vessel, one or two bottom stringers are installed on each side, the purpose of which is the same as that of the middle keelson. The distance between the bottom stringers and the middle keelson and their distance from the ship's sides is not more than 2.25 m; in the fore end, due to the heavy load on the bottom during pitching, they are installed at a smaller distance from each other. The floors consist of sheets supported by vertical stiffening ribs, running across the entire width of the vessel and interrupted only by a continuous middle keelson. At the ends of the vessel, in the fore and after peak, floors are made higher, in the after peak they reach a level above the stern tube. A single bottom between the ram and after peak bulkheads (with the exception of the engine room) is covered with a wooden deck. In the area of ​​​​the engine room, a simple bottom is covered with bottom sheets (spruces), usually from corrugated sheets.

With a double bottom, there is a second waterproof bottom above the longitudinal and transverse braces located on the bottom chords of the outer skin. The double bottom design resembles a flat box beam. The cross-links at the double bottom also consist of floors. A double bottom has the following advantages over a single bottom.

1. Increases the strength of the vessel during grounding; in case of a leak in the double bottom area, buoyancy is preserved, since water can only penetrate to the second bottom flooring. For this reason, the requirements international convention for protection human life At sea, small passenger ships are required to have a second bottom in the bow from the engine room bulkhead to the collision bulkhead, and large passenger ships (over 76 m in length) - from the afterpeak to the collision bulkhead.

2. By watertight longitudinal and transverse bracing, the double bottom is divided into tanks to accommodate liquid fuel, fuel oil and lubricating oil, wash, feed and ballast water.

On the other hand, a double bottom increases the dead weight of the vessel and increases the construction cost. Therefore, on small ships, it is abandoned or installed only in the engine room area for fuel and lubricating oil tanks. The vertical keel serves not only to increase the longitudinal strength of the vessel and as the main support during docking, but also to increase the rigidity of the bottom between the two bulkheads, as well as to prevent deformation of the floors. The keel runs from stern to bow through the entire vessel. In the middle of the length of the vessel, it is made watertight in order to divide the double bottom in width and reduce the free surface in the double bottom tanks. At the extremities, where, due to the small width of the vessel, the tanks pass from side to side, the vertical keel is equipped with lightening cutouts (manholes). Depending on the width of the vessel, one, two or more intercostal bottom stringers are located on either side of the vertical keel, which perform the same tasks as the vertical keel.

In order to reduce the weight of the vessel and make the double bottom accessible, cutouts are provided in the bottom stringers, if they do not serve to water-tightly separate the vessel from oil. The flooring of the second bottom, together with the extreme double-bottom sheets, forms the bottom floor. The extreme double-bottom sheet is either inclined to the flooring of the second bottom and approximately at a right angle to the cheekbone, or lies in the plane of the second bottom. For access to the double bottom, at the end of each of its compartments, a closing hatch is made in the flooring. The transition from floors to side frames at the extreme double-bottom sheets is carried out with the help of zygomatic knees, and at the horizontal extreme double-bottom sheets - with the help of knees.

Floors are located in a double bottom at a right angle to the center plane of the ship. As a rule, they run from the vertical keel to the outer bottom plate. In this case, three types of floras should be distinguished. Watertight floors form the boundary of double bottom tanks and can be compared in function to watertight transverse bulkheads. With a high double bottom height (more than 0.9 m), they are supported by vertical stiffeners. Solid floras are similar to waterproof ones. Since they are not intended to be either watertight or oiltight, cutouts are made in them to reduce their own weight and allow access to the individual compartments of the double bottom. Continuous floors, depending on the length of the vessel, are placed in the bow at every third or fourth frame; on ships for transportation heavy cargo, under the engine rooms, as well as under the transverse bulkheads, heavy and end pillars of the middle diametral bulkheads - on each frame. Open bracket floors are placed on frames that do not need waterproof or solid floors. They consist of rolled profiles, which are installed on the bottom plating (lower corner of the floor) and on the decking of the second bottom (upper corner of the floor). Brackets are used to connect floors with a vertical keel, bottom stringers and an extreme double-bottom sheet.

