CII rating method based on fleet

Abstract

The invention relates to the technical field of ship operation optimization, in particular to a fleet-based CII rating method. Reading the technical information of each ship in the fleet, and obtaining the carrying information and calculation coefficient of a single ship; collecting a CII value, a total sailing distance and a sailing distance of a leg which can be deducted from CII calculation of the single ship after the single ship is corrected over the years; determining a CII reduction coefficient of the single ship by referring to a CII reduction coefficient guide rule and experience; calculating a CII value required by the single ship based on the obtained carrying capacity of the single ship and the CII reduction coefficient of the single ship; based on the total sailing distance of the single ship, the sailing distance of the leg which can be deducted from the CII calculation and the CII value required by the single ship, calculating a deduction correction coefficient of the single ship or the fleet and the corresponding actual discharge amount and various theoretical discharge amounts after the leg is removed; and comparing the actual discharge amount of the fleet with various theoretical discharge amounts so as to obtain the CII rating of the fleet, thereby solving the problem that the CII rating cannot be carried out on the fleet by the current CII rating method.

Description

Technical Field

[0001] The present invention relates to the technical field of ship operation optimization, and particularly relates to a CII rating method based on a fleet. Background Art

[0002] CII (Operational Carbon Intensity Indicator), namely the ship operation carbon intensity indicator, is an indicator to measure the ship operation carbon intensity, specifically referring to the measurement of the average CO2 emissions per unit of shipping workload of the ship. The existing CII rating methods are only applicable to single ships and cannot conduct CII rating for the entire fleet. In addition, there are certain defects in the existing single-ship CII rating methods, and the CII rating results of some single ships are unreasonable. Shipping companies cannot scientifically and reasonably evaluate the CII level of ships and accurately understand the actual CII level of ships.

[0003] Currently, the single-ship CII rating method cannot evaluate the CII level of the entire fleet, nor can it accurately evaluate the CII level of a single ship, resulting in poor ratings for some ships with excellent propulsion performance. Shipping companies cannot evaluate the CII level of the fleet and understand the overall carbon intensity level of the fleet. Summary of the Invention

[0004] The present invention solves the problem that the existing CII rating methods cannot conduct CII rating for the fleet, and provides a CII rating method based on the fleet to conduct CII rating for the shipping company's fleet.

[0005] The technical solution claimed by the present invention is as follows:

[0006] A CII rating method based on a fleet, comprising the following steps;

[0007] S1: Read the technical information of each ship in the fleet and obtain the key features in the technical information; the key features include the carrying capacity and the calculation coefficient; each ship in the fleet is called a single ship;

[0008] S2: Collect the CII value reached by the single ship after calendar year correction, the total navigation distance, and the navigation distance of the section that can be deducted from the CII calculation; and determine the CII reduction coefficient of the single ship with reference to the CII reduction coefficient guidelines and experience;

[0009] S3: Calculate the required CII value of the single ship based on the carrying capacity of the single ship obtained in S1 and the CII reduction coefficient of the single ship calculated in S2;

[0010] S4: Calculate the actual emissions and various theoretical emissions corresponding to the single ship or the fleet after deducting the correction coefficient and section exemption based on the total navigation distance of the single ship obtained in S2, the navigation distance of the section that can be deducted from the CII calculation, and the required CII value of the single ship calculated in S3;

[0011] S5: Compare the actual emissions of the fleet with various theoretical emissions, and then obtain the CII rating of the fleet.

[0012] Preferably, the key features in S1 also include the ship type; different ship types are included in the fleet; the calculation coefficients include: the correction coefficient of the carrying capacity of ice-strengthened ships, the coefficients of ice-class ships with IASuper and IA ice classes, the correction coefficient of cubic capacity, and the coefficient of ship-specific voluntary structural strengthening.

[0013] Preferably, for the CII reduction coefficient of a single ship in S2, it is determined with reference to the CII reduction coefficient guidelines in 2026 and before 2026, and will increase by 2% annually according to experience after 2026.

