A Feasibility Review for an Uneven Baseline Basis Minimal Ballast Ship

Article information

J. Ocean Eng. Technol. 2020;34(1):1-12
Publication date (electronic) : 2020 February 26
doi : https://doi.org/10.26748/KSOE.2019.111
1Principal Researcher, Advanced Ship Research Division, Korea Research Institute of Ships and Ocean Engineering (KRISO), Daejeon, Korea
2Senior Researcher, Autonomous Ship Research Department, Korea Research Institute of Ships and Ocean Engineering (KRISO), Daejeon, Korea
3Senior Director, Advanced Ship Research Division, Korea Research Institute of Ships and Ocean Engineering (KRISO), Daejeon, Korea
Corresponding author Hee Jin Kang: +82-42-866-3417, hjkang@kriso.re.kr

It is noted that this paper is revised edition based on proceedings of IMAM 2017 in Lisbon.

Received 2019 December 16; Revised 2020 February 13; Accepted 2020 February 14.

Abstract

Although there are many kinds of advanced ballast water management systems, pioneering studies for ballast-water free ship and minimal ballast water ship concepts are in progress. In this study, the existing alternatives of ballast water are reviewed and a new design concept is studied on the basis of the existing bulk carrier hull form. To develop a new design alternative which has minimal ballast for ballast water discharge free operation, the new concept should have technical feasibilities that are related to the role of the ballast water, berth access, loading constraints, etc. For this purpose, a simplified systems engineering basis design approach is adopted using a business model as the system analysis and control tool. To check the performance feasibility of the new concept, ship resistance performance is reviewed based on a model scale ship resistance performance analysis.

1. Introduction

Because the measures from the Ballast water management (BWM) convention are being enacted in order to reduce the environmental damage caused by the global movement of marine life in the ballast water of ships (Albert et al., 2013), the negative effect of treated ballast water on the marine environment is another urgent issue (Werschkun et al., 2014). Notably, research on non/minimal ballast water vessels is actively underway in response to the D-1 or D-2 discharge standards of the convention. When considering the role of ballast water, as shown in Table 1, the ballast water contributes to the ship’s stability via proper maintenance of the draft and the center of gravity of a ship during voyage. Another aim of the ballast water is to maintain the appropriate immersion depth of the propeller for propulsion efficiency. Ballast water is also used to adjust the trim and heel of a ship. The bending moment and shear force can also be adjusted by the ballast water.

Roles of the ballast water in a ship (Isbester, 2010)

Depending on the ship types and routes, generally, 30% to 40% of the deadweight tonnage (DWT) is used as ballast water (Kerr, 1994). Many pioneering studies have been conducted to meet the D-1 or D-2 discharge standards of the BWM convention without needing to discharge the environmentally harmful ballast water. Table 2 shows alternatives for the BWM methods (GEF, U. and IMO, G.P., 2011).

Alternatives for the BWM methods [derived and edited from GEF, U. and IMO, G. P. 2011]

Among the various alternatives, in the case of ‘no or minimal discharge’ alternatives, the minimal ballast water ship (MIBS) and non-ballast water ship (NOBS) (Shingo, 2014) of a ‘storm ballast’ are considered to be practically applicable alternatives. Though there are some constraints for berthing and loading, in 2018, a NOBS concept basis ballast water-free ‘7,500 cubic meter liquefied natural gas (LNG) bunkering vessel’ was launched for commercial purposes (https://pulsenews.co.kr). For the ‘continuous flow’ type alternatives, ‘The Variable Buoyancy Ship Concept’ of ‘longitudinal trunks’ is remarkable. For the trim and heel control, the concept has been shown to adequately control the trim and draft (Parsons and Kotinis, 2011a; Parsons and Kotinis, 2011b). In this study, a new design concept for ‘no or minimal discharge’ alternatives is studied while considering the ship’s size and operational conditions.

