JP7312991B2 - vessel - Google Patents

Description

The present invention relates to ships. More specifically, the present invention relates to a small coastal vessel capable of improving propulsion performance while ensuring dead weight tonnage.

The tonnage that indicates the size of a ship includes gross tonnage, dead weight tonnage, displacement tonnage, etc. Of these, the basis for calculation of ship registration tax, port entry fee, etc. is "gross tonnage", which is the total internal volume of the hull converted to tonnage by a legal formula. Ship-related laws stipulate that the amount of tax increases each time the gross tonnage exceeds a predetermined gross tonnage, such as 200 tons, 500 tons, or 750 tons.

In addition, Article 5, Paragraph 3 of the Law Concerning Tonnage Measurement of Ships stipulates the calculation of the gross tonnage of double-deck ships, which have a second deck below the upper deck, and is given preferential treatment over single-story ships. In addition, the equipment required by the equipment regulations for ships is different with a gross tonnage of 750 tons as a division, and double deck ships with a gross tonnage of less than 750 tons are widely adopted as ships that can be economically constructed, and many related technologies have been published (Patent Document 1 and Patent Document 2).

JP-A-11-348892 Japanese Patent Application Laid-Open No. 2000-289687

By the way, due to the recent rise in fuel costs and growing awareness of global warming, there is a demand for the development of fuel-efficient ships that have less resistance during navigation. Here, the resistance that hinders the navigation of a ship includes wave-making resistance, friction with water, viscous resistance due to eddies, air resistance, and the like. Of these, wave-making resistance is largely affected by the shape of the bow, and viscous resistance is largely affected by the shape of the stern. In addition, propulsion performance other than resistance is mainly affected by the shape of the stern.

Therefore, in designing a fuel-efficient ship, it is necessary to fully consider the shape of the bow and stern, as well as the distribution of volume between the midsection, the bow, and the stern, which is important for securing cargo capacity. Although it varies intricately depending on various factors, generally speaking, given the overall length (Lоa) and the overall width (B) of the hull, there is a tendency that the smaller the Lоa/B and the higher the sailing speed relative to the length, the greater the wave-making resistance.

In this respect, for example, in a small ship with a gross tonnage of less than 750 tons, the sailing speed for the captain is faster than that of a large ship, so the wave-making resistance during sailing is inevitably large, and the fuel consumption per required horsepower is large. Furthermore, in coastal vessels, it is necessary to secure a cargo area as much as possible in order to increase transportation efficiency, so the value of Loa/B becomes smaller than that of large vessels, and the wave-making resistance increases.

On the other hand, in order to reduce the environmental load while ensuring the efficiency and economy of transportation, it is necessary to improve the propulsion performance of the hull while suppressing the decrease in the dead weight tonnage. In order to achieve this, the hull should be made longer and slender compared to the width of the hull. However, since the gross tonnage is not the actual weight but the internal volume of the hull calculated by a predetermined formula, if the hull is made slender, the dead weight tonnage will be reduced and the rationality of transportation will be reduced.

Therefore, it is desired to develop a fuel-efficient ship capable of suppressing wave-making resistance during navigation while ensuring dead-weight tonnage for small ships with a gross tonnage of less than 750 tons.

The present invention has been invented in view of the above points, and an object of the present invention is to provide a small coastal vessel that can improve propulsion performance while ensuring dead weight tonnage.

In order to achieve the above object, the ship of the present invention comprises a hull, a first bulkhead extending in the width direction of the hull on the bow side of the center of the hull, a second bulkhead extending in the width direction of the ship on the stern side of the first bulkhead, and a pair of side walls partitioned by a cargo hold, the second bulkhead, a third bulkhead on the stern side of the second bulkhead and extending in the width direction of the ship, and the pair of side walls. an engine room in which a main engine is installed; a rudder installed at a position where the distance from the third bulkhead to the stern perpendicular line is within approximately 5% of the total length of the hull; a propeller installed so as to substantially coincide with the stern vertical line of the rudder; and a propeller shaft transmitting the output of the main engine to the propeller.

