JP2021176733A - Hull of marine floating structure - Google Patents

Abstract

To provide a hull structure capable of being able to secure required safety facilities, traffic routes, and workability while maintaining a gross tonnage within a specified range and ensuring a stability of the hull and a rolling prevention performance.SOLUTION: A cross section of a hull 10 of a marine floating structure consists of a widening width area where a hull width on a deck 15 side is maintained to a certain depth and then gradually decreases as it gets deeper, and a narrowing width area where the hull width gradually decreases toward a bottom of a ship bottom side so that the gross tonnage measure of the hull is maintained at a specified value. A full load water line 25 is set in a portion where the hull width in the widening width area is maintained to a certain depth, and a light load water line 26 is set in the narrowing width area. Here, the measure of the gross tonnage is defined by the Ordinance for Enforcement of Act on measure of the gross tonnage of a ship.SELECTED DRAWING: Figure 1

Description

The present invention relates to the hull structure of marine floating structures such as ships, barges and piers.

The hull of a marine floating structure such as a ship, barge, or pier adopts an appropriate structure according to its use and function, but the cross-sectional shape of the hull is generally formed in a box shape. However, improvements to the bow, stern, or bottom of the hull have been proposed for the purpose of reducing hull resistance, improving hull roll stability performance, improving course stability performance, etc., and such parts are not necessarily box-shaped.

For example, Patent Document 1 has proposed a ship for ocean voyage and a hull of the ship for ocean voyage, which has excellent stability and can effectively control rolling, and has a speed of 15 knots. .. That is, it is a hull of a drainage type pelagic vessel, and has a substantially rectangular barge-shaped constant cross section with a flat bottom in the hull center section below the waterline, and a bow that extends from the hull center section and converges. The bow has a curved transition between the bottom and each side of the hull, and the transition between the bottom and the side along the curved bottom of the central section of the hull is relatively sharp. , A hull with a radius of curvature of less than 0.5 m has been proposed.

Further, in Patent Document 2, the cross-sectional shape of the hull is a substantially triangular shape with the keel line as the apex and the set water line as the base in the cross-sectional shape of the stern portion following the main body portion having a substantially box shape. A hull having a shape in which the height of the stern gradually increases toward the stern end has been proposed. It is said that this hull can improve the course stability performance and reduce the impact of waves related to the pitching of the hull.

Patent Document 3 describes a hull structure in which the hull has a bow portion, a hull parallel portion connected to the rear of the bow portion, and a hull portion connected to the rear of the hull parallel portion. A hull structure has been proposed in which the cross-sectional shape of the bilge portion of the parallel portion is linear, and the cross-sectional shape of the bilge portion of the bow portion and the stern portion includes a curve. It is said that this hull structure can satisfy the stability of rolling during operation and the resistance performance during movement, and can suppress the manufacturing cost.

On the other hand, although the cross-sectional shape of the hull is box-shaped as a whole, a proposal has been made for a hull having a cross-sectional shape different from the hull shape described in Patent Documents 1 to 3. For example, Patent Document 4 proposes an underwater tour boat in which a pair of left and right float chambers are formed on both sides of an upper half of an underwater cabin extending in the front-rear direction. This underwater tour boat is said to have high restoring force and stability against the inclination of the hull, and it is said that it will surely restore even if the hull is tilted 90 degrees. In addition, it is said that the inundation of the underwater cabin will stop once it reaches the draft line.

In Patent Document 5, a hull having a container accommodating space inside and a main loading surface for loading a container is formed on the upper surface, and a hull installed on both sides of the hull, corresponding to the main loading surface on the upper surface. A container ship is proposed in which a sub-loading surface on which a container can be loaded is formed, and two additional structures whose lower edge extends below the light load waterline of the hull are provided. It is said that this container ship can increase the container load and improve the stability of navigation.

