Cargo ship without ballast

Abstract

The examples refer to a ballastless cargo ship (100) which comprises a hull having an upper body (101) and a lower body (102) located below the upper body (101). The upper (101) and lower (102) bodies have a rectangular cross-section along the length of the hull, the lower body (102) being of smaller dimensions than the upper body (101). The ship further comprises cargo spaces (110) arranged within the upper body (101) and void spaces (109) within the lower body (102).With a predefined parameter selected from a maximum draft, a minimum draft and a maximum waterline width of the vessel, the geometry of the vessel is defined by: a ratio between a width of a flat bottom wall of the vessel and a maximum waterline width at the waterline area of ​​the vessel between 0-0.7, a ratio between a submerged draft of the upper body and a maximum draft of the vessel between 0-0.8, and a cutting coefficient at the master between 0.65-0.85. Figure for abstract: Figure 2.

Description

Title of the invention: Ballastless cargo ship Technical field

[0001] In general, the present invention relates to ships, and more preferably to cargo ships, without a ballast system and having a shape consisting of two distinct bodies, upper and lower. STATE OF THE ART

[0002] A ship, particularly a cargo ship, is designed taking into account the weight of the ship itself and the weight of the cargo that must be carried on board. Therefore, when the ship has no cargo or is partially loaded, it floats higher off the water surface and may become unstable to navigate waves and crosswinds, and may be susceptible to trimming or listing. In addition, the ship's propellers come close to the water surface, which can damage them by cavitation and cause them to operate at a lower RPM than recommended, increasing propeller wear and the need for maintenance. To avoid these problems, ships normally incorporate a ballast system comprising tanks containing seawater that maintains the necessary draft to ensure propeller efficiency, safe navigation and ship balance.Ballast water is normally loaded and unloaded in different ports that may be located in different countries or continents. Due to the improvement in ship speed, ships are able to travel from one country to another in a short time with live aquatic species, especially invasive marine species, contained in the ballast water, so when this ballast water is unloaded in a location far from where it was loaded, the release of these live aquatic species can cause environmental problems by disrupting ecosystems on a global scale.

[0003] In order to prevent certain species from entering the ballast tanks, some ships incorporate filtration systems that block said species. Other ships incorporate ballast water treatment systems that include heating systems, ultraviolet light systems, deoxygenation systems, etc. in order to kill or at least reduce the amount of live aquatic species contained in the ballast water. However, all of these solutions are inefficient and have high installation and maintenance costs. In addition, these solutions require large amounts of energy to operate and therefore require burning more fuel oil, resulting in higher emissions.

[0004] Some vessels, known as "loose ballast vessels", incorporate a group of structural lockers extending the entire length of the vessel. During operations ballast, these trunks can be open to the sea with an intake opening at the bow and a discharge opening at the stern, being subjected to a flow of water from the intake opening to the discharge opening. In this way, these trunks can be flooded, reducing the buoyancy of the hull and allowing the vessel to sink to its desired ballast draft. An example of this type of vessel is disclosed in US2003019413A1 (Parsons). However, this solution is technically complex and adds a large amount of drag to the vessel's hull as it moves through the water.

[0005] Furthermore, multihull vessels without a ballast system are known in the prior art. This type of vessel does not need to carry ballast water. However, the manufacturing and maintenance costs of this type of vessel are significantly higher than those of a monohull vessel. In addition, due to the particular design of these vessels, the integration of a sufficiently large and single-piece hold is difficult, and the waterline width is significantly greater than in monohull vessels. Another disadvantage of these vessels is that when multihull vessels carry heavy loads at low speed, the wetted surface and drag in the seaway increase significantly.

[0006] Vessels having a V-shaped floor plan and provided with a large waterline width are known in the state of the art. In this type of vessel, ballast water may not be necessary to achieve proper control of the vessel's center of gravity under different loading conditions. However, these solutions cannot be applied to the transport of cargoes, e.g. objects, solid materials, etc., which require specific geometries, dimensions or hull shapes.

[0007] It would therefore be desirable to find an alternative solution to water ballast systems, which avoids all the disadvantages mentioned above and which ensures safe and efficient navigation of cargo ships. DESCRIPTION OF THE INVENTION

[0008] The subject of the invention is a ballastless vessel, in particular a ballastless cargo vessel, which comprises a hull having a longitudinal upper body, which serves as a cargo hold, and a longitudinal lower body, which serves as a buoyancy correction volume, the lower body being located below the upper body. The upper body and the lower body have a substantially rectangular cross-section along the length of the hull, but the lower body has smaller dimensions (it is narrower and shallower) than the upper body. Thus, the cross-section at the master has two bilge wells per side, instead of one. The concept of the ballast effect on the conventional design (with ballast) is replaced by the practical reduction of the waterline volume of the hull. More particularly, the upper body and the lower body may have a substantially rectangular cross-section along the length of the cargo space of the vessel, for example the hold, while the bow section and the stern section of the vessel may have a substantially similar or different cross-section. For example, the bow section of the vessel may be a bulbous bow, a clipper bow, a curved bow, or any other type of bow. Said bow section may be designed to reduce the resistance of the hull cutting the water. On the other hand, the stern section of the vessel may be a square or transom stern, a round stern, a fan stern, a merchant stern, or any other type of stern.