Here, by providing the cargo hold partitioned by the first bulkhead, the second bulkhead, and the pair of side walls, the cargo hold consisting of a certain space is formed in the hull, and the dead weight tonnage corresponding to the gross tonnage of the ship can be secured.

In addition, by providing an engine room partitioned by the second bulkhead, the third bulkhead, and the side wall on the stern side of the cargo hold, the main engine serving as the power source can be installed in the engine room. A main engine serving as a power source is composed of, for example, a diesel internal combustion engine or the like, and reciprocating motion by the internal combustion engine can be transmitted to the propeller via a propeller shaft, which will be described later.

In addition, by providing a rudder installed at a position where the distance from the third bulkhead to the stern perpendicular line is within approximately 5% of the total length of the hull, the third bulkhead, which is the bulkhead on the stern side that divides the engine room, can be positioned on the stern side compared to conventional ships.

As a result, the entire engine room and cargo hold can be moved to the stern side without changing the volumes of the engine room and cargo hold compared to conventional vessels. Furthermore, since there is no need to secure a volume for a cargo hold on the bow side, the flexibility of the shape is increased, and the shape of the water plane from both sides to the bow end of the ship can be made narrower and sharper than conventional ships. Therefore, by reducing the amount of displacement on the bow side of the hull and suppressing wave-making from the bow, it is possible to reduce wave-making resistance and improve propulsion performance.

Further, by providing a propeller installed so as to be substantially aligned with the stern perpendicular line of the rudder, the hull can be moved forward and backward by the propulsive force of the propeller.

At this time, since the propeller is installed so as to be substantially aligned with the stern perpendicular line of the rudder, the propeller is installed at a predetermined position between the bow edge and the stern edge of the rudder when viewed from the side of the hull. Therefore, as described above, the distance from the third bulkhead to the stern perpendicular can be shortened, and the engine room can be laid out on the stern side.

Further, by providing the propeller shaft for transmitting the output of the main engine to the propeller, as described above, the reciprocating motion of the internal combustion engine, which is the main engine, can be converted into rotational force, and the rotational force can be transmitted to the propeller, which is the propulsion device.

In addition, when the hull has an upper deck and a second deck, and a gap of a predetermined width is formed between the left and right side walls of the cargo hold and the left and right side walls of the hull from the bottom of the hull to the upper deck, a gap through which workers can pass can be formed in a so-called "double deck ship" consisting of the upper deck and the second deck.

In addition, if the hull plates on both sides of the hull are formed with a bulging portion that bulges outward so that the width of the gap is a predetermined range in the vertical direction with the second deck as the base point, and is about 15% to 35% of the total length of the hull in the stern direction from the bow perpendicular line of the hull in the stern direction.

That is, in a double-deck ship, the gap between the side wall of the cargo hold and the hull plate is stipulated to have a minimum width through which workers can pass. As described above, if the bow shape is sharp with a narrow width, there is a possibility that a narrow gap portion that partially fails to satisfy the minimum width will be formed. In this regard, by forming a bulging portion in the vicinity of the height position of the second deck in the stern direction from the vertical line of the bow where the width of the gap is narrowed over the range of about 15% to 35% of the total length of the hull, it is possible to secure the minimum width that allows workers to pass.

In addition, in the water plane on the second deck, if the line segment connecting the position of the water line on the stern side of about 2.5% of the length between the perpendiculars from the bow perpendicular to the bow end and the line segment passing through the center of the hull are in the range of about 10 to 15 degrees, by arranging the engine room and the cargo hold as a whole on the stern side, it is possible to make the water plane shape narrower and sharper than conventional ships. As a result, as described above, the amount of displacement on the bow side of the hull can be reduced, and by suppressing wave-making generated from the bow, wave-making resistance can be reduced, and propulsion performance can be improved.