Special Table 2002-526323 Gazette Japanese Unexamined Patent Publication No. 2018-122711 JP-A-2018-131173 Japanese Unexamined Patent Publication No. 6-278683 Japanese Unexamined Patent Publication No. 2011-219081

Based on treaties and protocols concluded through the International Maritime Organization (IMO), the law is amended for the purpose of ensuring the safety of ships, protecting and improving the environment, or improving the living environment of crew members, and the amendments to ships are made. A hull structure that complies with the law is required. For example, the 2003 decree of the 1988 Protocol on the 1966 International Convention on Full Waterlines was developed. It is conceivable to increase the size of the hull in order to secure the required cargo compartment in response to the demands such as strengthening the protection of the bow and the safe passage of seafarers under such laws and regulations. However, the gross tonnage of ships is used as the main index to express the size of ships in Japan's maritime relations system (Act on Measuring Tonnage of Ships), and the hull structure of recent ships is regulated by law. It tends to be set within the upper limit of the gross tonnage category. For this reason, it is difficult to adopt an appropriate hull structure according to the application and function as shown in Patent Documents 1 to 5, and it is possible to comply with the revised law while maintaining the total ton number within a predetermined range. Hull structure is required.

In view of such conventional problems or requirements, the present invention maintains the total ton number within a predetermined range, secures the stability of the hull and the rolling prevention performance, and requires the required safety equipment, traffic route, or workability. The purpose is to provide a hull structure that can secure the above.

In the hull of the marine floating structure according to the present invention, the cross section of the hull is maintained at a certain depth on the deck side, and then gradually decreases as the depth becomes deeper, and the measurement of the total ton number of the hull is a predetermined value. It consists of a narrowing area where the width of the ship gradually decreases toward the bottom of the ship so that it is held at the bottom of the ship. It is set in the narrowing area portion. Here, the measure of gross tonnage is based on the law enforcement regulations regarding the measure of tonnage of ships.

In the above invention, the hull has a double bottom structure, and the main part of the portion where the total ton number decreases with the gradual decrease in the width of the ship in the narrowing region can be located in the double bottom structure portion.

In addition, the buoyancy improvement fraction a1 in which the ship width is maintained at a constant depth within the range of the widening range exceeding the standard ship width that holds the measurement of the total ton number of the hull at a predetermined value, and gradually decreases as the ship width becomes deeper. The ratio with the connection fraction a2 to be connected can be set to a2 / (a1 + a2) = 0.2 to 0.4.

Further, in the above invention, the hull has a double bottom structure including a tank for liquid cargo, and the bottom surface, the side surface and the top surface of the tank have the inner bottom plate and the ship side outer plate of the double bottom structure, respectively. It is formed by an inclined side inner plate and a partition deck provided along the line, and the cross-sectional shape can be an isosceles trapezoidal shape.

Further, the hull according to the present invention is a hull having a double bottom structure provided with a tank for liquid cargo, and the bottom surface, side surface and top surface of the tank are each of the double bottom structure. The hull can be formed by a bottom plate, an inclined side inner plate and a partition deck provided along the ship side outer plate, and has an equal cross-sectional shape. In this hull, the lower portion of the inclined side inner plate may be bent toward the hull center line and joined to the inner bottom plate.

According to the present invention, there is provided a hull structure capable of ensuring necessary safety equipment, traffic routes or workability while maintaining the total ton number within a predetermined range and ensuring the stability and rolling prevention performance of the hull. Can be done. The hull is not limited to ships, but can be applied to marine floating structures such as barges and piers. Further, the hull according to the present invention can provide a hull having a low center of gravity height of the hull and excellent restoring force in a ship carrying liquid cargo.

It is a drawing which shows the cross section of the hull which concerns on this invention. It is a cross-sectional view of the hull according to the present invention, and is a drawing of an example in which an offsetting fraction of a width reduction region is provided in a double bottom structure portion. It is a cross-sectional view of the hull according to the present invention, and is an example drawing of a ship side outer plate in which the width of the ship decreases linearly. It is a cross-sectional view of the hull according to the present invention, and is a drawing of an example in which a ship side outer plate whose width is linearly reduced is provided, and an offsetting fraction of a width reduction region is provided in a double bottom structure portion.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows a cross section of a hull according to the present invention. The hull 10 has a widening area A whose cross section is maintained at a certain depth on the deck side and then gradually decreases as it gets deeper, and the bottom side of the hull 10 so as to keep the measurement of the total ton number of the hull 10 at a predetermined value. It consists of a narrowing area B where the width of the ship gradually decreases toward the bottom of the ship. By offsetting the widening area A and the narrowing area B, the measure of the total ton number of the hull 10 is maintained at a predetermined value. Then, the full load waterline 25 is set in the portion where the ship width of the widening area A is maintained at a constant depth, and the light load waterline 26 is set in the portion of the narrowing area B. Here, the measure of gross tonnage is based on the law enforcement regulations regarding the measure of tonnage of ships. The plane shape of the hull 10 has a known shape, and the cross section is symmetrical with respect to the center line of the hull shown in FIG.

