KR101271042B1 - Decision method of correction factor for calculating light weight of ship - Google Patents

Abstract

A method of determining the correction factor for calculating the light weight of a vessel is disclosed.
The correction coefficient determination method for calculating the light weight of the ship according to the embodiment of the present invention comprises the steps of determining the non-deformation state shape of the ship, the step of determining the deformation state shape of the ship in the floating state of the ship, For each draft, the step of determining the drainage amount according to the non-deformation shape and the deformation state shape, and obtaining the correction draft using the drainage amount according to the deformation state shape and the deformation state shape, and Determining a correction factor using the average draft or midship hull of the measured bow and stern drafts.

Description

DECISION METHOD OF CORRECTION FACTOR FOR CALCULATING LIGHT WEIGHT OF SHIP}

The present invention relates to a method for determining the correction factor used for calculating the light weight of a ship.

During the design and construction of the ship, tests are carried out to determine the light weight of the ship. Light weight refers to the basic weight of the pure hull itself, including certain fixtures, and is derived from the ship's drainage capacity when no cargo is loaded. That is, the light weight of the ship is obtained by subtracting the weight of the unloaded item from the drainage amount of the ship and subtracting the weight of the unremoved item (including deadweight such as water or oil loaded on board). Here, the amount of drainage means the weight of water that is pushed out when the vessel is floated on the water, and is used in the same concept as the weight of the vessel by the Archimedes principle.

That is, when an object floats in a liquid, the object is subjected to a flotation force equal to the weight of the liquid excluded by the object of Archimedes. In other words, when a ship floats in water, the weight of the ship itself is balanced with the buoyancy force equivalent to the weight of the water excluded by the ship, and it is used to calculate the weight of the ship itself by calculating the drainage, which is the weight of the excluded water. .

Here, due to the weight distribution of the hull itself and the weight of the equipment, such as the engine that is essentially disposed in the ship during the construction of the ship, the bending deformation of the hull occurs, this deformation must be considered in calculating the light weight of the ship.

Referring to the conventional method for calculating the light weight of the ship as follows.

In order to calculate the light weight of the ship, the ship's drainage is first calculated. To calculate the ship's drainage, it is done by launching the ship during construction and then measuring the draft. The displacement corresponding to the measured draft is determined as the displacement of the vessel with reference to the draft for each draft calculated according to the design of the vessel.

At this time, the draft of the ship for referring to the draft for each draft is used by adjusting the value measured from the bow, the stern, and the hull center draft mark. Specifically, first, the difference between the draft of the bow and the stern and the central draft of the hull is obtained to determine the deflection of the hull. After multiplying the hull deflection by three quarters, the hull deflection is corrected, and the draft of the ship for the draft displacement reference is calculated again. Here, the constant 3/4 for modifying the hull deformation amount is an empirical value, which is a value for calculating a correction draft for obtaining roughly the light weight in a state where the ship is not deformed.

However, the conventional method for calculating the light weight of a ship does not faithfully reflect the hull deformation in calculating the light weight of a ship by applying a numerical value of 3/4 uniformly regardless of the deformation amount or the deformation form of the ship. The application of these figures is an empirical application on average, assuming that ships are uniformly deformed into arc shapes. However, the light weight of the actual ship and the light weight calculated by the conventional method is about 1% difference, the reality is, for example, the light weight difference of 400 to 500 tons in the 38,000 ton class ship. This difference leads directly to the reliability of the ship displacement calculation and to the inaccuracy of the design.

In addition, the conventional method for calculating the light weight of such a ship causes inaccurate calculation of the light weight, which causes larger deformation than expected during light weight weight test and keel deflection during construction. In this case, there is a problem that a significant difference occurs in light weight even though it is a linear shape. As a result, a subsequent inclination of the same type of ship may not be recognized as a type of ship, and a new inclination test may be performed to obtain the weight of light weight, etc., and may result in a failure to satisfy the goods weight, which is a guarantee with the owner. have.

The present invention has been made to solve the above problems, and provides a method for determining a correction factor for calculating high light weight in all vessels such as merchant ships, container ships, FPSOs, and the like.

The correction coefficient determination method for calculating the light weight of the ship according to the embodiment of the present invention comprises the steps of determining the non-deformation state shape of the ship, the step of determining the deformation state shape of the ship in the floating state of the ship, For each draft, the step of determining the drainage amount according to the non-deformation shape and the deformation state shape, and obtaining the correction draft using the drainage amount according to the deformation state shape and the deformation state shape, and Determining a correction factor using the average draft or midship hull of the measured bow and stern drafts.