[0009] The lower body is connected to the lower wall of the upper body in the central part of the ship (under the hold). The lower part of the two bodies may have a floor rise. This floor rise may vary along the length of the ship. The connection between the upper body and the lower bodies at the bow and stern may become continuous tangent and occur at the side walls. Therefore, the upper and lower volumes may be one at the front and end of the ship.

[0010] The upper body and the lower body may be further connected to each other by means of internal structural frames, pillars or the like. The lower body provides the cross-section with marked concave areas on its edges. The height of the upper body relative to the height of the lower body may depend on the difference between the maximum displacement and the minimum displacement of the vessel. For example, the greater the difference between the maximum displacement and the minimum displacement of the vessel, the greater the height of the lower body relative to the height of the upper body. In some examples, the height of the upper body relative to the keel depth of the vessel may be between 45% and 85%. Thus, in such examples, the height of the lower body relative to the keel depth of the vessel may be between 55% and 15%.To compensate for this difference between the maximum and minimum displacement of the vessel, the maximum waterline width (waterline width at the upper body) of the vessel can be further varied, so that the greater this difference, the greater the maximum waterline width of the vessel. Alternatively, the waterline width and draft of the vessel can be varied together to compensate for this difference.

[0011] The distribution of the volume of the lower body modifies the vertical distribution of the buoyancy of the hull, which results in a greater draft of the vessel in light (unloaded) condition than that of other known vessels having different geometries.

[0012] The ballastless cargo ship further comprises at least one cargo space, in other words, at least one volume for transporting the cargo, such as the cargo hold, arranged at least in correspondence with the upper body for at least storing the cargo. This hold may completely occupy the space defined by the upper body, or may completely or partially occupy the space defined by the upper body and also partially occupy the space defined by the lower body of the ship. The cargo space may also protrude from the upper body so as to partially occupy the deck of the ship.

[0013] The ballastless cargo vessel also includes void spaces at least partially in correspondence with the lower body. These void spaces serve as flotation tanks for the vessel. A portion of these void spaces may further be used to store fuel tanks, piping systems or a trim compensation system as described below, among other systems or elements of the vessel. By way of example, the ratio between the volume of the void spaces and the maximum volumetric displacement of the vessel may range from 0.1 to 0.45, although other ratios may be achieved depending on the particular design of the vessel.

[0014] The cross-section of the lower body may comprise inclined side walls which may meet and be connected to the lower wall or to the side walls of the upper body. These inclined side walls may be substantially planar (the inclined side walls may form a substantially constant angle with respect to the water plane) or may be curved (the inclined side walls may form a variable angle with respect to the water plane). In any case, the equivalent average slope of the inclined side walls (obtained for an equivalent volume of the lower body having completely planar inclined side walls) may be between 0.5° and 85° with respect to the horizontal.In some embodiments, the lower body further includes a flat bottom (also known as a flat bottom wall) located at a central portion of the bottom of the hull and along the length of the hull, and more preferably along the length of the cargo spaces, such that sloping side walls are formed on both sides of the flat bottom such that the lower body has a substantially truncated V-shaped cross-section. This truncated V-shaped cross-section of the lower body is substantially similar to an inverted trapezoidal cross-section. The lower body may also include sloping wall portions formed at an apex of both side walls to join the bottom wall of the upper body.

[0015] The shape of the cross-section in the essentially prismatic length of the ship thus defined forms four separate bilge wells instead of two in other known vessels with different ship geometries. These bilge wells may be rounded or the side and bottom walls that form them may meet at an angle.

[0016] The ballastless cargo vessel is defined such that, for a predefined parameter, the parameter being selected from a group comprising a maximum draft (Tmax), a minimum draft (Tmin) and a maximum waterline width (B max) of the vessel, the geometry of the vessel is defined by: i. a ratio (%Bmax) between the width of the flat bottom wall of the vessel and the maximum waterline width at the waterline area of ​​the vessel which is between 0 and 0.7, ii. a ratio (%Tmax) between the submerged draft of the upper body (in other words, the vertical distance corresponding to the submerged part of the vertical walls of the upper body) and the maximum draft of the vessel which is between 0 and 0.8, and iii. a master cutting coefficient (Cm) of the vessel defined as follows: _ i+%Tma.+%Bmtlx- %Tmax*%Bmax . 2 — " 2 which is between 0.65 and 0.85.

[0017] In this document, the master's cross-section coefficient of a ship designates the ratio between the surface area of ​​the master's cross-section of the ship, for a defined draft, and the surface area of ​​the rectangle which contains said surface area of ​​the master's cross-section of the ship, the width of the rectangle corresponding to the width outside the member of the ship and the height of the rectangle corresponding to the previously defined draft.

[0018] Then, the coefficient %Bmax which was defined as being the ratio between the width (b) of the flat bottom of the ship and the maximum waterline width (Bmax) of the ship at the level of the waterline area of ​​the ship is as follows: = _h_ / bL,max R

[0019] Similarly, the coefficient %Tmax which was defined as being the ratio between the submerged draft (t) of the upper body and the maximum draft of the vessel (Tmax) is as follows: %T = _L_ max t 1 max

[0020] The cross-section of the lower body maintains sufficient draft and stability in light conditions and prevents damage to the propeller due to cavitation without the need for a ballast system. It also reduces hull resistance and improves propulsion efficiency. The presence of two additional bilge wells increases eddy roll damping. The volume of voids in the lower body allows the maximum draft of the vessel not to be exceeded (the voids act as a float when the vessel is loaded). The lower body can also have a shape that changes along the length of the body, becoming more pointed at the bow. This longitudinal distribution of the volume of the lower body modifies the position of the center of flotation of the hull according to changes in draft.