2. Feasibility Study

To design a new minimal ballast vessel, a ship must be designed that has the functions of ballast water without or with the minimum use of ballast. The perspectives of performance, ship stability, resistance, trim and heel controllability, berth access and loading constraints should be considered. Technical complexity and cost related matters are also considered to ensure technical and economic feasibility.

To compensate for the existing BWM alternatives’ penalties, an appropriate approach and design process are required. In a systems engineering process, it is essential to identify, validate, and verify the various constraints of shipbuilding and operation in the design phase for the development of minimal ballast water vessel. Generally, the systems engineering basis design process involves a “system analysis and control tool”, which allows for the effective management of various design entities from various viewpoints, including technical and economic feasibility (Leonard, 1999; Kang et al., 2016). In this study, the business model was used as a system analysis and control tool, which was suggested by Kang et al. (2016). The business model consists of six elements: the design of a new concept for a minimal ballast vessel (Task); the required value of the enhanced berth access and loading capability compared to the existing ‘MIBS’ (Value); the expected revenue of the designed concept, such as a decrease in the ecosystem disturbance (meeting D-2) and the reasonable hull build cost (Revenue); the available and considered infrastructure, such as port facilities, ships in operation, rules and regulations, ship yards (Infra); the channels to enable the design concepts, such as technical and economic feasibilities (Channel); and the stakeholders of the task, including ship owners, ship builders, port authorities, classification societies, and fishing industries (Stakeholder). The factors considered in this study are shown in Table 3.

Business model for a new non / minimal ballast ship design

By adopting a business model for the systems analysis and a control tool for the design process, the ISO/IEC 15288-based ‘Vee’ design process was adopted and modified, as shown in Fig. 1. In the early phase of the design process, the measure of effectiveness (MOE), key performance parameters (KPPs), measure of performance (MOP) and technical performance measures (TPMs) should be identified in order to validate and verify the feasibility of the design results in the early phase of the design process. During the design process, all the design aspects should be analyzed and determined within the boundaries of the defined business model.

Fig. 1

Design process for a new minimal ballast ship design [derived and edited from (Kang et al., 2016)]

2.1 Requirement analysis

To achieve this goal, eight requirements were derived, as shown in Table 4. R1 to R7 are the general requirements for a non/minimal ballast water ship. The new design should meet the requirements at the same level as the previous alternatives. R8 is the requirements to overcome the existing difficulties of a ‘storm ballast’ of the ‘no or minimal discharge’ alternatives.

Redefined requirements for the new non/minimal ballast ship design

R1 is a requirement related to the stability of a ship. When changing the existing hull form, such as the MIBS, it is difficult to achieve the same stability as that of the existing ship. In such cases, the placement of the keel or stabilizer should be reviewed in terms of the dynamic behavior, propulsion power of the ship, and cost. R2 is a requirement for the trim and heel control, considering the weight distribution of cargo. R3 stipulates the immersion depth required for securing the self-propulsion capability of a ship. R4 is a requirement related to the operation cost of the ship. R5 states the condition for bow slamming reduction, which should be considered together with R3 to ensure the proper immersion depth of the bow. R6 and R7 are requirements for managing the load applied to the ship according to the cargo weight distribution and the arrangement of the ballast of the ship. R8 requires that the designed concept should be able to utilize the existing port facilities. From the results of the analysis of the requirements, the TPMs are generated and shown in Table 5. The TPM is generated from each essential requirement for a minimal ballast ship, and the MOP is measured after all TPMs are satisfied. Then, the MOE / KPP can be evaluated as a considerable design result.

Criteria, thresholds and indicators for TPMs

2.2 Functional analysis and allocation

Each requirement should be functionalized for the new minimal ballast ship design. To functionalize the requirements R1–R5 in Table 4, technologies pertaining to fluid performance are required. R6 and R7 are the requirements related to the structural strength, and R8 requires the ship be able to be adapted to existing harbor facilities. The functions to accommodate each requirement are listed in Table 6, including all the identified requirements.