Here, in the step of determining the correction coefficient, the value obtained by subtracting the correction draft from the average draft can be divided by the deformation amount of the ship as the correction coefficient.

Moreover, the value obtained by subtracting the hull center draft from the corrected draft divided by the amount of deformation of the ship can be used as the correction factor.

The amount of deformation may be a value obtained by subtracting the central draft of the hull from the average draft, and may include one or more of deformation by hogging and sagging according to the deformation of the vessel.

The step of determining the deformation state shape of the ship may be determined by measuring the shape of the ship with a three-dimensional measuring instrument.

At this time, the three-dimensional measuring instrument can measure the upper deck of the ship or the hatch coaming top surface.

The correction factor determination method for calculating the light weight of the ship according to the embodiment of the present invention can provide a correction factor for calculating the high light weight that reflects the deformation of the actual ship.

In addition, by measuring the hull deformation amount in the deck or hatch coaming using a three-dimensional measuring instrument, it is possible to easily estimate the actual deformation amount of the ship.

In addition, the amount of deformation is a value that reflects the actual permanent deformation, whereby the correction coefficient is determined so that the correction coefficient can be used regardless of the degree of deformation of the hull, which is different depending on the loading condition. In the case of subsequent lines, it is possible to provide the same high (modified) correction factor as possible.

In addition, by using this correction factor, it is possible to accurately calculate the light weight, thereby reducing the additional cost that may be consumed when the light weight is incorrectly calculated.

1 is a flow chart of a correction factor determination method for calculating the light weight of the ship according to an embodiment of the present invention,
2 is a view illustrating a modified state of the ship,
3 is a calculation table for obtaining correction draft and correction coefficient for each draft according to an embodiment of the present invention,
4 is a plan view of a vessel deformation measurement using a three-dimensional measuring instrument according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

As shown in Figure 1, according to the correction coefficient determination method for calculating the light weight of the ship according to an embodiment of the present invention, first, the shape of the ship's undeformed and deformed state is determined (S1).

The shape of the ship's undeformed state means a shape in a state in which there is no deformation of the ship due to the weight of the hull itself or the weight of various equipments provided in the ship in the basic design section of the ship. The shape of the ship's undeformed state may be determined on the design drawing of the ship, and may be the shape of the ship stored as data on a computer or the like.

In addition, the shape of the deformation state of the ship refers to the shape of the deformation state including the permanent deformation that occurred during the construction and deformation by the weight distribution of the hull itself or the weight of the equipment itself. Deformation of the vessel may include hogging or sagging depending on the deformation form. Hogging refers to a case in which deformation occurs in a convex shape on the upper side of the ship, as shown in FIG. 2 (a). On the contrary, sagging refers to a concave upside of the ship, as shown in FIG. 2 (b). It means the case where deformation occurs in shape. Here, the deformation amount of the ship according to the hogging or sagging shown in FIG. 2 is exaggerated, and varies depending on the size or type of the ship, but a large container ship has a deformation amount of about 350 to 450 mm.

Here, the shape of the deformation state of the ship can be determined in various ways. The shape of the ship's deformed state can be achieved by measuring the deformation of a keel that penetrates the hull along the centerline of the hull while floating on water. In the embodiment of the present invention, by directly measuring the shape of the deformation state of the ship in the manner described below, the accuracy of light weight of the ship is improved more than the case of uniformly assuming the deformation of the hull under the assumption that the hull is bent into an arc shape. It can improve the reliability of the ship and reduce the risk of being judged not to be isomorphic in the same ship.

First, after launching the ship, the ship is not mowed before re-docking and the reference point is set.Then, it is converted into a keel deflection by measuring the spaced distance between the reference point and the bottom of the ship. You can decide. The spaced distance between the reference point and the bottom of the ship may be a measurement by a diver or may be a measurement using metrology equipment located at the reference point.

Second, the draft deformation may be temporarily installed on both sides of the ship under the slope test conditions, and the amount of kill deformation may be measured by measuring the draft of all points where the draft mark is constructed when measuring the slope test draft. The draft mark, which is temporarily constructed, must be constructed at as many points as possible to ensure the accuracy of the displacement calculation, and for example, it can be constructed at each station of the ship.