[0021] Furthermore, by having an upper body with a substantially rectangular cross-section along the entire length of the vessel and avoiding the use of side ballast tanks, the space occupied by the cargo space can be maximized in said upper body (the cargo space can have a width that substantially corresponds to the waterline width of the vessel), compensating for any space loss in the lower body.

[0022] The block coefficient of a vessel is defined as the ratio of the underwater volume of the vessel to the volume of a parallelepiped block defined by the length between perpendiculars, the width (waterline width) and the depth (draft) of the vessel. In some embodiments, this block coefficient of the vessel depends on a value of the angle of the side walls of the lower body, which may be inclined, relative to the baseline.

[0023] For example, for a predefined Bmax and Tmax and constant values ​​of t and %T max (only b and %Bmax are modified), a larger angle of the inclined side walls relative to the flat bottom implies a higher block coefficient and vice versa. In other examples, for predefined values ​​of Bmax and Tmax and constant values ​​of b and %Bmax (only t and %Tmax are modified), a larger angle of the inclined side walls relative to the flat bottom implies a lower block coefficient and vice versa. Furthermore, the cross-section coefficient and the block coefficient of a vessel are related to each other. In other words, the lower the cross-section coefficient, the lower the block coefficient, and vice versa.

[0024] In some cases, the block coefficient (Cb) is defined as follows: %Tmax + ( \-%Tmax) • %Aflnaimax + ^^ _ . (l-%7 “ 2 = 1 ' ~ 2 ' and is between 0.52 and 0.72, where %Afloatmax is the ratio of the flat bottom area (Aflatbottom) of the lower body of the vessel to the maximum waterline area (Afloatmax) of the vessel. The resulting block coefficient (Cb) of the vessel depends on the difference between the maximum displacement and the minimum displacement of the vessel.

[0025] Then, the coefficient %Afloatmax which was defined as being the ratio between the surface of the flat bottom (Aflatbottom) of the lower body of the ship (if the ship does not have a flat bottom, this ratio will be zero) and the surface of the maximum waterline (Afloatmax) of the ship is defined as follows: ^^floatmeuc ~ 4 . JJ la-if mas

[0026] In some embodiments, when the vessel is at its minimum draft (minimum weight), the lower body is at least partially submerged and, when the vessel is at its maximum draft (maximum weight), the lower body is fully submerged and the upper body is partially submerged.

[0027] In some embodiments, the at least one cargo space is a hold, and more particularly a caisson-type hold. In these embodiments, due to the absence of side ballast tanks in the vessel, the hold may have a width that substantially corresponds to the waterline width of the vessel along the length of the vessel. Therefore, the hold may maximize the space occupancy within the vessel. Then, a reduction in the keel depth of the hold due to the presence of the lower body may be compensated for by the increase in the width of the hold.

[0028] For caisson-type holds, the influence on the hydrodynamic parameters of the vessel of the transition between the flat bottom of the lower body and the side walls of the upper body is particularly important since it is of interest to achieve the maximum value (width over member) with the smallest possible draft, given that the caisson-type hold must be placed as low as possible in the vessel for reasons of stability and to contribute to the maximum draft not being excessive. Therefore, for these particular caisson-type holds, the side walls of the lower body may have an angle to the flat bottom that is smaller than that of other known types of holds. For example, for caisson-type holds, the inclined side walls may form an angle to the flat bottom of between 0.5° and 85°.

[0029] In some embodiments, the minimum draft of the vessel depends on the propulsion system of the vessel. In other words, the minimum draft may be the draft required for proper immersion of the propellers of the vessel's propulsion system. The minimum draft of the vessel may also depend on the stability and seakeeping requirements of the vessel.

[0030] In some embodiments, the ballastless cargo vessel includes two propellers. In these embodiments, the ballastless cargo vessel may further include two propulsion motors such that, when the vessel is sailing at its minimum draft, only one of the two propulsion motors is configured to drive both propellers, and when the vessel is sailing at a draft greater than the minimum draft, each propulsion motor drives a corresponding one of the two propellers. There are primarily two extreme conditions clearly differentiated loading conditions: empty and fully loaded. When cargo ships are empty (no cargo), the displacement and draft are low, as is the drag of the ship when moving through the water (energy saving). When sailing at full load (maximum deadweight tonnage), the drag of the unballasted cargo ship will be very similar to the drag at sea of ​​the conventional cargo ship. This may imply that the difference in power required to propel the ship in the two conditions is significant. In the unloaded condition, since the draft has been reduced to the minimum necessary for the proper operation of the ship, a single propulsion motor is used to drive both propellers. For any other draft greater than the minimum draft, each of the two propulsion motors is used to drive one of the two propellers.In some examples, the propulsion motors may be diesel-electric propulsion motors, such as ASD (azimuth thruster) type propulsion motors with mechanical transmission (L-drive, Z-drive) or electric transmission, which allow for greater control of the power delivered to each of the propellers. These diesel-electric propulsion motors may be powered by a plurality of generator sets that may operate depending on the power required by the propulsion motors.