Also, if the distance from the stern perpendicular to the rear end of the stern at the planned draft is within approximately 2% of the total length of the hull, the overhang on the stern side at the planned draft can be shortened. Therefore, since the volume of the stern end under the water surface can be increased, a larger amount of dead weight can be secured.

In addition, if the rudder has a substantially cylindrical shape installed around the axis of the propeller so that the propeller is installed inside, the propeller and the rudder are installed at approximately the same position in the fore-aft direction by using the duct-type rudder, so that the engine room can be arranged on the stern side and the overhang on the stern side at the planned draft can be shortened. In addition, the duct type makes it possible to rectify the stern flow and improve the propulsion performance by increasing the rotation efficiency of the propeller due to contraction of the flow.

In addition, the rudder consists of a pair of rudder blades, and when the rudder blades are arranged on the side of the propeller, the propeller and the rudder are installed at substantially the same position in the bow-stern direction by using a gate-type rudder, so that the engine room can be arranged on the stern side and the overhang on the stern side at the planned draft can be shortened. In addition, the gate type rectifies the stern flow, and the constriction of the flow increases the rotational efficiency of the propeller, thereby improving the propulsion performance. Furthermore, at low speeds, the propellers change the direction of the water flow and function as thrusters, improving berthing and docking performance.

INDUSTRIAL APPLICABILITY A ship according to the present invention is a small coastal ship capable of improving propulsion performance while ensuring dead weight tonnage.

1 is a side view of a ship according to an embodiment of the invention; FIG. It is a front cross-sectional view of the vicinity of the center of the hull of the ship according to the embodiment of the present invention. It is an enlarged view of the stern side of the ship which concerns on embodiment of this invention. 1 is an enlarged front view of a ship propeller and a rudder according to an embodiment of the present invention; FIG. It is an enlarged view of the stern side of the conventional ship. It is a comparative view of the horizontal section line of an object ship and a comparison ship. Fig. 3 is a graph showing the increase in drag during waves on a ship; 4 is a graph showing the required horsepower of an object ship and a comparison ship; It is a hull front line drawing of a target ship.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings for understanding of the present invention. In each figure, for convenience of explanation, the direction connecting the bow and the stern of the hull is called the fore-and-aft direction, the direction perpendicular to the fore-and-aft direction in plan view is the transverse direction, and the direction perpendicular to both the fore-and-aft direction and the transverse direction is called the vertical direction. In addition, in the fore-and-aft direction, the bow side is referred to as the front side, and the stern side is referred to as the rear side. In addition, in the ship width direction, the direction facing the outside of the hull is called the outside, and the direction facing the inside of the hull is called the inside.

First, a ship 1 according to an embodiment of the present invention will be described based on FIGS. 1 to 3. FIG. The hull 101 of the ship 1 assumed in the embodiment of the present invention has a total length (Loa) of 85 m or less, a ship width (B) of 15 m or less, a design draft (Td) of 6 m or less, and an upper deck 102 and its lower layer. In addition, Lpp in FIG. 1 indicates the length between perpendicular lines of the bow perpendicular line FP and the stern perpendicular line AP.

The vessel 1 includes a first bulkhead 401 as the bulkhead 4 on the bow end side in the hull 101, a second bulkhead 402 behind the center in the fore-and-aft direction, and a third bulkhead 403 behind the second bulkhead 402 and on the stern end side. The cargo hold 5 is defined by the first bulkhead 401, the second bulkhead 402 and the left and right side walls 404a and 404b, and the engine room 6 is defined by the second bulkhead 402, the third bulkhead 403 and the left and right side walls 404a and 404b.

The left and right side walls 404a, 404b of the cargo hold 5 extend from the inner bottom plate 104 to above the upper deck 102, and have a "double hull structure" in which a predetermined gap 7 is formed between the side walls 404a, 404b and the port and starboard hull skins 105a, 105b of the hull 101. A space sandwiched between the hull bottom plate 106 and the inner bottom plate 104 and a space below the second deck 103 sandwiched between the hull outer plates 105a and 105b and the side walls 404a and 404b are assigned to seawater ballast tanks.