Function list for new non/minimal ballast ship design

2.3 Synthesis

In the synthesis process, the design alternatives shall be generated to implement the functions in Table 6 within the boundaries of the business model. To implement F1 and F4, any requirements for new rules and regulations should be minimized. In addition, the existing rules and regulations for ship stability and structural strength must be satisfied. For F2, a minimum level of the propeller immersion depth and bow draft must be achieved. For F3, any type of external attachment should be avoided to ensure the appropriate ship resistance performance. For F4 and F5, changes in the draft, beam, and bilge radius of the existing ship should be limited to ensure the berth access and usability of cargo loading facilities. The adjustment of the baselines of the bow and stern of a ship can be used to meet the functional requirements. However, when considering the required couplings and machinery systems among the bow, stern, and cargo hold parts of the ship for adjusting the baseline, the design concept shown in Fig. 2 does not meet the ‘revenue’ of the business model.

Fig. 2

An initial concept of the adjustable bow, stern and cargo hold baselines for non/minimal ballast operation

Since it is practically impossible for an adjustable hull form to meet the requirements of Table 4 and the business model of Table 3, to build a reasonable design alternative for the functions in Table 6, a fixed type uneven baseline hull form (modified) has been generated on the basis of an existing 176K bulk carrier hull form (original). Fig. 3 shows the body plan of an uneven baseline minimal ballast bulk carrier.

Fig. 3

Body plan, modified (left side) and original (right side) hull form

From the Fig. 3, the suggested ‘modified’ hull form has uneven baselines of the bow, stern, and cargo holds. These differences should be addressed because an uneven baseline can affect the ship’s resistance performance. In addition, an uneven baseline interferes with the fluid flow and affects the seakeeping ability for F1. Furthermore, measures should be taken to secure the longitudinal strength under repetitive hogging and sagging conditions. To reduce the adverse effects of the shear force and bending moment on the structural strength of the hull, the heel trim must be carefully weighed and controlled during the cargo loading process. For F1 and F4, a center-line bottom keel-based structural reinforcement can be used. While a fin-stabilizer for F1 has no effect on the normal concept of the static stability of a ship, it has a positive effect on the dynamic stability. Since the fin is usually not considered for a large ship, the cost effectiveness and possible capacity of the fin should be considered before implementation. To obtain the proper immersion depth of the propeller of the designed ship, a reduction of the propeller diameter can be considered by changing from a single-screw to twin-screw propulsion with an uneven baseline. In addition, for non-ballast exchange operation in certain loading conditions, a permanent ballast system will be required for F2 and F5. In this case, the operation of the permanent ballast should take the water depth and loading condition control ability of the port into account. The design should also consider the amount of required permanent ballasts for securing the appropriate immersion depth and a safe return voyage with empty cargo holds. By increasing the baseline of the cargo holds, the wetted surface area is decreased slightly, which can contribute to the ship’s resistance performance. However, since the uneven baseline may have a negative effect on the ship resistance performance, the feasibility of design alternatives for F3 should be carefully examined. For F4, in the hull form modification process the applicability of the hull form to the existing rules and regulations is considered.

The provisional specifications of the designed ship are described in Table 7. From the hull form modification of the existing 176K bulk carrier, the wetted surface is reduced by approximately 4.4% compared to those of the original hull form under full loaded conditions. Under ballasting conditions, the required fixed ballast was estimated at approximately 42,000 t for a 7.5 m TA.

Initial dimensions of the designed ship

The synthesis results of reviewing the technical alternatives for the required functions are summarized in Table 8. The conceptually designed ship was reconfigured from the existing 176K bulk carrier. The tanks for the ballast are minimized and the auxiliaries and superstructure have been relocated for the initial trim and heel conditions. For S1, the uneven baseline of the cargo holds, consideration should be given to the influence of these differences on the ship’s resistance performance, structural safety, and workability at shipyards. For S2, the amount of permanent ballast should be minimized to consider the controllability of the loading weight distribution. Finally, for S3 the bottom keel should be properly configured to prevent it from detaching from the baseline of the bow and stern.