Double bottom: a - separation of the double bottom; b - double bottom with solid and bracket floors; c - double bottom with a longitudinal set (with longitudinal stiffening ribs); d - double bottom with bottom stringers. 1 - ballast water (forepeak); 2 - ballast water (double bottom); 3 - fuel; 4 - lubricating oil; 5 - cofferdam; 6 - fresh water; 7 - shelf of the zygomatic knitsa; 8 - flooring of the second bottom; 9 - waterproof floor; 10 - open bracket floor; 11 - upper square flora; 12 - bottom square flora; 13 - brackets; 14 - solid floor; 15 - horizontal keel; 16 - vertical keel; 17 - side stringer; 18 - cheekbone stringer; 19 - zygomatic knee; 20 - hold frames; 21 - zygomatic knee; 22 - bottom longitudinal beams; 23 - longitudinal beams of the second bottom; 24 - extreme double-bottom sheet; 25 - bottom stringers.

Currently, instead of permeable floors, usually solid floors with enlarged cutouts are installed. The manufacture and assembly of solid floors is simpler than bracket ones, however, when in contact with the ground, solid floors reduce deformations of the bottom structures; in addition, solid floras are only slightly heavier than bracketed ones. Cheek brackets, or knees, connect the hold frames with the extreme double-bottom sheet or the second bottom, i.e. with the bottom transverse braces, and reinforce the cheekbone. To reduce weight and for laying pipelines, cheekbones are provided with cutouts. The free edge of the zygomatic brackets is bent or provided with a belt or a horizontal knee. Horizontal brackets serve to reinforce the transverse framing interrupted by the outer bottom plate and to create an effective transition from the bilge bracket to the second bottom deck and thus to the bottom floors or bracket.

Along with the traditional method of building a second bottom with bracket or solid floors on each frame, in recent decades, the method of building with longitudinal stiffeners has been increasingly used, and for large ships (more than 140 m long) - with bottom stringers. The advantage of the longitudinal framing system is that it significantly increases the longitudinal strength of the bottom. The bottom longitudinal stiffeners or stringers, together with the skin, perceive the bending stresses of the ship's hull (tension and compression) that occur in the bottom, as well as local loads. A double bottom with longitudinal stiffening ribs or stringers with the same strength is lighter than a double bottom with floors on each frame. The disadvantage is that the process of manufacturing ships in this way is more laborious (especially when bending stiffeners for the ends) and, therefore, more expensive.

With a longitudinal framing system, solid floors are placed on every third or fourth frame, i.e., at a distance of approximately 3.6 m from one another; only in the area of ​​the bow of the ship and under the foundations of the main engines these distances are less. The distances of the bottom stringers from each other or from the vertical keel and the outermost double-bottom sheet are approximately 4.5 m; in the area of ​​the bow and under the engine room, they are smaller. Brackets are placed between the floors at the extreme double-bottom sheet, and at the bottom stringers - vertical stiffeners at a spacing distance; at the vertical keel, depending on the distance between floors, one or two brackets with flanges are additionally placed on both sides. The bottom stiffeners, which, depending on the size of the vessel, are installed at a distance of 0.7-1 m, pass through solid floors. With a longitudinal framing system with stringers, elliptical or arched cutouts are made in the latter.

5.1.2 Shell and side framing

Sheathing is the shell of the ship's hull; it must perceive water pressure and at the same time, as part of the longitudinal set, together with other longitudinal connections, provide the longitudinal strength of the ship's hull. The outer skin consists of separate sheets, which are connected to each other by means of welding, with frames, decks and bottom connections. The length of the outer skin sheets is usually much greater than the width. Vertical connection line ( weld) of sheets is called a joint, and a more or less horizontal connection line is called a groove. The grooves form harmoniously flowing curves along the length of the vessel. The sheathing belts passing between these so-called curved curves are called belts. Each belt has its own name in accordance with its position on the ship's hull. Belts of sheets that adjoin directly to the keel are called keel, the remaining belts, as well as belts next to the horizontal keel in the flat part of the bottom, are called bottom. The belt of sheets, which covers the rounding of the cheekbone, is called the zygomatic belt, the belts of the sheets in the flora above the zygomatic belt are the side belts, the uppermost one is the sheerstrake. The number of joints and seams depends on the size of the sheets. Depending on the size of the ship, the width of the sheets is from 1.2 to 2.8 m, and the length is from 5 to 10 m. Smaller sheets are installed at the ends of the ship, since volume bending and installation of large sheets would be too laborious. The thickness of the outer skin depends on the length of the ship, the height of the side to the upper continuous deck, as well as on the draft and the distance between the frames (spacing). This thickness is about 5 mm for ships 20 m long and about 25 mm for ships 250 m long. But even for the same ship, the thickness of the outer skin is not the same everywhere. So, during waves, the ship experiences the largest bending stresses in the middle part, so the sheets are thicker there than at the ends. As a rule, sheerstrake and horizontal keel are also thicker than other sheet chords, because they are important longitudinal braces and are additionally subject to loads acting on transverse braces. Large compressive loads are experienced by the horizontal keel during docking, so the bottom chords are thicker than the side ones.