[0014] Preferably, the calculation formula for the CII value required for a single ship in S3 is:

[0015] CII r = a·Capacity -c ·(1 - Z)

[0016] In the formula: CIIr represents the CII value required for a single ship; a and c are constants determined according to the ship type; Capacity represents the carrying capacity. For bulk carriers, tankers, container ships, gas carriers, LNG carriers, general cargo ships, refrigerated cargo ships, and combination carriers, the summer deadweight tonnage is used as the carrying capacity; for cruise ships, roll-on / roll-off cargo ships, roll-on / roll-off passenger ships, the gross tonnage is used as the carrying capacity; Z represents the CII reduction coefficient of a single ship.

[0017] Preferably, the actual emissions and various theoretical emissions in S5 include: the actual CO2 emissions of a single ship / fleet, the theoretical CO2 emissions corresponding to reaching the excellent boundary, the theoretical CO2 emissions corresponding to reaching the lower boundary, the theoretical CO2 emissions corresponding to reaching the required CII, the theoretical CO2 emissions corresponding to reaching the higher boundary, and the theoretical CO2 emissions corresponding to reaching the inappropriate boundary.

[0018] Preferably, the calculation formulas for the actual emissions and various theoretical emissions in S5 are as follows:

[0019] S = ∑ n S n = ∑ n f i,n ·f m,n ·f c,n ·f iVSE,n ·Capacity n ·(D t,n - D x,n )·superiorboundary n

[0020] L = ∑ n L n = ∑ n f i,n · f m,n · f c,n · f iVSE,n · Capacity n · (D t,n - D x,n ) · lowerboundary n

[0021] RE = ∑ n RE n = ∑ n f i,n · f m,n · f c,n · f iVSE,n · Capacity n · (D t,n - D x,n ) · CII r,n

[0022] U = Σ n U n = Σ n f i,n · f m,n · f c,n · f iVSE,n · Capacity n · (D t,n - D x,n ) · upperboundary n

[0023] I = ∑ n I n = Σ n f i,n · f m,n · f c,n · f iVSE,n · Capacity n · (D t,n - D x,n ) · inferiorboundary n

[0024] T = Σ n T n

[0025] T n = f i,n · f m,n · f c,n · f iVSE,n · Capacity n·(D t,n -D x,n )·CII a,n

[0026] superior boundary n =exp(d1)·CII r,n

[0027] lower boundary n =exp(d2)·CII r,n

[0028] upper boundary n =exp(d3)·CII r,n

[0029] inferior boundary n =exp(d4)·CII r,n

[0030] In the formula: n represents the number of a single ship in the fleet; T n , T respectively represent the actual CO2 emissions of the single ship numbered n and the fleet; S n , S respectively represent the theoretical CO2 emissions corresponding to the excellent boundary reached by the single ship numbered n and the fleet; L n , L respectively represent the theoretical CO2 emissions corresponding to the lower boundary reached by the single ship numbered n and the fleet; RE n , RE respectively represent the theoretical CO2 emissions for the single ship numbered n and the fleet to reach the required CII, U n , U respectively represent the theoretical CO2 emissions corresponding to the upper boundary reached by the single ship numbered n and the fleet, I n , I respectively represent the theoretical CO2 emissions corresponding to the inappropriate boundary reached by the single ship numbered n and the fleet; CII r，n represents the CII value required for the single ship numbered n; CII a，n represents the CII value reached after correction for the single ship numbered n; Capacity n is the carrying capacity of the single ship numbered n; D t,n represents the total corrected navigation distance of the single ship numbered n in the calendar year; D x,n represents the deductible navigation distance of the single ship numbered n in the calendar year after correction; f i,n represents the correction coefficient of the carrying capacity of the single ship numbered n for an ice-strengthened ship; f m,n represents the coefficient of the single ship numbered n for an ice-class ship with IA Super and IA ice classes; f c,n represents the correction coefficient of the cubic volume of the single ship numbered n; f iVSE,nDenote the specific voluntary structural strengthening coefficient of a single ship numbered n, which is only applicable to self-unloading bulk carriers; d1, d2, d3, and d4 respectively denote the unit vectors corresponding to the excellent boundary, lower boundary, upper boundary, and unqualified boundary.