Third, the amount of kill deformation can be measured by measuring the upper deck or the hatch coaming surface under the inclined test conditions. That is, in the deformation of the ship, the kill deformation is represented by the deformation of the upper deck or the hatch coaming surface, and the deformation of the upper deck or the hatch coaming surface may be measured using a three-dimensional measuring instrument, and this may be regarded as the kill deformation amount. Here, in the case of the tank ship, the deformation amount of the upper deck may be measured, and in the case of the container ship, the deformation amount of the upper surface of the hatch coaming may be measured.

Looking at the method of measuring the amount of deformation of the upper deck or hatch coaming upper surface using the three-dimensional measuring instrument in detail as follows.

As shown in FIG. 4, the three-dimensional instrument 10 may be located on the deck of the vessel 1. For example, after measuring the laser L to the target 20, the 3D measuring instrument 10 measures the laser reflected by the target 20, and the position and reflection of the laser L irradiated. Using the difference in the position of the laser beam, the three-dimensional position of the target 20 is determined in consideration of the angle of the target 20 and the like. Thereby, the deformation amount of the upper surface of the ship 1 can be determined. At this time, the position 20 and the angle of the target 20 are determined within the visible range so that the 3D measuring device 10 can accommodate the laser beam reflected.

In FIG. 4, four targets 20 are installed on the upper deck or the hatch coaming surface, and three three-dimensional measuring units 10 are installed to measure the deformation amount of the upper deck or the hatch coaming surface, but the targets 20 and 3 are shown. The number and position of dimensional meters 10 can be selected from the position of those skilled in the art.

As described above, in the case of measuring the amount of deformation of a ship with a three-dimensional measuring instrument, a safe and easy measurement is possible as compared with the case of measuring the amount of deformation in a direct kill.

Next, the amount of drainage in the undeformed and deformed state of the ship is determined (S2).

As described above, the deformed state shape of the ship may be determined at the initial design stage of the ship, and the deformed state shape of the ship may be determined by measuring the kill amount of the ship. Therefore, the amount of drainage of the ship can be determined through computer simulation or numerical analysis of the ship shape thus determined. That is, by using the shape of the ship's undeformed and deformed state input on the computer, it is possible to obtain the ship's water drainage by the integral value through simulation or numerical analysis. The ship's drainage thus determined is then used to find the ship's modified draft and correction factor.

The modified draft of the vessel is determined (S3) by using the displacement amount of the undeformed state and the deformed state of the vessel determined by the above-described method. When the correction draft is determined, the correction coefficient can be obtained by dividing the correction amount for the correction draft from the initial draft by the deformation amount (S4).

For example, in the case where 500 mm of hogging occurs due to deformation of the ship, the correction draft determination method will be described in detail with reference to FIG. 3. FIG. 3 is a calculation table for determining correction draft and correction coefficients respectively when 500 mm and 350 mm hogging occurs, but hereinafter, the hogging will be described in detail only when 500 mm hogging occurs. The same can be applied to.

In FIG. 3, the values for each column include a draft, a repair area coefficient (Cw), a state of no deformation (a state in which hogging is '0'), and a discharge amount [Disp. 1 (Hogg. 0)], deformation state (with hogging '500 mm') displacement [Disp. 2 (Hogg. 500)], the amount of correction to be the correction draft at the initial draft [draft corr. (1)], the correction factor [Corr. (1) (hogging) 1-% and the hogging correction factor (1) (% )], Deformation state (with hogging '350mm') displacement [Disp. 3 (Hogg. 350)], the amount of correction to be the correction draft at the initial draft [draft corr. (2)], the correction factor [Corr. (2) (hogging) 1-% and the hogging correction factor (2) (% ), And the correction coefficient difference [diff (H500-H350)]. Here, the repair area coefficient Cw is a value determined according to the shape of the cross section in the width direction of the hull.

The draft in FIG. 3 is the draft at midship.

Draft corr (1) to be the corrected draft from the initial draft means the draft corrected amount that must be corrected in order to be a non-deformed displacement. For example, if the draft is 5.6, the steady state drainage is 41719.5 and the strained state drainage is 42526.8. Here, the correction amount [draft corr (1)] for the draft at which the strained state drain becomes the unchanged state drainage is '5.6 + draft corr (1)' is 0.090 = [(5.8-5.6) * (42526.8- 41719.5) / (43511.7-41719.5)].

In this way, it is possible to obtain a correction amount [draft corr (1)] to be a correction draft from the initial draft for each draft, which is used as a correction amount to correct the draft (draft). The correction draft can be obtained by adding the correction amount thus obtained to the initial draft.