[0031] In some embodiments, the hull further comprises a trim compensation system comprising at least two tanks connected to each other by a fluid connection, a fluid, for example fresh water, stored in the at least two tanks being transported (weight transfer on board) between said at least two tanks to maintain the stability of the vessel. This trim compensation system is capable of correcting the list and the trim. The size of the tanks and their location within the ballastless cargo vessel can be optimized to provide sufficient torque with the least possible water.In some examples, there may be at least one tank located near each of the side walls (port and starboard) of the hull, connected to each other by a fluid connection to correct the list of the vessel, and there may be at least one tank located near the bow and another tank located near the stern, connected to each other by a fluid connection, to correct the trim of the vessel.

[0032] In some embodiments, the width of the lower body varies along the length of the hull, preferably being wider near a stern portion of the vessel and narrower near a bow portion of the vessel.

[0033] The cargo vessel described herein avoids the use of ballast water systems and thus eliminates the transport of seawater containing invasive marine species. This solution is therefore more effective than current treatment methods in reducing the potential for introduction of said invasive marine species into other foreign ecosystems. Furthermore, by avoiding ballast water treatment, significant energy savings are achieved. In addition, the installation of tanks, pumps, pipes, pipelines, and other elements of the water ballasting system is avoided, with corresponding savings in terms of installation and maintenance. Another advantage is that the vessel described here is more efficient, as it significantly reduces its drag when moving through the water in an empty state (less displacement, less wetted surface, and less power required). Brief description of the drawings

[0034] A set of drawings is provided to supplement the description and to enable a better understanding of the invention. These drawings are an integral part of the description and illustrate an embodiment of the invention which should not be interpreted as limiting the scope of the invention, but only as an example of an embodiment of the invention.

[0035] The drawings include the following figures: [Fig.lA], [Fig.lB] and [Fig.lC] show different views of a cargo ship without ballast, according to a particular embodiment of the invention. [Fig.2] shows a cross-sectional view of the ballastless cargo vessel of Figure 1 along line AA. [Fig.3A] shows a cross-sectional view of the ballastless cargo ship, according to a particular embodiment of the invention, with the parameters that define the ballastless cargo ship in two dimensions. [Fig.3B] shows a cross-sectional view of the ballastless cargo ship of [Fig.3A], with the parameters that define the ballastless cargo ship in three dimensions. Detailed description of the invention

[0036] Figures 1A-C show different views of a ballastless cargo ship 100, according to a particular embodiment of the invention.

[0037] [Fig.lA] shows a perspective view of the bottom of the ballastless cargo ship 100. The ballastless cargo ship 100 comprises an upper body 101 and a lower body 102 along the entire length of the ship 100. Figures 1B and 1C show a bottom view and a side view of the ship 100, respectively. The upper body 101 and the lower body 102 of the ship 100 have a substantially rectangular cross-section along their central portion, in particular, along the space occupied by the hold (not shown in this figure). The lower body 102 is narrower and shallower than the upper body 101.

[0038] In the bow portion 103 of the ship 100, the shape of the lower body 102 narrows to a point while said lower body 102 may be widened at the stern portion 104 (the lower body 102, at the stern portion 104 is the part of the vessel 100 in which there is a greater concentration of weight, such as machinery, etc.) This allows the vessel 100 to avoid tilting and to decrease drag in the seaway. The geometry of the bow portion 103 of the upper body 101 was chosen to match the geometry of the bow portion 103 of the lower body 102 and thus avoid between the upper body 101 and the lower body 102 the very large "horizontal" surfaces which increase drag and reduce efficiency. These geometries, which become more pointed in the longitudinal direction, minimize tossage. At a certain point, the lower body 102 defines a transition surface between the bottom of the vessel 100 and the upper body 101 leaving a space to place propellers.

[0039] Although the ballastless cargo vessel 100 of Figures 1A-C shows a bow portion 103 and a stern portion 104 having a particular geometry, said bow and stern portions may have an entirely different geometry depending on the particular design of the vessel.

[0040] [Fig. 2] shows a cross-sectional view of the ballastless cargo ship 100 of Fig. 1 along line AA. The upper body 101 of the ship 100 has a substantially rectangular cross-section which is defined by the side walls 105 and the lower wall 111 of the hull and deck 106 of the ship 100. The side walls 105 of the upper body 101 are connected by their lower ends to the lower wall 111 which is itself connected to the side walls 107 of the lower body 102 with the interposition of inclined or curved walls 112 which generate concave surfaces on the outer surface of the hull. These inclined or curved walls 112 define the transition zone between the lower wall 111 of the upper body 101 and the lower body 102. In this embodiment, the side walls 107 of the lower body 102 have a certain inclination relative to the flat bottom 108.The lower body 102 also has rounded lower edges 113 to improve the hydrodynamic conditions of the hull.

[0041] The lower body 102 comprises void spaces 109 which act as floats for the ship 100. These void spaces 109 are dimensioned such that the volume of air in the submerged void spaces 109 is equivalent to the volume of air in the submerged ballast tanks, totally or partially empty, in the loaded state of a conventional ship. For example, the ratio between the volume of the void spaces 109 and the maximum volumetric displacement of the ship 100 may be between 0.1 and 0.45. The ship 100 further comprises a caisson-type hold 110 disposed inside the upper body 101 and which projects slightly above the deck 106 for storing the cargo. This hold 110 has a width which corresponds substantially to the waterline width of the ship 100, and a length which corresponds substantially to the length of the ship 100. In particular, the length of the hold 110 may correspond substantially to the length of the central part of the ship 100, that is to say excluding the bow part 103 and the stern part 104.