List of developments for a new non/minimal ballast ship design

3. Ship Resistance Performance basis Feasibility Evaluation

The ship resistance performance affects the operating cost, and especially the fuel oil consumption. For this reason, the ship resistance performance should be determined in the early design phase. Although the model ship basin test is recommended, for a fast and effective evaluation in this study, a computational fluid dynamics (CFD)-based evaluation was adopted with the model ship basin test results and the sea trial data of an existing 176K bulk carrier. Thus, when the evaluation results have economic feasibility, the model ship-based test will be adopted in the next study. For the model scale CFD simulation, a hull model is generated, as described in Table 9.

Geometry and principal particulars of the model ship for CFD

Regarding the ship’s stability performance, the designed uneven baseline hull form has a larger righting arm compared to the original hull form, as shown in Fig. 4.

Fig. 4

GZ curves of the original and the modified hull form, (a) Laden condition (b) Ballast condition

For the model scale CFD simulations, the Reynolds-averaged Navier-Stokes (RANS) equation-based Wave and viscous flow (WAVIS) software which KRISO (Korea Research Institute of Ships and Ocean Engineering) developed and widely used in Korean ship yards was used. As shown in Table 10, understanding the simulation of the flow around the ship helps in generating an accurate grid arrangement. The grid includes the free surface area with a total of 3.6M grid points for the half domain, which is equivalent to the medium size grid in a previous study (Kim et al., 2011). Starting from the initial graphics exchange specification (IGES) description of the ‘original’ and ‘modified’ hull forms, the commercial program GRIDGEN (Pointwise, Inc.) was used to generate the H-O type multiblock structured grid systems. In the CFD simulation in this study, the free surface was captured using the level-set method, while for the turbulence closure, the Explicit algebraic reynolds stress model (EARSM) was used with Launder and Spalding’s wall function. The details of the numerical methods used can be found in Kim et al. (2011), Kim et al. (2014).

Grid information and distribution

From the numerical resistance test, as shown in Table 11, the effective horsepower (EHP) was predicted to increase from 1.5 to 2.0%, depending on the speed of the bulk carrier, compared to the existing 176K bulk carrier. From the information on the differences between the predicted EHP and the actual instrumented delivery horsepower (DHP) of the existing 176K bulk carrier, the DHP of the designed ship was estimated to have the same ratio for predicting fuel oil consumption as that of the designed ship at the actual scale.

Numerical resistance test results

For more detailed ship resistance performance comparison, model ship basin test has adopted. Fig. 5 shows model ships and Table 12 shows basin test results at same draft (17.7 m) conditions. From the test, EHP increased 5.25% and BHP (Breake horse power) increased 6.55% on average from 12 kt (6.173 m/s) to 15 kt (7.717 m/s) compare to ‘Original’ hull form.

Fig. 5

Model ships, (a) original and (b) modified hull form

Model ship basin resistance test results at same draft condition

Empirically, losses in the cargo capacity can be compensated with an enlarged freeboard by considering the bulk general cargo loading condition. Assuming that the modified and original hull form has same cargo amount, the ‘Original’ hull form’s draft can be reduced to 15.89 m when the draft of ‘Modified’ hull form fixed to 17.70 m. At this time, the BHP gap between ‘Modified’ and ‘Original’ hull form increases more than 12.5% as shown in Fig. 6. Fig. 7 shows model ship basin test pictures, conditions and nominal velocity contour at propeller plane at same displacement condition and Fig. 6 shows RPM and BHP of ‘Modified’ and ‘Original’ hull forms.