[0031] Preferably, the CII rating of the fleet is divided into five grades: A, B, C, D, and E.

[0032] Preferably, if T <= S, the ratings of all ships in the fleet are A; if S < T <= L, the ratings of all ships in the fleet are B; if L < T <= U, the ratings of all ships in the fleet are C; if U < T <= I, the ratings of all ships in the fleet are D; if I < T, the ratings of all ships in the fleet are E.

[0033] Beneficial effects:

[0034] The present invention provides a method for CII rating based on a fleet, which reads the technical information of each ship in the fleet to obtain the carrying information of a single ship; collects the CII value achieved after the annual calendar correction of a single ship, the total navigation distance, and the navigation distance of the voyage section that can be deducted from the CII calculation; and determines the CII reduction coefficient of a single ship with reference to the CII reduction coefficient guidelines and experience; calculates the required CII value of a single ship based on the obtained carrying capacity of a single ship and the CII reduction coefficient of a single ship; calculates the actual emissions and various theoretical emissions corresponding to a single ship or a fleet after deducting the correction coefficient and voyage exemption based on the total navigation distance of a single ship, the navigation distance of the voyage section that can be deducted from the CII calculation, and the required CII value of a single ship; compares the actual emissions of the fleet with the magnitudes of various theoretical emissions, and thus obtains the CII rating of the fleet, solving the problem that the current CII rating method cannot conduct CII rating on the fleet.

[0035] The implementation of the CII rating based on the fleet in the present invention will help relevant stakeholders understand the current situation of the overall CII rating of the fleet. Generally, it will reduce the unreasonableness of the defects of the existing single-ship CII rating method, facilitating shipping companies to carry out targeted rating improvement measures scientifically and reasonably. Conducting CII rating based on the fleet will encourage shipping companies to concentrate limited funds on investing in some innovative emission reduction technologies for ships with better ship energy efficiency, enabling these emission reduction technologies to have a longer operating time and achieve more greenhouse gas emissions reduction; enabling shipping companies to publicize the CII level of the fleet externally, prompting shipping companies to reduce greenhouse gas emissions, and promoting the shipping industry to transform towards green and low-carbon. Description of the Drawings

[0036] Figure 1 It is a schematic flowchart of the method for CII rating based on the fleet in the embodiment of the present invention. Detailed Embodiment

[0037] The present invention will be described in detail below with reference to the drawings.

[0038] The present invention provides a CII rating method based on a fleet, as Figure 1 shown, which includes the following steps:

[0039] S1: Read the technical information of each ship in the fleet to obtain the key features in the technical information; the key features include the carrying capacity and the calculation coefficient; each ship in the fleet is called a single ship; in a specific embodiment of the present invention, the technical information of the single ship in the fleet is read to obtain the ship type, the calculation coefficient, and the carrying capacity. The following takes 6 ships with the ship types of container ships and liquid cargo ships in 2023 as an example for illustration. The ship numbers are 1-6 (corresponding to Ship 1 - Ship 6 respectively). Ship 1 is a container ship with a carrying capacity of 25,000 tons; Ship 2 is a container ship with a carrying capacity of 70,000 tons; Ship 3 is a container ship with a carrying capacity of 125,000 tons; Ship 4 is a container ship with a carrying capacity of 155,000; Ship 5 is a liquid cargo ship with a carrying capacity of 50,000 tons; Ship 6 is a liquid cargo ship with a carrying capacity of 76,000 tons; f i,n represents the carrying capacity correction coefficient of the single ship ice class strengthened ship numbered n; f m,n represents the coefficient of the ice class ship with IA Super and IA ice class of the single ship numbered n; f c,n represents the cubic volume correction coefficient of the single ship numbered n; f iVSE,n represents the specific voluntary structural strengthening coefficient of the single ship numbered n, which is only applicable to self-unloading bulk carriers; n represents the number of the single ship in the fleet; for Ships 1 - 6, the calculation coefficients f i,n 、f m,n 、f c,n 、f iVSE,n are selected, and in f c,5 = 1.03 (the cubic volume correction coefficient of Ship 5 is), and the rest are all 1.