[0042] Although the ballastless cargo vessel 100 of [Fig. 2] shows a hold 110 disposed in correspondence with the upper body 101 of the vessel 100, the hold 110 may also partially occupy the space contained within the lower body 101 and / or may protrude above the deck line of the vessel 100. Furthermore, although the ballastless cargo vessel 100 shows a single hold, in some other embodiments there may be more than one hold disposed longitudinally along the length of the vessel, more than one hold disposed transversely to the length of the vessel, or any combination thereof.

[0043] [Fig. 3A] shows a cross-sectional view of a ballastless cargo vessel 200, according to a particular embodiment of the invention, including the parameters that define the geometry of the vessel 200 in two dimensions (2D). [Fig. 3B] shows a cross-sectional view of the ballastless cargo vessel 200 of [Fig. 3A], including the parameters that define the vessel 200 in three dimensions (3D). The cross-sectional view of the ballastless cargo vessel 200 illustrated in Figures 3A-B is similar to the cross-sectional view of the vessel 100 of [Fig. 2].

[0044] The ballastless cargo vessels 200 described herein have been designed with a hull geometry, shape, and buoyancy distribution such that, under any loading condition, the vessel's draft is always between the minimum draft and the maximum draft of the vessel's hull. As used herein, the draft of the vessel's or boat's hull means the vertical distance from the waterline to the bottom of the hull, including the hull thickness. The minimum draft is the minimum water depth at which a vessel can safely navigate while complying with applicable maritime regulations. The minimum draft is normally achieved when no cargo is carried on board.Similarly, the vessel's maximum draft is the maximum water depth at which a vessel can safely navigate while complying with applicable maritime regulations, and is normally achieved at the vessel's maximum permissible deadweight, i.e. when fully loaded.

[0045] The cargo state of the vessel that corresponds to the minimum draft is that in which the total weight of the vessel is as low as possible (Wmin), also known as minimum displacement. In this state, the total weight is the sum of the following weights: - Light displacement (LTD), - Constants (K) = supplies and consumables + crew and effects + oils and spare parts + effects in reserves + miscellaneous), and 10% consumption (fuels and oils in tanks), so that, Wmin = LTD + K + 10% Cons.

[0046] Therefore, for the minimum draft, the vessel must have a volume (Vmin) of the underside of the hull which balances this minimum weight (Wmin): Vmin = Wmin / d ; (d = 1.025 t / m3 ; specific weight of sea water)

[0047] On the other hand, the cargo state of the ship that corresponds to the maximum draft is the one in which the total weight of the ship is as large as possible (Wmax). In this state, the weight of the ship, also known as the loaded (or maximum) displacement, will be the sum of the following weights: - Light displacement (LTD), and - Deadweight (DWT) = Cargo + K + 100% Consumption, so that, Wmax = LTD + DWT = D (full cargo displacement; maximum ship weight)

[0048] Therefore, for the maximum draft, the vessel must have a volume (Vmax) of the underside of the hull which balances this weight (Wmax): Vmax = Wmax / d; (d= 1.025 t / m3)

[0049] The transition between Vmax and Vmin must be made by achieving a growth rate of the bottom volume directly related to the variation of the waterline area of ​​the vessel, in other words, the growth rate of the bottom volume increases with the growth rate of the waterline beam (B(T)) for the considered draft. In this document, the waterline beam (Beam) means the width of a vessel at the widest point measured at the nominal waterline of the vessel. This growth rate of the waterline beam may be limited by certain design restrictions such as a predefined maximum draft, a minimum draft and a maximum waterline width of the vessel, among others.

[0050] The relationship between the draft (T) of the vessel and the volume of the underside of the hull that balances the corresponding weight (W) can also be expressed as a function of the waterline area (Afloat(T)) of the vessel for the draft considered. Then, the condition for the minimum draft (minimum weight) of the vessel can be expressed as a function of the waterline area or as a function of the waterline width as follows: ?Tmin J 0 Afloat (T)dT = Vmin = Wmin / d rTmin Jo B(T)dT = AM min where AMmin is the area of ​​the section defined by the submerged part of the master cut in the minimum draft condition.

[0051] The maximum draft condition (maximum weight) of the vessel can be expressed as a function of the waterline area or as a function of the waterline width as follows: rTmax J 0 Afloat (T) dT = Vmax - Wmax / d rTmax Jo B(T)dT = AM,„x where AMmax is the area of ​​the section defined by the submerged part of the master cut in the condition of maximum draft.

[0052] It is therefore necessary to define the functions Afloat(T) and B(T). These functions can be defined over intervals. In the interval of the functions corresponding to the lower body of the hull, the waterline area and the waterline width increase constantly.

[0053] According to [Fig.3A], the initial data that define the ballastless cargo ship (considering that the waterline width of the ship increases linearly) are: the maximum draft (Tmax), the minimum draft (Tmin), the ratio (%B max) between the width (b) of the flat bottom of the lower body of the ship and the maximum waterline width (Bmax), the ratio (%Tmax) between the submerged draft (t) of the upper body of the ship (i.e. the vertical lateral dimension of the upper body of the ship) and the maximum draft (Tmax), and the maximum waterline width (Bmax). For this particular embodiment, Tmax has been considered as the predefined parameter, i.e. the Tmax of the ship is used as a restriction to obtain the master cutting coefficient (Cm), the %Bmax ratio and the %Tmax ratio.Alternatively, the master cutting coefficient, %Bmax ratio and %Tmax ratio can be obtained by using the maximum waterline width (Bmax) or the minimum draft (Tmin) as predefined parameters (restriction) since all these dimensions (maximum draft, minimum draft and maximum waterline width) are related to each other.