Fig. 6

BHP and RPM, (a) original and (b) modified hull form

Fig. 7

Model ship basin tests (above) and nominal velocity contour at propeller plane (below), (a) original and (b) modified hull form at same displacement condition

To compensate loses in ship resistance performance of ‘modified’ hull form, flow stress intensive parts of hull geometry as shown in Fig. 8 shall be improved. Moreover, enlarged beam width can be considered to increase cargo loading capacity of ‘modified’ hull form.

Fig. 8

Comparison of the pressure distribution between the original (above) and the modified (below) hull form

Regarding the sea keeping ability, the characteristics of the ship motion in sea waves are important. As shown in Fig. 9, compared to the original hull form, although the modified hull form shows lack of sea keeping performance in heave and roll motion, the pitch motion characteristics of the ‘modified’ hull form do not significantly differ from those of the original hull form. To analyze ship behavior characteristics, SMTP (Ship motion total package), which is the KRISO’s in-house simulation tool (new version of SURVSHIP (Survivability of ship)) has used (Lee, 2015). In the simulation, 0.02 second time step has applied. Figure 6 shows ship behavior characteristics in the regular wave with beam-sea (entrance angle of 90 degree) condition. Due to uneven baseline, suggested hull form shows lack of seakeeping ability especially in heave and roll motions. In case of Heave motion, it is estimated that waves between bow and stern uneven baseline enlarges ship motion compare to ‘original’ hull form. For roll motion, it is estimated that shorten immersion depth of ‘modified’ hull form enlarges initial roll motion.

Fig. 9

Sample of the designed ship’s motion analysis results in waves under fully loaded conditions (wave height: 2 m, beam sea condition)

To compensate for the losses in the ship motion under waves, relationship between the geometry of mid-ship section and roll damping will be considered (Park et al., 2019). If the propeller diameter is decreased to accommodate for the adjusted ship speed and the engine performance, then the elevating height of the baseline of the cargo holds can be decreased to secure the proper cargo capacity, ship resistance, and seakeeping performance. When considering only the mid-ship section of the suggested uneven baseline minimal ballast bulk carrier, a decrease in the depth of the cargo holds will lead to a decrease in the ultimate bending moment capacity. To compensate for the decreased ultimate bending moment capacity, the weight of the ship’s structure can be increased. For this reason, in order to convince the technical feasibility of the suggested uneven baseline minimal ballast bulk carrier, the structural design evaluation under different sea states should be adopted in the next study.

4. Conclusion

To design a new minimal ballast ship which operate certain amount of permanent ballast for ballast-water free operation, the existing alternatives for ballast water were reviewed. To overcome the lack of berth access and loading constraints of the MIBS / NOBS ‘storm ballast’, the conceptually an uneven baseline basis ‘no or minimal discharge’ alternative so called ‘modified’ hull form suggested. To generate the ‘modified’ concept, a simplified systems engineering-based design approach was adopted. By examining the roles of the ballast water and existing alternatives, seven general requirements for a new minimal ballast ship and one specific requirement for overcoming the penalties of a ‘storm ballast’ were identified. Then, five functional requirements were generated for the uneven baseline minimal ballast vessel. As suggested, the concept has wide and parallel sides compared to the existing V-hull design of a ‘storm ballast’, so the lack of berth access capability can be compensated theoretically. As for loading constraints, the smaller beam size of the suggested concept compare to exiting MIBS / NOBS concept can be helpful in compensating for the load constraints. However, during the model ship basin test, under the same draft conditions, the EHP of ‘modified’ increased 5.25% and BHP increased 6.55% on average compare to ‘original’ hull form. Given the loss in cargo loading capacity, the suggested ‘modified’ hull form’s economic feasibility is assessed at an awkward level. So, resistance performance at same displacement condition has also tested via model ship basin test. From the basin test, more than 12.5 loss in BHP has convinced. From this review result, losses in the cargo capacity and ship resistance performance shall be consider concurrently in the design phase to have technical and economic feasibility. By optimizing the geometry and dimension of the ‘modified’ hull form, a certain amount of loss in resistance performance and cargo capacity shall be compensated in the next study. Although the suggested uneven baseline basis ‘modified’ hull form has many rooms for commercializing, the suggested design, evaluation process and methodologies can be adapted to generate various attempts at developing non/minimal ballast ships to keep the healthy ocean environment from organisms of different ecosystems or a large amount of sterile sea water.