As shown in FIG. 1, the outer shape of the hull 10 is defined by the bottom skin 11, the ship side skin 13, and the deck 15. The deck 15 is the upper deck or bulkhead deck, and if the hull 10 is equipped with a tank for liquid cargo, it is the bulkhead deck. If the hull 10 has a double bottom structure, it has an inner bottom plate 12. The hull (111, 121, 131) indicated by the alternate long and short dash line shows the cross section of the conventional hull, and the outer shape is defined by the bottom outer plate 111, the ship side outer plate 113, and the deck 15. If the hull has a double bottom structure, it has an inner bottom plate 121.

According to the present invention, when it is difficult to secure a cargo hold or the like similar to the conventional one for reasons such as ensuring the safety of a ship, the stability of the hull and roll prevention are prevented while securing the volume of the cargo hold and the like similar to the conventional one. The purpose is to ensure performance as well. Therefore, the hull 10 is provided with a portion for increasing the hull width and a portion for decreasing the hull width as compared with the conventional hull. The part that increases the width of the ship is the widening area A. The widening area A includes a rectangular portion having a rectangular cross-sectional shape in which the width of the ship is maintained at a constant depth, and an isosceles trapezoidal portion having an isosceles trapezoidal cross-sectional shape that gradually decreases as the depth becomes deeper. In the region where the cross-sectional shape is rectangular, the double shaded portion is a portion for improving the stability and rolling prevention performance of the hull as compared with the conventional hull, and is referred to as the buoyancy improvement fraction a1. In the region where the cross-sectional shape is an isosceles trapezoid, the double shaded portion is a connection fraction a2 provided so that the cross-sectional shape of the entire hull is smoothly connected to the width reduction region B on the bottom side of the hull.

In FIG. 1, point C is a turning point where the widening area A changes to the narrowing area B. That is, C-C is the width of the ship that holds the measure of the total tons of the hull 10 at a predetermined value, which is the width of the conventional hull. The ship width C-C can be said to be the standard ship width. The width reduction region B is a region (hatched portion, offset fraction b) in which the capacity portion (buoyancy improvement fraction a1 + connection fraction a2) increased with respect to the conventional hull is offset. The hull 10 is smaller than the cross section of the conventional hull by the offsetting fraction b. The width reduction region B is provided so as to gradually reduce the width of the ship toward the bottom of the ship, and as shown in FIG. 2, the offset fraction b can be provided with its main portion on the bottom side of the ship. In particular, in the case of the hull 10 having a double bottom structure, it is preferable to provide the offset fraction b so as to be inside the double bottom (double bottom portion). As a result, it is possible to suppress a decrease in the capacity of the cargo hold and the like.

It is preferable that the ship side outer plate 13 is provided so that the portion where the ship width of the widening area A gradually decreases and the portion where the ship width of the narrowing area B gradually decreases have a ship width that decreases linearly. This facilitates the processing of the ship side outer plate 13. However, the ship-side outer plate 13 shown in FIGS. 1 and 2 is bent at the boundary between the buoyancy improving fraction a1 and the connecting fraction a2. This is to make the width of the ship maintained at a certain depth in the widening area A as large as possible.

In the hull 10, the full load waterline 25 is set at a portion where the ship width is maintained at a constant depth as described above. That is, the full load waterline 25 is set in the buoyancy improvement fraction a1 portion. As a result, the stability of the hull 10 and the roll prevention performance can be ensured. The light load waterline 26 is set in the width reduction area B, but it is preferable to set it in the portion of the ship side outer plate 13 where the ship width decreases linearly. An example of a hull having a ship side skin 13 whose width decreases linearly is shown in FIG. 3 or FIG. FIG. 4 shows an example in which the offsetting fraction b is provided on the bottom side of the ship, particularly in the double bottom. In the case of the hull 10 shown in FIG. 3 or FIG. 4, the semi-mounted waterline 27 can be set in the widening area A, which is preferable. For example, depending on the characteristics of the cargo and the characteristics of the customer, the normal load capacity of the ship may be 50% or 80% of the full load capacity. In such a case, the semi-mounted waterline 27 can be set in the widening area A, which is preferable. Further, in such a case, the ratio of the buoyancy improvement fraction a1 and the connection fraction a2 can be set to a2 / (a1 + a2) = 0.2 to 0.4.