[0054] Knowing the maximum and minimum displacement of the vessel and a given maximum draft (restriction), varying the values ​​of %Bmax and %Tmax between 0 and 0.7, respectively, and establishing that = Cm = (0.65,0.85) All possible solutions can be found to design the cargo ship without ballast. Each solution obtained will have a minimum draft and a maximum waterline width. Then, the lower the %Bmax and the higher the %Tmax, the lower the vessel's midships coefficient and block coefficient. In addition, and consequently, the midships coefficient, as well as the block coefficient, will be lower the more inclined the side walls of the lower body are. The midships coefficient and block coefficient of a vessel are related to each other. In other words, the lower the master cutting coefficient, the lower the block coefficient and vice versa.

[0055] According to [Fig.3B], the initial data that define the ballastless cargo ship (considering that the waterline of the ship increases linearly and that the variation in the waterline is due solely to a variation in the waterline width) are as follows: the maximum draft (Tmax), the minimum draft (T min), the ratio (%Afloatmax) between the surface of the flat bottom (Aflatbottom) of the lower body of the ship and the surface defined by the maximum waterline of the ship (Afloatmax), the ratio (%Tmax) between the vertical lateral dimension (t) of the upper body of the ship and the maximum draft (Tmax), and the maximum waterline width (Bmax).For this particular embodiment, Tmax has been considered as the predefined parameter, i.e. the Tmax of the vessel is used as a restriction to obtain the block coefficient (Cb) (and also the midships coefficient (Cm)), the ratio of the flat bottom area to the maximum area of ​​the vessel's waterline, and the ratio of the submerged draft of the upper body to the maximum draft of the vessel. Alternatively, the ratio (%Afloatmax) and the ratio (%Tmax) of the vessel can be obtained by using the maximum waterline width or the minimum draft as predefined parameters (restriction) since all these dimensions (maximum draft, minimum draft and maximum waterline width) are related to each other.

[0056] Knowing the maximum and minimum displacement of the vessel and a given maximum draft (restriction), varying the values ​​of %Bmax and %Afloatmax between 0 and 0.7, respectively, and establishing that (0.52,0.72) All possible solutions can be found to design the cargo ship without ballast. Each solution obtained will have a minimum draft and a maximum waterline width. Then, the lower the %Bmax and the higher the %Tmax, the lower the block coefficient and the master cutting coefficient of the ship. In addition, and consequently, the block coefficient, as well as the master cutting coefficient, will be lower the more inclined the side walls of the lower body are. The block coefficient and the master cutting coefficient of a ship are related to each other. In other words, the lower the block coefficient, the lower the master cutting coefficient and vice versa.

[0057] The design of the lower body up to the height of the minimum draft (Tmin) of the vessel allows to obtain a growth rate of the volume of the bottom which is directly linked to the variation of the waterline area of ​​the vessel. In other words, the growth rate of the volume of the bottom increases with the growth rate of the width of flotation for the draft considered. Thus, the block coefficient (Cbm) for the minimum draft (Tmin), equivalent to the block coefficient of the lower body up to the height corresponding to the minimum draft, can be defined as follows: DW^O^W^ d t.-H l„,,, where D is the displacement at full cargo (maximum weight of the ship), Wioad is the weight of the cargo carried in the ship, Wcons is the weight of the ship's consumption, d= 1.025 t / m3 (specific weight of sea water), L is the length of the ship between perpendiculars and B is the width over the member.

[0058] Thus, the lower body block coefficient for the minimum draft is determined according to the main dimensions of the ship, the minimum draft required and the deadweight (DWT) and the consumption of the ship (autonomy). We then obtain a value of the lower body block coefficient which depends on the minimum draft of the ship and which the design of the ship cannot exceed, conditioning the maximum value of the ship's block coefficient and therefore the minimum value of its maximum draft.

[0059] The difference between the maximum volume (Vmax) and the minimum volume (Vmin) of the vessel is as follows: V -V =:T*R*(T -T ■ where C'b is the block coefficient of the upper body in the area between the maximum draft (Tmax) and the minimum draft (Tmin) of the vessel. yv _ (^b / A (T -T} I "M v mr f mtu' \ /

[0060] Since V= W / d, then: VV — — TTT 1 v max v min~ d — l. u y1 max 1 min ivb and then, 'J' __ (OW mjn) I' max ~ d*L^B:^rh min (D-Wmi„)=Wlmd + Vl,9*Wa„ ' load T ■ 2 max d*L^Ch + 1 mm

[0061] This therefore means that the maximum draft of the vessel can be determined on the basis of the main dimensions of the vessel, the minimum draft required and the deadweight (DWT) and consumption of the vessel (autonomy).