Here, the cargo hold 5 does not necessarily have to be partitioned by the first bulkhead 401 and the second bulkhead 402 . Further partitions may be provided between the first partition 401 and the second partition 402 to divide the cargo hold 5 into small compartments.

Moreover, it is not always necessary to form the partition between the cargo hold 5 and the engine room 6 continuously with the second partition 402 interposed therebetween. For example, a predetermined space may be formed between the cargo hold 5 and the engine room 6 .

The engine room 6 accommodates a diesel engine as a main engine 8 serving as a power source of the ship 1, a fuel tank (not shown) for supplying fuel to the diesel engine, and the like. In addition, when an electric motor is adopted as the main machine 8, a generator or the like associated therewith can be installed.

A propeller 10 is installed behind the engine room 6 via a propeller shaft 9 . The reciprocating motion of the diesel engine as the main engine 8 is converted into rotary motion by the propeller shaft 9 and transmitted to the propeller 10 . In this way, the rotational force of the propeller 10 rotating via the propeller shaft 9 can provide a propulsive force for propelling the hull 101 forward and backward.

A duct type rudder 11 is installed around the propeller 10 so as to cover the entire propeller 10 . The rudder 11 does not have to be of a duct type, and the rudder type is not particularly limited as long as the rudder 11 is laid out on the side surface of the propeller 10 . For example, a gate-type rudder consisting of a pair of rudder blades as shown in FIG.

For comparison with the stern shape of the ship 1 according to the embodiment of the present invention, FIG. 5 shows the stern structure of the conventional ship 1 corresponding to FIG. In addition, in the following description, the ship which concerns on embodiment of this invention is defined as a "subject ship", and the conventional ship is each defined as a "comparison ship." In addition, the main specifications of the comparison ship, such as overall length, width, and design draft, shall be the same as those of the target ship.

In the conventional ship, the rudder 11 is arranged on the stern side of the propeller 10, as shown in _FIG . Therefore, in order to secure a constant volume of the cargo hold 5 partitioned on the bow side of the engine room 6, it is necessary to arrange the first bulkhead 401 (not shown), which is the bulkhead on the bow side of the cargo hold 5, at a position close to the bow end.

On the other hand, in the target ship, the rudder 11 is arranged on the side surface of the propeller 10, so the entire engine room 6 can be arranged behind the comparison ship while maintaining the volume of the engine room 6 as it is. Therefore, the distance l _ER1 between the third bulkhead 403, which is the bulkhead on the stern side of the engine room 6, and the stern perpendicular line AP can be shortened compared to the comparison ship (l _ER1 <l _ER2 ).

In the subject ship, the distance between the third bulkhead 403 and the stern perpendicular line AP is 4 m with respect to the total length of 85 m. That is, by adopting the layout of the rudder 11 and propeller 10 of the target ship, the distance l _ER1 between the third bulkhead 403 and the stern perpendicular line AP relative to the overall length Loa of the target ship can be suppressed within approximately 5%. In this regard, in the comparison ship, the distance l _ER2 between the third bulkhead 403 and the stern perpendicular line AP with respect to the total length Loa is about 6 to 7%.

As described above, in the target ship, the position of the engine room 6 can be moved further aft than in the comparison ship while maintaining the capacity of the engine room 6 . As the engine room 6 moves to the stern side, the cargo hold 5 partitioned in front of it can also move rearward as a whole while keeping its volume constant.

In this way, when the cargo hold 5 of the target ship can be moved rearward compared to the cargo hold 5 of the comparison ship, the first bulkhead 401, which is the bulkhead on the bow side that partitions the cargo hold 5, can also be moved rearward. Therefore, the shape of the bow side is less likely to be affected by the cargo hold 5, so that the degree of freedom in design can be increased.