Once the amount of correction to be the corrected draft is determined from the initial draft, the correction factor can be obtained by dividing this by the ship deformation. For example, as shown in FIG. 3, the correction amount [draft corr (1)] to be the correction draft from the initial draft can be obtained by dividing by the hogging amount 500 mm (= 0.5 m). Representatively, when the correction amount 0.090 when the draft is 5.6 is divided by the hogging amount 500 mm, it can be seen that the correction factor [Corr. (1) (hogging) 1-%] becomes 0.180 (0.090 / 0.5). The correction factor is obtained by using the correction factor [Corr. (1) (hogging) 1-%, 0.180 in the above example (hereinafter referred to as CF1)) obtained as described above or subtracting this value from 1 [Hogging correction Factor (1)]. (%)] (Hereinafter referred to as CF2).

Thus, the correction factor can be interpreted based on the following equation.

dcorr = dm + CF1 * deflection = dM-CF2 * deflection

(dcorr is the modified draft, dm is the midship hull, dM is the average draft of the bow and stern draft, and deflection is the deformation amount dM-dm)

Here, the correction coefficients CF1 and CF2 thus obtained do not vary greatly according to the deformation amount of the ship, and thus can be used regardless of the degree of deformation of the ship in obtaining the light weight of the ship. That is, as shown in FIG. 3, the same calculation is performed for the case where 350 mm hogging occurs, and the Hogging correction factor (2) (%) obtained at this time is compared with the case where 500 mm hogging occurs. It can be seen that there is almost no difference. That is, it can be seen that 'diff (H500-H300)' has an absolute value of 0 to 0.001.

Therefore, the calculation or calculation of the correction coefficients CF1 and CF2 obtained as described above can be used regardless of the degree of deformation of the ship, and thus can be widely used for calculating the light weight of the ship.

The calculation or calculation of the correction coefficients CF1 and CF2 may be performed on a computer, and may be performed on the same program as the calculation for calculating the deformed state displacement and the undeformed state displacement of the ship.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. You will understand that. For example, those skilled in the art can change the material, size, etc. of each component according to the application field, or combine or substitute the embodiments in a form that is not clearly disclosed in the embodiments of the present invention, this also It is within the scope of the invention. Therefore, the above-described embodiments are merely illustrative in all respects and should not be understood as limiting the present invention, and such modified embodiments should be included in the technical idea described in the claims of the present invention. .

1: Ships
10: 3D measuring instrument
20: target
L: laser

Claims (7)

delete Determining the deformation state of the ship,
Determining a deformation state shape of the ship in a state in which the ship is suspended;
Determining the drainage amount according to the deformation state shape and the deformation state shape for each draft of the ship,
Obtaining a corrected draft using the non-deformed shape and the drainage amount according to the deformed shape;
Obtaining a correction factor using the average draft of the bow and stern draft or the midship hull measured in the suspended draft and in the suspended state,
Obtaining the correction factor,
A value obtained by subtracting the corrected draft from the average draft is divided by the deformation of the vessel as a correction factor.
Method of Determination of Modification Factor for Estimation of Light Weight of Ship.
Determining the deformation state of the ship,
Determining a deformation state shape of the ship in a state in which the ship is suspended;
Determining the drainage amount according to the deformation state shape and the deformation state shape for each draft of the ship,
Obtaining a corrected draft using the non-deformed shape and the drainage amount according to the deformed shape;
Obtaining a correction factor using the average draft of the bow and stern draft or the midship hull measured in the suspended draft and in the suspended state,
Obtaining the correction factor,
A value obtained by subtracting the hull center draft from the corrected draft is divided by the deformation of the vessel as a correction factor.
Method of Determination of Modification Factor for Estimation of Light Weight of Ship.
The method according to claim 2 or 3,
The deformation amount is
The average draft is obtained by subtracting the hull central draft.
Method of Determination of Modification Factor for Estimation of Light Weight of Ship.
The method according to claim 2 or 3,
The deformation amount is
At least one of the deformation amount by the hogging (hogging) and sagging (sagging) of the vessel
Method of Determination of Modification Factor for Estimation of Light Weight of Ship.
The method according to claim 2 or 3,
Determining the deformation state shape of the vessel,
Determined by measuring the shape of the vessel with a three-dimensional measuring instrument.
Method of Determination of Modification Factor for Estimation of Light Weight of Ship.
The method according to claim 6,
The three-dimensional measuring instrument for measuring the upper deck or hatch coaming surface of the vessel
Method of Determination of Modification Factor for Estimation of Light Weight of Ship.

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