[0062] From formulas (1) and (2), we can obtain: v \ F max I 3| Vmax+L*B»1\ / which provides the ship's block coefficient as a function of the block coefficient of the

[0063]

[0064]

[0065]

[0066]

[0067] lower body up to its minimum draft and the block coefficient of the upper body between its minimum draft and its maximum draft. If we consider that the cutting coefficient at the master of the upper body (C'm) of the ship is equal to 1 (this simplification makes it possible to maximize the value of the block coefficient of the ship and therefore to obtain a minimum Tmax, which means that the maximum waterline width is reached at the minimum draft or even at a draft less than the minimum draft), the block coefficient of the upper body is equal to the prismatic coefficient of the upper body (C'p), cb^c^cm=Cp With the prismatic coefficient of the vessel (Cp) and the prismatic coefficient of the lower body (Cpm), we can obtain the prismatic coefficient of the upper body (C'p): C 'p\AM - AMmif)=CP AM - Cpm*AMmin AMmin*Cpm = AM^CP^ where AM is the cross-sectional area at the master of the ship in the condition of maximum draft (TmaA and AMmin is the cross-sectional area at the master of the ship up to the minimum draft By applying the simplification C'b =C'P, we can obtain the block coefficient of the ship on the basis of the prismatic coefficient of the ship and the prismatic coefficient of the lower body: C* ma* h —VV - ,z K':r' । T Cp " Cm n 1 fnin We can then deduce the maximum draft: vvv ■ 'p __ v mmi __ 1 mat__mm , 2 ma* “ L*B*Cb — L*B*CP “ L*B*C!ml 1 min The rest of the vessel parameters can be derived, with the predefined restrictions, from this block coefficient and the maximum draft. The prismatic coefficient of the lower body Cpm is limited and cannot be less than l-AM*(l-Cp) / AMmin since C'p is less than 1. i ■< t AM ( 1- c A 1 1 -^1 A 'inm X i ' Since Cpm has a minimum value that cannot be reduced, and the block coefficient Cb decreases with increasing Cpm, the value of Cpm should be as close as possible (taking into account the value of C'p) to its minimum value (the block coefficient should be as high as possible to obtain the lowest possible maximum draft).

[0068] Therefore, the value of the block coefficient has an upper limit that cannot be reached. This maximum value corresponds to a value of the prismatic coefficient of the lower body equal to the minimum value that it can have, i.e., Cpm = C ( min ) which makes the value of the prismatic coefficient of the upper body equal to 1, C'^l. Q(max) = ymarvJ+LBTniin =

[0069] Thus, the maximum draft of the vessel has a lower limit which cannot be reached and the value of which is: T / mr'n A _ 1 ma t^isùn) > T _ 1 T — ' mm~ d*L*B * min

[0070] The main characteristics of the vessel will be within the limit values ​​described above.

[0071] By way of example, a table showing various parameters of a ballastless cargo vessel, according to a particular embodiment of the invention, a conventional slow-moving cargo vessel and a standard cargo vessel (both incorporating ballast systems), is provided. Ranges of ballast-free cargo ships Slow-moving cargo ship Standard ship Ballast-free cargo ship Maximum ballast-free cargo ship B / T 1.35-3 2.1-2.3 2.3 1.9 1.4 cb 0.52-0.72 0.65-0.73 0.74 0.69 0.54 cm 0.65-0.85 0.97-0.995 0.94 0.79 0.67

[0072] The parameters compared in this table are the ratio (B / T) between the waterline width (B) and the draft (T), the block coefficient (Cb) and the midships coefficient (Cm) of the ships. The values ​​of the ratio (B / T), the midships coefficient (Cm) and the block coefficient (Cb) were obtained on the basis of the formulas described above. For the definition of the dimensions and proportions indicated in the table, it was considered that the waterline length and width remained substantially constant for the ballast-free cargo ship. Thus, the most important dimensions to be defined are the draft and the keel depth of the ballast-free cargo ship.

[0073] The column "Ballast-Free Cargo Vessel Ranges" refers to the values ​​between which the ballast-free cargo vessel described in this document falls. The column "Slow-Sailing Cargo Vessel" refers to the valuesbetween which a conventional slow-moving cargo ship with a ballast system is located. The column "Standard ship" refers to the values ​​of a particular conventional cargo ship with a ballast system. The values ​​in the columns "Slow-moving cargo ship" and "Standard ship" are known from the prior art (Ship design: Methodologies of Preliminary Design, Papanikolaou 2014). The column "Cargo ship without ballast" refers to the values ​​of a particular cargo ship without ballast, as described in this document, in which, in order to obtain the indicated parameters, the keel depth of the ship has been modified. The values ​​in the column "Maximum cargo ship without ballast" were obtained for a maximum draft (restriction) of 150% of the maximum draft of a conventional cargo ship.In particular, the column "Maximum Zero Ballast Cargo Ship" shows values ​​of Zero Ballast Cargo Ship in which only the keel depth of the ship has been modified and the lower body has a V-shaped deadrise (in other words, there is no flat bottom in the lower body and the lower body has a triangular cross-section).

[0074] The (B / T) ratio of the ballastless cargo vessel as described herein is between 1.35 and 3 when the keel depth of the vessel is substantially changed instead of the waterline width, i.e., the maximum draft of the vessel is increased. When the waterline width is substantially changed and not the keel depth (to achieve a maximum draft similar to that of a conventional vessel, i.e., a vessel with a ballast system), the (B / T) ratio is between 2 and 3. The particular value of the (B / T) ratio will depend on the difference in displacement of the vessel due to the different loading conditions and the particular geometry of the vessel. Since only the keel depth, or the waterline width, or both can be changed, a wide range [1.35-3] is obtained for the (B / T) ratio.Then, the design of the ballastless cargo ship can be defined to achieve a solution in which the ratio (B / T) would be substantially equal to the values ​​of this ratio for the conventional ship (e.g., the standard cargo ship or the slow-moving cargo ship), the keel depth and the waterline width of the ballastless cargo ship being greater than the normal values ​​of a conventional ship with similar characteristics. The values ​​of Cb and Cm are not affected by the value of the ratio (B / T) since they are affected by the value of the product (BxT).