Abbreviations

AUBAFLOW

automatic ballast flow

BW

ballast water

BWE

ballast water exchange

BWM

ballast water management

BWTS

ballast water treatment system

CFD

computational fluid dynamics

CSR-H

harmonized common structural rules

Cf

friction resistance coefficient

Cp

prismatic coefficient

Ctm

total resistance coefficient of model-scale ship

Cfm

Cf of model-scale ship

Cfs

Cf of full-scale ship

Cr

residuary resistance coefficient

Cts

total resistance coefficient of full-scale ship

D-1

regulation about ballast water exchange

D-2

regulation about ballast water treatment

DHP

delivery horsepower

DISV

displacement volume

DWT

deadweight tonnage

EARSM

explicit algebraic Reynolds stress model

EHP

effective horsepower

FOC

fuel oil consumption

IGES

initial graphics exchange specification

ISO/IEC

international organization for standardization/ international electro-technical commission

KPPs

key performance parameters

KB

vertical distance between the keel and the center of buoyancy

MIBS

minimal ballast water ship

MOE

measure of effectiveness

MOP

measure of performance

NOBS

non-ballast water ship

RANS

Reynolds-averaged Navier-Stokes

TA

trim aft

TF

trim forward

Tm

mean draft at a midships

TPMs

technical Performance measures

WAVIS

wave and viscous flow (proprietary brands)

VLCC

very large crude oil carrier

ULCC

ultra large crude oil carrier

Acknowledgements

The initial concept of an ‘uneven baseline minimal ballast water bulk carrier’ was introduced as a proceeding at the 17th International Congress on Maritime Transportation and Harvesting of Sea Resources (IMAM) (Kang et al., 2017) and concretized in this study. This research was supported by a grant from the National R&D Project of KRISO research project PES3000.

Notes

Author name ORCID Contributions

Kang, Hee Jin 0000-0002-8241-3751 ①④⑤

Kim, Kwang-Soo 0000-0001-7548-7157 ③

Choi, Jin 0000-0001-9842-2049 ③

Lee, Yeong-Yeon 0000-0002-0408-6222 ②

Ahn, Haeseong 0000-0001-6330-3744 ⑤

Yim, Geun-Tae 0000-0002-5382-8931 ②

① Conceived of the presented idea or developed the theory

② Carried out the experiment or collected the data

③ Performed the analytic calculations or numerical simulations

④ Wrote the manuscript

⑤ Supervised the findings of this study

References

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Article information Continued

Fig. 1

Design process for a new minimal ballast ship design [derived and edited from (Kang et al., 2016)]

Fig. 2

An initial concept of the adjustable bow, stern and cargo hold baselines for non/minimal ballast operation

Fig. 3

Body plan, modified (left side) and original (right side) hull form

Fig. 4

GZ curves of the original and the modified hull form, (a) Laden condition (b) Ballast condition

Fig. 5

Model ships, (a) original and (b) modified hull form

Fig. 6

BHP and RPM, (a) original and (b) modified hull form

Fig. 7

Model ship basin tests (above) and nominal velocity contour at propeller plane (below), (a) original and (b) modified hull form at same displacement condition

Fig. 8

Comparison of the pressure distribution between the original (above) and the modified (below) hull form

Fig. 9

Sample of the designed ship’s motion analysis results in waves under fully loaded conditions (wave height: 2 m, beam sea condition)

Table 1

Roles of the ballast water in a ship (Isbester, 2010)