[0040] S2: Collect the CII values, total navigation distances, and navigation distances of the segments that can be deducted from the CII calculation reached by a single ship after correction in the calendar year; and determine the CII reduction factor of the single ship with reference to the CII reduction factor guidelines and experience. In a specific embodiment of the present invention, in 2023, the CII value reached by Ship 1 after correction is 9.2 gCO2 / (dwt·nmile), and the total navigation distance is 60,000 nautical miles; in 2023, the CII value reached by Ship 2 after correction is 8 gCO2 / (dwt·nmile), and the total navigation distance is 85,000 nautical miles; in 2023, the CII value reached by Ship 3 after correction is 5.8 gCO2 / (dwt·nmile), and the total navigation distance is 95,000 nautical miles; in 2023, the CII value reached by Ship 4 after correction is 6.2 gCO2 / (dwt·nmile), and the total navigation distance is 97,000 nautical miles; in 2023, the CII value reached by Ship 5 after correction is 4.7 gCO2 / (dwt·nmile), and the total navigation distance is 67,000 nautical miles; for the above Ships 1 - 5, the navigation distance of the segments that can be deducted from the CII calculation is 0; in 2023, the CII value reached by Ship 6 after correction is 4.8 gCO2 / (dwt·nmile), and the total navigation distance is 65,000 nautical miles, and the navigation distance of the segments deducted from the CII calculation is 1,000 nautical miles.

[0041] Determine the CII reduction factor for each year of a single ship starting from 2023 with reference to the CII reduction factor guidelines and experience as shown in Table 1.

[0042] Table 1. Reduction Factors for Each Year of a Single Ship after 2023

[0043] Year Reduction Coefficient Z 2023 5％ 2024 7％ 2025 9％ 2026 11％ In 2027 and after Increase by 2% annually

[0044] S3: Calculate the CII value required for a single ship based on the carrying capacity of the single ship obtained in S1 and the CII reduction factor of the single ship calculated in S2. In a specific embodiment of the present invention, the calculation formula for the CII value required for a single ship is:

[0045] CII r = a·Capacity -c ·(1 - Z)

[0046] In the formula: CIIr represents the CII value required for a single ship; a and c are constants determined according to the ship type; Capacity represents the carrying capacity. For bulk carriers, liquid cargo ships, container ships, gas carriers, LNG carriers, general cargo ships, refrigerated cargo ships, and multi-purpose ships, the summer deadweight tonnage is used as the carrying capacity; for cruise ships, ro-ro cargo ships, ro-ro passenger ships, the gross tonnage is used as the carrying capacity; Z represents the CII reduction factor of the single ship. The values of the carrying capacity Capacity, a, and c corresponding to different ship types are shown in Table 2.

[0047] Table 2. Values of the carrying capacity Capacity, a, and c corresponding to different ship types

[0048]

[0049]

[0050] S4: Based on S2, obtain the total single - ship navigation distance and the navigation distance of the segments that can be deducted from the CII calculation, and calculate the actual emissions and various theoretical emissions corresponding to the single ship or fleet after deducting the correction factor and segment exemption using S3; the actual emissions and various theoretical emissions include: the actual CO2 emissions of the single ship / fleet, the theoretical CO2 emissions corresponding to reaching the excellent boundary, the theoretical CO2 emissions corresponding to reaching the lower boundary, the theoretical CO2 emissions corresponding to reaching the required CII, the theoretical CO2 emissions corresponding to reaching the higher boundary, and the theoretical CO2 emissions corresponding to reaching the inappropriate boundary. The calculation formulas are as follows:

[0051] S = ∑ n S n = ∑ n f i,n ·f m,n ·f c,n ·f iVSE,n ·Capacity n ·(D t,n - D x,n )·superiorboundary n

[0052] L = ∑ n L n = ∑ n f i,n ·f m,n ·f c,n ·f iVSE,n ·Capacity n ·(D t,n - D x,n )·lowerboundary n

[0053] RE = ∑ n RE n = ∑ n f i,n ·f m,n ·f c,n ·f iVSE,n ·Capacity n ·(D t,n - D x,n )·CII r,n

[0054] U = ∑ n U n = ∑ n f i,n ·f m,n ·f c,n ·f iVSE,n ·Capacity n ·(D t,n - D x,n )·upper boundary n

[0055] I = ∑ n I n = ∑ n f i,n ·f m,n ·f c,n ·f iVSE,n ·Capacity n ·(D t,n - D x,n )·inferior boundary n

[0056] T = Σ n T n

[0057] T n = f i,n ·f m,n ·f c,n ·f iVSE,n ·Capacity n ·(D t,n - D x,n )·CII a,n

[0058] superior boundary n = exp(d1)·CII r,n

[0059] lower boundary n = exp(d2)·CII r,n

[0060] upper boundary n = exp(d3)·CII r,n

[0061] inferior boundary n = exp(d4)·CII r,n

[0062] In the formula: n represents the number of a single ship in the fleet. The maximum value of n is the number of single ships in the fleet, and the minimum value is 1. All single ships in the fleet are numbered from 1 to n; T n and T respectively represent the actual CO2 emissions of the single ship numbered n and the fleet; S n and S respectively represent the theoretical CO2 emissions corresponding to the excellent boundary of the single ship numbered n and the fleet; L n and L respectively represent the theoretical CO2 emissions corresponding to the lower boundary of the single ship numbered n and the fleet; RE n and RE respectively represent the theoretical CO2 emissions for the single ship numbered n and the fleet to achieve the required CII, U n and U respectively represent the theoretical CO2 emissions corresponding to the higher boundary of the single ship numbered n and the fleet; I n and I respectively represent the theoretical CO2 emissions corresponding to the inappropriate boundary of the single ship numbered n and the fleet; CII r，n represents the CII value required for the single ship numbered n; Capacity n is the carrying capacity of the single ship numbered n; D t,n represents the total corrected voyage distance of the single ship numbered n in the calendar year; D x,n represents the deductible voyage distance of the single ship numbered n in the calendar year after correction; f i,n represents the correction coefficient of the carrying capacity of the ice-strengthened ship of the single ship numbered n; f m,n represents the coefficient of the ice-class ship with IA Super and IA ice classes of the single ship numbered n; f c,n represents the correction coefficient of the cubic volume of the single ship numbered n; f iVSE,n represents the specific voluntary structural strengthening coefficient of the single ship numbered n, which is only applicable to self-unloading bulk carriers; d1, d2, d3, and d4 respectively represent the unit vectors corresponding to the excellent boundary, lower boundary, higher boundary, and unqualified boundary (Table 3).

[0063] Table 3. Values of Capacity, d1, d2, d3, and d4 corresponding to different ship types

[0064]

[0065] Based on the above formula for calculation, the actual emissions and various theoretical emissions corresponding to Ships 1 - 6 mentioned in S1 and the fleet composed of Ships 1 - 6 are as follows:

[0066] Ship 1: S1 = 17462979935 gCO2, L1 = 19777350770 gCO2, RE1 = 21039734862 gCO2, U1 = 22512516302 gCO2, I1 = 25037284486 gCO2, T1 = 13800000000 gCO2.

[0067] Ship 2: S2 = 41868151246 gCO2, L2 = 47416942375 gCO2, RE2 = 50443555718 gCO2, U2 = 53974604618 gCO2, I2 = 60027831304 gCO2, T2 = 47600000000 gCO2.

[0068] Ship 3: S3 = 62930963659 gCO2, L3 = 71271211855 gCO2, RE3 = 75820438143 gCO2, U3 = 81127868813 gCO2, I3 = 90226321391 gCO2, T3 = 68875000000 gCO2.