Outer skin:
1 - sheerstrake, 2 - bulwark, 3 - leaf stem, 4 - seam, 5 - leaf belt, 6 - leaf joints, 7 - zygomatic belt, 8 - side belt, 9 - bottom belts, 10 - horizontal keel, 11 - area reinforcements, 12 - superstructure side skin

window.google_render_ad();

The belts of the outer plating sheets in the area of ​​transition to the superstructure were also strengthened, since a particularly high concentration of stresses occurs there when the ship bends in waves. Due to pitching, in addition to the bottom set, the outer skin is also reinforced in the bow and stern ends. Vessels with ice reinforcements have thicker side plating, especially if they are built in accordance with the Rules for a higher ice class and for operation in Arctic waters. Not only the outer skin has ice reinforcements, but also side connections - frames and stringers, as well as fore and sternpost, steering gear and separate parts of the power plant, such as a propeller, shaft line and engine crankshaft.

Frames - the ribs of the ship's hull, which are located in vertical planes and give the ship its shape. They are a continuation of the transverse links of the bottom of the vessel and form with bottom floors, bilge knees or brackets, beams and beams a frame frame, open in the hatch area and closed outside the hatches and shafts. The frames, together with other transverse braces, must provide local strength to the hull so that the ship can absorb the loads acting on it from the pressure of water, ice and cargo. In connection with the transverse bulkheads, the frames also increase the longitudinal strength of the vessel, preventing deformation of the outer skin. The frames are distributed along the entire length of the vessel (with the exception of the extremities) at equal distances from each other. This distance, depending on the length of the vessel, is from 0.5 to 0.9 m. As a rule, the frames are numbered from the bow perpendicular to the stern, starting from "0"; frames behind the aft perpendicular receive negative numbers. The load on the frames increases downward from the water surface in accordance with the increase in hydrostatic pressure. Therefore, their cross sections are maximum in the area between the bottom and the lowest deck; from deck to deck, they gradually decrease. The dimensions of the hold frames depend on the size of the vessel, on the draft and on the height of the bilge brackets. The usual end fastenings of hold frames to beams are shown in the figure. In ships with a single bottom or with a horizontal decking of the second bottom, the hold frames at the outer plating are connected to the floors in a nakra so that the connection is sufficiently rigid in bending; sometimes they are attached with the help of knits. The dimensions of the tweendeck frames also depend on the size of the vessel, i.e., on the height of the side to the main deck, on the height of the tween deck, the number and position of the tween deck, on draft and spacing. The usual end fastenings of intermediate frames to decks and beams are shown in the figure. The dimensions of superstructure frames and their end fastenings are determined in the same way as for tween deck frames.

Frames and side set:
a - the location of the frames (side view); b - connection of the ship's side with a single bottom; With - onboard set of a single-deck vessel in the cargo hatch area; d - onboard set of a three-deck vessel; e - on-board set in the engine room area; f - a set of cruising stern.
1 - twin deck frames; 2 - knees; 3 - hold frames; 4 - shelf of the zygomatic knitsa; 5 - cheekbone; 6 - beams; 7 - transom sheet; 8 - stern frames; 9 - sternpost; 10 - longitudinal coaming; M - transverse coaming; 12 - frame beam; 13 - frame frame; 14 - side stringer; 15 - intermediate deck; 16 - bottom floras; 17 - middle kilson; 18 - connection of the frame with the floor.

window.google_render_ad();

In those areas of the ship's hull where particularly high stresses occur or where the ship's hull must be especially rigid (for example, in the engine room area), reinforced frame profiles are installed in the area of ​​​​large hatches - the so-called frame frames. They consist of walls with welded shelves. At the ends of large cargo hatches, frame frames, together with hatch end beams and hatch transverse coaming, form a closed frame of great rigidity and strength.