Maintain the stability of the ship
Trim and heel control
Secure immersion depth of the propeller
Reduction of slamming
Reduction of the bending moment of the ship
Relieve the shear force of the ship

Table 2

Alternatives for the BWM methods [derived and edited from GEF, U. and IMO, G. P. 2011]

Alternative methods Features Benefits Penalties Suitable Ship type/s
No ballast water
· Zero ballast
  1. Novel hull design

  2. Use of ‘solid ballast TEUs’

Avoids all cost associated BWM Higher hull build/operating cost
  1. Ro-ro pax, car, container, high volume cargo ships

  2. Existing box ships


No or minimal discharge
· Storm ballast (must meet D-2) Wide beam V-hull design Avoids cost of large BWTS Higher building cost, berth access or loading constraints due to wider beam New dry bulk carriers
· Internal ballast (must meet D-2) Fresh water shifted from tank to tank Avoids all cost of BWTS Reduces cargo capacity, air-draught, tank survey/inspection Existing and new container ships, ro-ro pax, liners, livestock carriers
· Portable water (must meet D-2) Only drinking water is added to clean tank/s Avoids costs and loss of space for BWTS Cost of potable water production/purchase Super yachts, cruise liners, some livestock carriers, pax and military vessels

Continuous flow
  • · Longitudinal trunks (meets D-1 and may equivalent to D-2)

  • · Ship buoyancy control (meets D-1 and may equivalent to D-2)

  • · AUBAFLOW (exceeds D-1)

  • · Loop ballast exchange (above D-1 and may approach D-2)

  • · Dyna ballast (exceeds D-1)

Replaces ballast tanks with buoyancy trunks
Multiple valves convert each BW tank into a free flooding buoyancy compartment
Enhanced bluewater BWE pumping
Avoids costs of large BWTS and propeller efficiency gain/s
Avoids costs of BWE pumping and very large BWTS
Avoids costs of BWTS
Higher build costs, risk of biota/sediment accumulation prevent
Costs of multiple valves and control systems, valve servicing, coating and cleaning, slight increase to hull drag
Any sediment/biota accumulating in a low-flow zone
New Seaway-size and other large bulk carriers
Existing and new cargo ships
Existing and new VLCCs + ULCCs
Most types of existing and new cargo ships

Table 3

Business model for a new non / minimal ballast ship design

Task Minimal ballast operation of a ship
Value Enhanced berth access and loading capability compare to existing ‘MIBS’
Revenue Decrease in ecosystem disturbance (meeting D-2), a reasonable hull build cost
Infra Port facilities, ships in operation, rules and regulations, shipyards
Channel Technical and economic feasibility
Stakeholder Ship owners, ship builders, port authorities, classification societies, fishing industries

Table 4

Redefined requirements for the new non/minimal ballast ship design

R1 Maintain the stability of the ship R5 Reduction of slamming
R2 Trim and heel control R6 Reduction of the bending moment of the ship
R3 Secure immersion depth of the propeller R7 Relief of the sheer force of the ship
R4 Ensure the ship resistance performance R8 Harbor operability (berth access / loading constraints)

Table 5

Criteria, thresholds and indicators for TPMs

Type Criterion Threshold
TPM TPM1 Ship stability Meet the rules and regulations
TPM2 Trim and heel control Same as original hull form
TPM3 Resistance performance Minimum increase in EHP
TPM4 Structural strength Meet the related CSR-H**
TPM5 Harbor operability Berth access/loading constraints
**

CSR-H: Harmonized Common Structural Rules

Table 6

Function list for new non/minimal ballast ship design

F1 Function to maintain ship stability TPM1 R1
F2 Trim and heel control function TPM2 R2, R3, R5
F3 Function to maintain resistance performance TPM3 R4
F4 Function to sustain the structural strength of the ship TPM4 R6, R7
F5 Function for berth access and usability for loading facilities TPM5 R8