[0069] Ship 4: S4 = 71721768907 gCO2, L4 = 81227063581 gCO2, RE4 = 86411769767 gCO2, U4 = 92460593651 gCO2, I4 = 102830006023 gCO2, T4 = 93217000000 gCO2.

[0070] Ship 5: S5 = 19184869571 gCO2, L5 = 21758449635 gCO2, RE5 = 23396182403 gCO2, U5 = 25267876995 gCO2, I5 = 29947113476 gCO2, T5 = 16217350000 gCO2.

[0071] Ship 6: S6 = 20948155876 gCO2, L6 = 23758274347 gCO2, RE6 = 25546531556 gCO2, U6 = 27590254081 gCO2, I6 = 32699560392 gCO2, T6 = 23347200000 gCO2.

[0072] Fleet: S = 234116889193 gCO2, L = 265209292563 gCO2, RE = 282658212449 gCO2, U = 302933714460 gCO2, I = 340768117071 gCO2, T = 263056550000 gCO2.

[0073] S5: Compare the actual emissions of the fleet with various theoretical emissions, and then obtain the CII rating of the fleet; in a specific embodiment of the present invention, the CII rating of the fleet is divided into five grades: A, B, C, D, and E; if T <= S, the ratings of all ships in the fleet are A; if S < T <= L, the ratings of all ships in the fleet are B; if L < T <= U, the ratings of all ships in the fleet are C; if U < T <= I, the ratings of all ships in the fleet are D; if I < T, the ratings of all ships in the fleet are E. For the fleet in S4, S < T <= L, therefore, the ratings of all ships in the fleet composed of Ship 1 - Ship 6 are B.

[0074] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A fleet-based CII rating method, characterized in that, It includes the following steps; S1: Read the technical information of each ship in the fleet and obtain the key features in the technical information; the key features include the carrying capacity and the calculation coefficient; each ship in the fleet is called a single ship; S2: Collect the CII value reached after the single ship's calendar year is corrected, the total navigation distance, and the navigation distance of the voyage section that can be deducted from the CII calculation; and determine the CII reduction coefficient of the single ship with reference to the CII reduction coefficient guidelines and experience; S3: Calculate the CII value required for the single ship based on the carrying capacity of the single ship obtained in S1 and the CII reduction coefficient of the single ship calculated in S2; S4: Calculate the actual emissions and various theoretical emissions corresponding to the single ship or the fleet after deducting the correction coefficient and voyage exemption based on the total navigation distance of the single ship obtained in S2, the navigation distance of the voyage section that can be deducted from the CII calculation, and the CII value required for the single ship calculated in S3; S5: Compare the actual emissions of the fleet with the magnitudes of various theoretical emissions, and then obtain the CII rating of the fleet.

2. The fleet-based CII rating method according to claim 1, wherein The key features in S1 also include the ship type; different ship types are included in the fleet; the calculation coefficients include: the carrying capacity correction coefficient for ice-strengthened ships, the coefficients for ice-class ships with IA Super and IA ice classes, the cubic volume correction coefficient, and the ship-specific voluntary structural strengthening coefficient.

3. The fleet-based CII rating method according to claim 2, wherein For the CII reduction coefficient of the single ship in S2, it is determined with reference to the CII reduction coefficient guidelines in 2026 and before 2026, and will increase by 2% annually according to experience after 2026.

4. The fleet-based CII rating method according to claim 3, wherein The calculation formula for the CII value required for the single ship in S3 is as follows: CII r = a · Capacity -c · (1 - Z) In the formula: CIIr represents the CII value required for the single ship; a and c are constants determined according to the ship type; Capacity represents the carrying capacity. For bulk carriers, liquid cargo ships, container ships, gas carriers, LNG carriers, general cargo ships, refrigerated cargo ships, and multi-purpose ships, the summer deadweight tonnage is used as the carrying capacity; for cruise ships, ro-ro cargo ships, ro-ro passenger ships, the gross tonnage is used as the carrying capacity; Z represents the CII reduction coefficient of the single ship.