[0075] If we compare the values ​​obtained for the cargo ship without ballast with the values ​​obtained for conventional or standard ships, we see that the draft and / or the waterline width of the cargo ship without ballast are higher. Thus, the multiplication of the waterline width and the draft is higher than in conventional ships (having ballast systems). The block coefficient, and therefore the cutting coefficient at the master is lower than in conventional vessels.

[0076] As used herein, the term "includes" and its derivatives (such as "comprising", etc.) are not to be understood in an exclusive sense, i.e., these terms are not to be interpreted as excluding the possibility that what is described and defined may include other elements, steps, etc. The term "other", as used herein, is defined as at least a second or more. The term "coupled", as used herein, is defined as being connected, whether directly without any intervening element or indirectly with at least one intervening element, unless otherwise indicated. Two elements may be coupled mechanically, electrically, or communicatively connected by a channel, pathway, network, or communication system.

[0077] The invention is obviously not limited to the specific embodiments described herein, but also encompasses all variations that may be contemplated by any person skilled in the art (e.g., with respect to the choice of materials, dimensions, components, configuration, etc.), within the general scope of the invention as defined in the claims.

Claims

Claims

1. A ballastless cargo ship (100), characterized in that the ship (100) comprises: a hull comprising a longitudinal upper body (101) and a longitudinal lower body (102), the lower body (102) being located below the upper body (101), the upper body (101) and the lower body (102) having a substantially rectangular cross-section along a length of the hull, the lower body (102) being of smaller dimensions than the upper body (101); and at least one cargo space (110) arranged at least in correspondence with the upper body (101) for at least storing cargo, and void spaces (109) at least partially in correspondence with the lower body (102); the lower body (102) comprising respective side walls (107) which are connected to a bottom wall (111) of the upper body (101);and for a predefined parameter, the parameter being selected from a group comprising a maximum draft (Tmax), a minimum draft (Tmin) and a maximum waterline width (Bmax) of the vessel, a geometry of the vessel is defined by: i) a ratio (%Bmax) between a width of a flat bottom wall of the vessel and a maximum waterline width at the waterline area of the vessel which is between 0 and 0.7, ii) a ratio (%Tmax) between a submerged draft of the upper body and a maximum draft of the vessel which is between 0 and 0.8, and iii) a cutting coefficient at the master (Cm) of the vessel defined as follows: ” ? which is between 0.65 and 0.85.;

2. A vessel (100) according to claim 1, wherein the lower body (102) comprises the flat bottom wall (108) located at a central portion of a bottom of the hull and along the length of the hull, and inclined wall portions (112) formed at a top of the two side walls (107) to join the bottom wall (111) of the upper body (101).

3. A vessel (100) according to any preceding claim, wherein a block coefficient (Cb) of the vessel is defined as follows: 1 " 2 and is between 0.52 and 0.72, where %Afloatmax is the ratio between an area of the flat bottom wall (108) of the lower body (102) and an area defined by a maximum waterline of the vessel.

4. A vessel (100) according to any preceding claim, wherein when the vessel is at its minimum weight the lower body (102) is at least partially submerged and when the vessel is at its maximum weight the lower body (102) is fully submerged and the upper body (101) is partially submerged.

5. A ship (100) according to any preceding claim, wherein said at least one cargo space (110) is a hold, and more preferably a caisson-type hold.

6. A vessel (100) according to any preceding claim, wherein said at least one cargo space (110) has a width that substantially corresponds to the waterline width of the vessel along the length of the vessel.

7. A vessel (100) according to any preceding claim, wherein the minimum draft of the vessel is dependent on a propulsion system of the vessel.

8. A vessel (100) according to any preceding claim, comprising two propellers.

9. A vessel (100) according to claim 8, comprising two propulsion motors such that when the vessel is moving with the minimum draft, only one of the two propulsion motors is configured to drive both propellers, and when the vessel is moving with a draft greater than the minimum draft, each propulsion motor drives a corresponding one of the two propellers.

10. A vessel (100) according to any preceding claim, wherein the hull comprises a trim compensation system having at least two tanks connected to each other by a fluid connection, a fluid stored in the at least two tanks being transported between said at least two tanks to maintain stability of the vessel.

11. A vessel (100) according to any preceding claim, wherein the upper body (101) and the lower body (102) have a substantially rectangular cross-section along a length of said at least one cargo space (110) of the vessel.

12. A vessel (100) according to any preceding claim, wherein the lower body (102) comprises lower edges rounded (113).

13. A vessel (100) according to any preceding claim, wherein the width of the lower body (102) varies along the length of the hull, preferably being wider near a stern portion (104) of the vessel and narrower near a bow portion (103) of the vessel.

14. A vessel (100) according to any preceding claim, wherein a master section of the vessel comprises two bilge wells per side.

15. A vessel (100) according to any preceding claim, wherein the side walls (107) of the lower body (102) are inclined relative to the flat bottom wall (108) of the lower body (102).

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