In the stern (with a cruising stern), the frames are located in planes that are not vertical to the diametral plane, since otherwise the walls of the frames would be too inclined to the outer skin and would significantly reduce its strength. Therefore, the stern frames are located in planes that are located at different angles to the diametrical plane and almost vertically to the outer skin. Together with appropriately positioned beams, they form separate frames, which are attached to the so-called transom sheet. The transom sheet is a sheet equipped with reinforcements and located at right angles to the longitudinal axis of the vessel. It connects to the sternpost and replaces the floor in this place.

To reinforce the frames, side stringers are installed in the bow and stern ends. The fore peak and after peak under the lowest deck are additionally reinforced with frame stringers. If the fore peak and after peak are conceived as tanks, then additional stringers are installed between the frame stringers at half the distance. Vessels with ice reinforcements are provided with additional frames; for ships with smaller ice reinforcements, they are limited to the bow; vessels of a higher ice class have additional frames and stringers along the entire length of the vessel. In the area of ​​ice reinforcements, the outer skin can withstand ice pressure up to 784.8 kPa.

Onboard bow set:
1 - main deck, 2 - side stringer, 3 - stem, 4 - reinforced side stringer, 5 - floors, 6 - beams, 7 - ram bulkhead, 8 - double bottom, 9 - hold frames, 10 - bow bulkhead

Decks and below deck set

Decks are floors in the ship's hull that run almost horizontally. The uppermost continuous deck - the main deck - closes the hull from above and forms, alone or with a long superstructure deck, the upper hull shell. Decks below the main one have the task of increasing the usable area of ​​the vessel for accommodating passengers and cargo. Decks above the main deck are called superstructure decks.

The vertical distance between the decks on which the crew and passengers are accommodated is from 2.2 to 2.8 m. The height between the cargo decks is from 2.5 to 3.5 m, and the height of the cargo spaces lying under the lowest deck is 6 m and more. The thickness of the main deck plating depends on the length of the ship, the depth of the side to the main deck, the height of the tween deck, the draft, the framing system (longitudinal or transverse) and the distance between the beams, as well as the width of the continuous deck between the cargo hatches and the shell plating. At the same time, the thickness of the deck flooring varies depending on the magnitude of local loads acting on the ship's hull: they are the largest in the middle part of the ship, and become smaller towards the ends. In addition, deck plating between hatches is usually significantly thinner than deck plating between hatches and shell plating. The thickness of the main deck sheets ranges from 5 to 30 mm, depending on the length of the vessel. The corners of the hatches are sheathed with reinforced or doubled sheets to avoid rupture of the deck flooring due to stress concentration.

The flooring of the lower decks has a slightly smaller thickness, which depends on the load and on the distance between the beams and is about 5 mm for small ships, and rarely exceeds 12 mm for large ships. The deck flooring, like the outer skin, is made from separate belts of sheets, and the belts lying at the sheerstrake are called deck stringers, and the belts running along the hatches are called hatch stringers.

Before the deck stringers, all sheet chords run parallel to the diametral plane. Deck stringers taper at the ends of the vessel and end with sheets located across the vessel. In the amidships of the vessel, the deck stringers of the main deck are sometimes riveted with the help of a stringer square to the outer skin of the vessel (with sheerstrake).

Beams passing across the vessel with a longitudinal framing system carry the deck flooring and the cargo lying on the deck. They are reinforced with longitudinal deck beams and pillars in one or more places along the width of the vessel. Longitudinal underdeck beams pass through the frame beams and rest on them. The dimensions of the beams depend on the load on the deck, the span length and the distance between the beams; in addition, the beams of the main deck amidships must have a minimum stiffness (moment of inertia), which depends on the thickness of the main deck, in order to protect the deck plating from deformation under compressive stresses. The deck beams are connected to the frames with the help of knees. Beams interrupted by access hatches or other cutouts are supported by carlings (longitudinal beams) that are attached to reinforced deck beams.

Longitudinal deck beams consist of welded profiles. In places where the beams pass, they are provided with cutouts in accordance with the profile of the beam. T-profiles are protected from deformations and displacements by brackets. The longitudinal deck beams are usually attached to the transverse bulkheads with the help of knees. The dimensions of the stringers depend on the load on the deck and on the span and width of the floor that bears the load. Pillers run from the floors or second bottom deck to the uppermost deck; on separate decks, they stand exactly on top of each other, otherwise the beams would receive additional bending load. Pillers are made from steel pipes (rarely from squares) or other rolled products. At the ends they have heel plates and top linings, and on both sides of the wall of the longitudinal beam - vertical brackets, which serve to reliably transfer the pressure of the deck and beams to the pillars and prevent lateral displacement of the longitudinal beam. The cross sections of the pillars are determined by the load and length.

window.google_render_ad();

Decks: a - names of decks; b - deck with a transverse framing system; With - deck with a longitudinal framing system.