5. The fleet-based CII rating method according to claim 4, wherein The actual emissions and various theoretical emissions in S5 include: the actual CO2 emissions of the single ship / fleet, the theoretical CO2 emissions corresponding to reaching the excellent boundary, the theoretical CO2 emissions corresponding to reaching the lower boundary, the theoretical CO2 emissions corresponding to reaching the required CII, the theoretical CO2 emissions corresponding to reaching the higher boundary, and the theoretical CO2 emissions corresponding to reaching the inappropriate boundary.

6. The fleet-based CII rating method according to claim 5, wherein The calculation formulas for the actual emissions and various theoretical emissions in S5 are as follows: S = ∑ n S n = ∑ n f i,n · f m,n · f c,n · f iVSE,n · Capacity n · (D t,n - D x,n ) · superior boundary n L = ∑ n L n = ∑ n f i,n · f m,n · f c,n · f iVSE,n · Capacity n · (D t,n - D x,n ) · lower boundary n RE = ∑ n RE n = ∑ n f i,n · f m,n · f c,n · f iVSE,n · Capacity n · (D t,n - D x,n )· CII r,n U = ∑ n U n = ∑ n f i,n ·f m,n ·f c,n ·f iVSE,n ·Capacity n ·(D t,n - D x,n )·upper boundary n I = ∑ n I n = ∑ n f i,n · f m,n · f c,n · f iVSE,n · Capacity n · (D t,n - D x,n ) · inferior boundary n T = ∑ n T n T n = f i,n · f m,n · f c,n · f iVSE,n · Capacity n · (D t,n - D x,n ) · CII a,n superior boundary n = exp(d1)·CII r,n lower boundary n = exp(d2)·CII r,n upper boundary n = exp(d3)·CII r,n inferior boundary n = exp(d4)·CII r,n Where: n represents the number of a single ship in the fleet; T n , T respectively represent the actual CO2 emissions of the single ship numbered n and the fleet; S n , S respectively represent the theoretical CO2 emissions corresponding to the excellent boundary of the single ship numbered n and the fleet; L n , L respectively represent the theoretical CO2 emissions corresponding to the lower boundary of the single ship numbered n and the fleet; RE n , RE respectively represent the theoretical CO2 emissions for the single ship numbered n and the fleet to reach the required CII, U n , U respectively represent the theoretical CO2 emissions corresponding to the higher boundary of the single ship numbered n and the fleet; I n , I respectively represent the theoretical CO2 emissions corresponding to the inappropriate boundary of the single ship numbered n and the fleet; CII r，n represents the CII value required for the single ship numbered n; CII a，n represents the CII value reached after correction for the single ship numbered n; Capacity n is the carrying capacity of the single ship numbered n; D t,n represents the total corrected navigation distance of the single ship numbered n in the calendar year; D x,n represents the deductible navigation distance of the single ship numbered n after correction in the calendar year; f i,n represents the correction coefficient of the carrying capacity of the single ship numbered n with ice class strengthening; f m,n represents the coefficient of the ice class ship with IA Super and IA ice class for the single ship numbered n; f c,n represents the correction coefficient of the cubic volume of the single ship numbered n; f iVSE,n represents the specific voluntary structural strengthening coefficient of the single ship numbered n, which is only applicable to self-unloading bulk carriers; d1, d2, d3, d4 respectively represent the unit vectors corresponding to the excellent boundary, lower boundary, higher boundary and unqualified boundary.

7. The fleet-based CII rating method according to claim 6, wherein The CII rating of the fleet is divided into five grades: A, B, C, D, and E.

8. The fleet-based CII rating method according to claim 7, wherein If T <= S, all ships in the fleet are rated A; if S < T <= L, all ships in the fleet are rated B; if L < T <= U, all ships in the fleet are rated C; If U < T <= I, all ships in the fleet are rated D; if I < T, all ships in the fleet are rated E.

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