Furthermore, in the target ship, the distance l _ER1 between the third bulkhead 403 and the stern perpendicular line AP with respect to the total length Loa can be shortened, so the distance from the stern perpendicular line AP to the stern rear end at the design draft Td (stern overhang l _AE1 ) can also be shortened (the target ship is approximately 2 m). A shorter stern overhang 1 _AE1 allows for a greater volume of water at the stern end and thus more cargo capacity. In addition, in the embodiment of the present invention, the stern overhang l _AE1 with respect to the total length Loa of the target ship can be suppressed within approximately 2%.

Next, the bow shapes of the target ship and the comparison ship are compared. FIG. 6 is a diagram showing a comparison of the horizontal cross-sectional lines of the bow shapes of the target ship and the comparison ship at the height position of the second deck 103 (the horizontal cross-sectional line of the target ship is a solid line S1, and the horizontal cross-sectional line of the comparison ship is a broken line S2).

As described above, in the target ship, the first bulkhead 401 can be moved rearward from the position of the comparison ship, so as shown in FIG. On the other hand, in the comparison ship, the first bulkhead 401 is positioned closer to the bow end than in the target ship in order to ensure a constant volume of the cargo hold 5, so the shape of the water plane from both sides to the bow end of the ship projects outside the hull (only the cargo hold 5 of the target ship is shown in FIG. 6).

In the water planes of the second deck 103 of the target ship and the comparison ship, when measuring the angle formed by the line segment connecting the position of the water line approximately 2.5% behind the perpendicular length Lpp from the bow perpendicular FP and the bow end, and the line segment passing through the center of the hull, θ1 = approximately 10 to 15 degrees for the target ship, and θ2 = approximately 20 to 25 degrees for the comparison ship. That is, since the target ship can have a sharp shape with a shorter bow width than the comparison ship, it is possible to reduce the displacement on the bow side and suppress the wave-making resistance Rw.

Here, as a general definition, the total resistance Rt that a ship receives from water is expressed as the sum of the resistance in calm water R and the resistance increase in waves Raw. The resistance in calm water is the sum of the wave-making resistance Rw and the viscous resistance Rv. That is, Rt=R+Raw and R=Rw+Rv.

In addition, the viscous resistance Rv can be expressed as Rv=Rf(1+K), where the frictional resistance Rf of a flat plate (equivalent flat plate) having the same area as the hull and the resistance such as vortices caused by viscosity due to the bulge of the hull are set to K Rf using the shape influence coefficient K.

As shown in FIG. 7, it is known that these components change depending on the ratio of the wave wavelength λ and the length between perpendiculars Lpp. The resistance increase in waves Raw(0) based on the hull motion becomes the largest when λ/Lpp is around 1 where the wavelength λ and the length Lpp between perpendiculars are approximately the same. As a result, the increase in resistance decreases regardless of the length of the wavelength. On the other hand, the resistance increase Raw(1) based on the reflected wave from the bow increases as the wavelength λ becomes shorter, and decreases as the wavelength λ becomes longer.

From the above, in the target ship, the wave-making resistance Rw on the bow side decreases, but the displacement on the stern side increases, so the viscous resistance Rv and the shape influence coefficient K increase. However, in the target ship, the reduction in the wave-making resistance Rw is greater in the movement of this amount of displacement to the stern side, so it is considered that the total resistance Rt is reduced.

More specifically, by making the shape of the bow end sharp, the amount of displacement is reduced, so that the angle of incidence of the waterline at the bow end at the design draft Td becomes smaller, and the resistance increase Raw during waves can be reduced. The smaller the water line incident angle at the bow end, the smaller the resistance increase Raw(0) due to the hull motion and the resistance increase Raw(1) due to the reflection of waves by the hull. When the increase in resistance during waves becomes small, the amount of fuel consumed during navigation is reduced.