1 - poop deck; 2 - main deck (bulkhead deck and freeboard deck); 3 - second deck; 4 - propeller shaft tunnel; 5 - navigation bridge; 6 - command bridge; 7 - boat deck; 8 - deck of the middle superstructure; 9 - bottom lining; 10 - tank deck; 11 - third deck; 12 - flooring of the second bottom; 13 - seams; 14 - cargo hatches; 15 - joint; 16 - hatch reinforcements; 17 - machine shaft; 18 - deck stringer; 19 - beams; 20 - carlings; 21 - diamond-shaped sheet; 22 - frame beams; 23 - hatch stringers; 24 - deck flooring (next to the side and hatches are deck and hatch stringers); 25 - flooring between hatches; 26 - longitudinal deck beams; 27 - frame beam; 28 - corrugated bulkhead.

Bulkheads and tanks

A bulkhead is a water- and dust-tight vertical wall installed in the ship's hull. According to the position relative to the DP of the vessel, longitudinal and transverse bulkheads are distinguished. Watertight bulkheads divide the ship into watertight compartments; for passenger ships, they are located so that when one or more adjacent compartments are flooded, the ship's buoyancy is preserved. Transverse bulkheads increase the transverse strength and, preventing buckling of the sides and ceilings, the longitudinal strength of the vessel. Watertight and oiltight longitudinal bulkheads are installed only on ore carriers and tankers.

The number of watertight bulkheads depends on the length and type of vessel. An emergency collision bulkhead is provided on each ship behind the stem. For screw ships, an afterpeak bulkhead is installed at the aft end, which usually limits the afterpeak. Steamboats and motor ships have one transverse bulkhead at the ends of the engine and boiler rooms. The rest of the hull is divided according to the length of the vessel by other transverse bulkheads, the distance between which does not exceed 30 m. The collision bulkhead in ships with a solid superstructure or forecastle extends from the bottom to the deck of the superstructure or forecastle, while the afterpeak bulkhead usually reaches only to the watertight deck above the summer load waterline.

Watertight transverse bulkheads:
a - location of bulkheads at the cargo ship (full-board ship); b - transverse bulkhead; With - corrugated bulkhead; d - ram bulkhead.
1 - yut; 2 - afterpeak; 3 - after peak bulkhead; 4 - holds; 5 - middle superstructure; 6 - bulkhead deck; 7 - engine room; 8 - lower deck; 9 - tank; 10 - chain box; 11 - forepeak; 12 - ram bulkhead; 13 - double bottom; 14 - propeller shaft tunnel; 15 - knees; 16 - bulkhead sheathing belts.

window.google_render_ad(

§ 6. Relationships of the main dimensions and coefficients characterizing the shape of the ship's hull

In addition to the previously mentioned general information about the shape of the contours of the diametrical plane, the constructive waterline and the midship frame, for a more complete characterization of the shape of ship hulls and an idea of ​​the seaworthiness and operational qualities of ships that depend on it, it is necessary to know the following numerical ratios of the main dimensions of the vessel:

1) the ratio L / B, affecting the propulsion of the vessel;

2) V/D ratio, which affects the ship's stability, propulsion and rolling. An increase in the relative width improves the stability of the vessel, but the roll becomes sharper and the resistance of the water to the movement of the vessel increases;

3) the H/T ratio, which affects the ship's unsinkability. An increase in the relative height of the side improves the unsinkability of the vessel;

4) the ratio L / T, affecting the agility of the vessel. An increase in the relative length of the vessel worsens its agility;

5) the L/H ratio associated with the characteristic of the overall longitudinal strength of the ship (according to the USSR Register Rules, L/H should be in the range from 9 to 14).

Finally, the form of the underwater part of the ship's hull can be judged by dimensionless coefficients of completeness obtained by comparing the main areas and volumes of the hull with the corresponding areas and volumes of the simplest geometric shapes and bodies built on its main dimensions.