When the hull 10 according to the present invention is used for transporting liquid cargo, the hull 10 is considered to have a double bottom structure. That is, as shown in FIG. 1, the tank for storing the liquid is formed by the inner bottom plate 12 having a double bottom structure, the inclined side inner plate 16 provided along the ship side outer plate 13, and the bulkhead deck 15. The inclined side inner plate 16 has a flat plate shape and is connected to the inner bottom plate 12 and the partition deck 15. This tank has an isosceles trapezoidal cross-sectional shape. The bow side and the stern side of the tank are formed by known bow bulkheads and stern bulkheads, respectively. Such a tank can deepen the center of gravity of the tank and can form a hull having excellent stability.

In FIG. 1, the inclined side inner plate 14 is provided so as to be symmetrical with respect to the hull center line and to have the function of the hull side longitudinal partition wall 141 of the conventional hull. However, a ship-side longitudinal bulkhead can be provided separately from the inclined-side inner plate 14. The inclination angle θ of the inclined side inner plate 14 can be an angle exceeding 90 ° (for example, 150 °). Further, in FIG. 1, the inclined side inner plate 14 has an inclined flat plate shape and is joined to the inner bottom plate 12, but when the lower portion thereof is refracted toward the center of the hull based on the safety standard (IMUCO rule) ( There is a refracting part 14a). For example, if the hull is a liquid chemical carrier, it is classified into ship type 1, 2 and 3 according to the danger of cargo, and in ship type 1 and 2, the distance from the outer panel to the cargo loading location is 760 mm or more. This is because it is stipulated that it must be secured.

The hull 10 according to the present invention has been described above. The hull 10 according to the present invention can be used not only for ships but also for marine floating structures including barges, piers and the like. Barges are effective as a means of ensuring the stability of the hull as well as the required space when there are height restrictions.

10 hull
11 Ship bottom skin
12 Inner bottom plate
121 Inner bottom plate
13 Ship side skin
131 Ship side skin
14 Inclined inner plate
141 Ship side longitudinal bulkhead
15 deck
25 full waterline
26 Light load waterline
27 Half-mounted waterline

Claims (6)

A hull of an offshore floating structure whose cross section holds a widening area in which the width of the ship on the deck side is maintained at a certain depth and then gradually decreases as the depth becomes deeper, and the measurement of the total ton number of the hull is maintained at a predetermined value. As shown, it consists of a narrowing area where the width of the ship gradually decreases toward the bottom of the ship.
A hull in which a full load waterline is set in a portion where the width of the widened area is maintained at a constant depth, and a light load waterline is set in the narrowed area.
Here, the measure of gross tonnage is based on the law enforcement regulations regarding the measure of tonnage of ships. The hull according to claim 1, wherein the hull has a double bottom structure, and the main portion of the portion where the total ton number decreases with the gradual decrease in the width of the narrowing region is in the double bottom structure portion. .. A buoyancy improvement fraction a1 that maintains a constant depth of the ship width within the range of the widening range that exceeds the standard ship width that holds the measurement of the total ton number of the hull at a predetermined value, and a connection that gradually decreases as the ship width becomes deeper. The hull according to claim 1 or 2, wherein the ratio to the fraction a2 is a2 / (a1 + a2) = 0.2 to 0.4. The hull has a double-bottom structure including a tank for liquid cargo, and the tank has an inclined side whose bottom surface, side surface, and top surface are provided along the inner bottom plate and the ship-side outer plate of the double-bottom structure, respectively. The hull according to any one of claims 1 to 3, wherein the hull is formed of an inner plate and a partition deck, and has an isobaric shape in cross section. A hull having a double bottom structure provided with a tank for liquid cargo, the bottom surface, side surface and top surface of the tank are provided along the inner bottom plate and the ship side outer plate of the double bottom structure, respectively. A hull that is formed by an inclined side inner plate and a partition deck, and has an isosceles trapezoidal cross-sectional shape. The hull according to claim 5, wherein the inclined side inner plate is formed by bending the lower portion thereof toward the center line of the hull and joining the inner plate to the inner bottom plate.

Images