In addition, the propulsion efficiency also changes by moving the displacement on the bow side to the stern side. Here, the propulsion efficiency η ^D is composed of the propeller efficiency η ^o , the propeller efficiency ratio η ^r obtained from a water tank test using a model ship, the thrust reduction coefficient 1-t, and the wake coefficient 1-w, and is expressed by the following equation.
η ^D = η ^о・η ^r・(1−t)/(1−w)
Further, the required horsepower PD at the boat speed V (m/s) can be expressed as follows.
PD= _Rt ·V/ ^ηD

Based on the above, Fig. 8 shows the results of estimating the required horsepower of the subject ship and the comparison ship from the results of water tank tests using model ships. As is clear from the results in FIG. 8, the subject vessel can run at the same speed as the comparison vessel with less horsepower, so it can be seen that the subject vessel has improved running performance compared to the comparison vessel.

In the double deck ship, in the vicinity of the height position of the second deck 103 and in the vicinity of the first bulkhead 401, which is the bulkhead on the bow side, the minimum width of the gap for the purpose of allowing workers to pass between the side walls 404a, 404b of the cargo hold 5 and the outer shell plates 105a, 105b is determined to be one frame interval.

On the other hand, if the shape of the bow extending from both sides of the hull 101 to the bow as in the subject ship is a sharp shape with a short width and a tapered tip, there is a risk that the minimum width described above cannot be ensured. Therefore, in the target ship, as shown in FIG. 9, the second deck 103 is approximately 2 m in the upward direction and approximately 1.5 m in the downward direction, and a bulging portion 12 is formed in which the hull shell plates 105a and 105b partially bulge outward over a range of approximately 15% to 35% of the total length Loa of the hull 101 in the stern direction from the bow perpendicular line FP.

The bulging portion 12 can ensure the above-described minimum width of the gap 7 of the second deck 103 of the target ship. The bulging portion 12 has a shape that partially bulges on the front cross-sectional line of the target ship, but as shown in FIG.

As described above, the ship according to the present invention is a small coastal ship capable of improving the propulsion performance while ensuring the dead weight tonnage.

1 ship 101 hull 102 upper deck 103 second deck 104 inner bottom plate 105a, 105b hull outer plate 106 hull bottom plate 4 bulkhead 401 first bulkhead 402 second bulkhead 403 third bulkhead 404a, 404b side wall 5 cargo hold 6 engine room 7 void 8 main machine 9 propeller shaft 10 propeller 11 rudder 12 bulge

Claims (4)

a hull;
A cargo hold partitioned by a first bulkhead extending in the width direction of the hull on the bow side of the center of the hull, a second bulkhead extending in the width direction of the hull on the stern side of the first bulkhead, and a pair of side walls;
an engine room partitioned by the second bulkhead, a third bulkhead extending in the ship width direction on the stern side of the second bulkhead, and the pair of side walls, and in which a main engine is installed;
a rudder installed at a position where the distance from the third bulkhead to the stern perpendicular line is within approximately 5% of the total length of the hull;
a propeller installed so as to substantially coincide with the stern perpendicular line of the rudder;
and a propeller shaft that transmits the output of the main engine to the propeller ,
the hull has an upper deck and a second deck positioned below the upper deck;
Between the side walls of the cargo hold and the hull plates on the left and right sides of the hull, a gap having a predetermined width is formed from the bottom of the hull to the upper deck,
The hull shell plates on the left and right sides of the hull are formed with bulging portions that bulge outward from the hull so that the width of the gap is increased to a predetermined extent over a predetermined range in the vertical direction with the second deck as a base point and a length of about 15% to 35% of the total length of the hull in the stern direction from the bow perpendicular line of the hull.
On the waterline plane of the second deck, the angle formed by a line segment connecting the position of the waterline behind the vertical line of the hull by about 2.5% of the length between the vertical lines of the hull and the bow end, and a line segment passing through the center of the hull is in the range of about 10 to 15 degrees.
vessel. The ship according to claim 1 , wherein the distance from the stern perpendicular to the stern rear end of the planned waterline is within approximately 2% of the overall length of the hull. The ship according to claim 1 or 2 , wherein the rudder has a substantially cylindrical shape installed so as to internally accommodate the propeller around the axis of the propeller. The ship according to claim 1 or 2 , wherein the rudder is composed of a pair of rudder blades, and the rudder blades are arranged laterally of the propeller.

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