Such basic coefficients of completeness of the underwater part of the ship's hull are:

A) the coefficient of completeness of the constructive (cargo) waterline a - the ratio of the area of ​​the waterline 5 to the area of ​​the circumscribed rectangle, built according to the estimated length L and the width of the hull B (Fig. 8, a)

b) coefficient of completeness of the midship frame c - the ratio of the area of ​​the submerged part of the midship frame w to the area of ​​the circumscribed rectangle built according to the estimated width B and draft of the hull T (Fig. 8, b)

Rice. 8. Coefficients of completeness of the underwater part of the ship's hull: a - waterline; b - midship frame; c - displacement.

c) coefficient of completeness of displacement B - the ratio of the volume of the underwater part of the hull V to the volume of the described parallelepiped, built on the estimated length L, width B and draft of the hull T (Fig. 8, c)

In addition to the three given main and independent coefficients a B and b, two coefficients φ and y) are used, which are derivatives of the first and the following relations associated with them:

D) coefficient of longitudinal completeness f - the ratio of the volume of the underwater part of the vessel V to the volume of a prism with a base equal to the area of ​​the submerged part of the midship twine w, and a height equal to the length of the hull L,

Substituting their values ​​instead of o and V, after simplification, we obtain the dependence of this coefficient of overall completeness and the completeness of the midship frame

The coefficient f expresses the distribution along the length of the hull of the volume of its immersed part, which affects the resistance of water to the movement of the vessel;

E) coefficient of vertical completeness y - the ratio of the volume of the underwater part of the hull V to the volume of the prism, the base of which is equal to the area of ​​​​the design (load) waterline of the ship S, and the height is the draft of the hull T

The coefficients of completeness of waterlines can be calculated by the approximate formula:

Accept

Fullness ratio midship - frame:

Accept

4.8 Determination of the maximum load capacity

The specific load capacity µ can be determined from the load capacity equation, provided that the relation is maintained
, where - specific loading cubic capacity.

, where
- coefficient taking into account passages, ladders, other places not occupied by cargo;

- coefficient of completeness of the hold;

- coefficient taking into account the volume occupied by the set, double bottom and double sides in the area of ​​the hold;

- the ratio of the length of the holds to the length of the vessel.

Then the definition of specific cargo capacity

4.9 Analysis of the results.

Based on approximate calculations, we have the following main characteristics:

5Development of a sketch of the general arrangement. Determining the ship's center of gravity. trimming

Let's start the development of the general layout by dividing the body into compartments. Practical spacing can be selected:

The rules allow deviation from this value within

In the forepeak and afterpeak, the spacing should be no more than 600 mm; therefore, it is advisable to take a spacing of 0.6 m along the entire length of the vessel. The forepeak bulkhead shall be impervious to the freeboard deck and extend not less than 5% of the ship's length and not more than 3+0.05L

, where - forepeak length

Accept = 6.6 m or 11 spacings.

The afterpeak bulkhead shall be impermeable to the freeboard deck and the distance from the bulkhead to the perpendicular shall be chosen taking into account the design of the aft end. This distance takes 11spacing or 7.2m.

We install a transverse bulkhead from the forepeak to the stern, separating the device and the service room. The length of this compartment is 5 spacings or 3 m.

We place the engine room and the living superstructure in the stern, like in the prototype. The rest of the hull is reserved for cargo holds. The length of the engine room is 32 frames or 19.2 m. In the area of ​​\u200b\u200bcargo spaces, the sides are double and we install two transverse bulkheads dividing the cargo space into three holds, each with a length of 30 frames or 30 m. The total number of transverse bulkheads on the ship is 6, which meets the requirements of the Register. The double bottom extends from the forepeak bulkhead to the afterpeak bulkhead.

According to the accepted general arrangement scheme, we draw a sketch in Figure 5.1. Using the sketch of the general position and the load of the masses, we determine the position of the ship's center of gravity along the length and height. The calculation is carried out according to table 5.1.

T table 5.1 - Calculation of the ship's center of gravity

	Name
	Housing equipped
	Mechanisms
	Reserve displacement
	Light displacement
	Crew, provisions, water
	Cargo transported
	Fuel, oil
	Variable liquid cargoes
	Displacement fully loaded

After that, you can proceed to trim the ship in full load, so that the ship in full load sits on an even keel, then its center of gravity should be on the same vertical with the center of magnitude, i.e.
.

The center of magnitude is determined by the approximate formula:

Thus we accept