Table 7

Initial dimensions of the designed ship

Original Modified
Length (p.p.) 282.00 m 282.00 m
Breadth (mld) 45.00 m 45.00 m
Draught laden (Draught ballast TA) 17.70 m (7.70 m) 17.70 m (6.70 m)
Trim −0.175 m −0.176 m
Baseline of cargo holds - 2.45 m elevated
GM (metacentric height) 4.88 m 6.84 m
Deadweight 168,310 t 127,935 t

Table 8

List of developments for a new non/minimal ballast ship design

S1 Uneven baseline of cargo holds F2 and F5
S2 Permanent ballast system only for loading and unloading F4
S3 Bottom keel system F1 and F3

Table 9

Geometry and principal particulars of the model ship for CFD

Original
Modified
Condition Original Modified Original Modified
Tm (m) 17.7 17.7 0.5429 0.5429
S (m2) 19,981 19,113 18.8015 17.9843
Design speed 15 kt (7.717 m/s) 1.3515 (m/s)

Tm (Draft of the ship), S (Area of wetted surface)

Table 10

Grid information and distribution

Grid information

Number of Grid points (half) 3.6M
Number of grid block 13
Average y+ ∼ 80
Half domain size [x,y, z] [−1.5 L ∼ 2.5 L, 0 L ∼ 1.0 L, −1.0 L ∼ 0.03 L]

Grid distribution

Original (bow) Modified (bow)
Original (stern) Modified (stern)

Table 11

Numerical resistance test results

Vs Fn Re CFD (model scale) ITTC Cr Cts Full scale prediction



kt m/s Cf Cp Ctm Cfm Cfs R (kN) EHP (kW)
Original 12 6.173 0.1174 9.55E+06 2.98151 0.60113 3.58264 3.02422 1.40958 0.55842 1.96800 768.7 4745.3
13 6.688 0.1272 1.03E+07 2.94135 0.59370 3.53505 2.98244 1.39624 0.55261 1.94885 893.3 5974.5
14 7.202 0.1369 1.11E+07 2.9053 0.59787 3.50317 2.94452 1.38406 0.55865 1.94271 1032.8 7438.5
15 7.717 0.1467 1.19E+07 2.86288 0.61369 3.47657 2.90987 1.37286 0.56670 1.93956 1183.7 9134.1
Modified 12 6.173 0.1174 9.55E+06 2.97653 0.73649 3.71303 3.02422 1.40958 0.68881 2.09839 784.4 4842.0
13 6.688 0.1272 1.03E+07 2.92307 0.73461 3.65768 2.98244 1.39624 0.67524 2.07148 908.7 6077.3
14 7.202 0.1369 1.11E+07 2.87961 0.74548 3.62509 2.94452 1.38406 0.68057 2.06463 1050.4 7565.3
15 7.717 0.1467 1.19E+07 2.8348 0.75967 3.59447 2.90987 1.37286 0.68460 2.05746 1201.6 9272.6

Vs: Velocity of the ship, CFD: Computational fluid dynamics, ITTC: The International Towing Tank Conference, Cf: friction resistance coefficient, Cp: prismatic coefficient, Ctm: total resistance coefficient of model-scale ship, Cfm: Cf of model-scale ship, Cfs: Cf of full-scale ship, Cr: residuary resistance coefficient, Cts: total resistance coefficient of full-scale ship, R: Resistance, EHP: Effective horse power

Table 12

Model ship basin resistance test results at same draft condition

Vs PE (kW) PB (kW) RPM (1/s) BHP increase RPM increase EHP increase

kt m/s
Original 12 6.173 4391.0 6430.0 69.49 - - -
13 6.688 5528.0 8074.0 75.15 - - -
14 7.202 6871.0 10019.0 80.88 - - -
15 7.717 8538.0 12462.0 86.97 - - -
Modified 12 6.173 4601.8 6832.0 70.62 6.3% 1.6% 4.8%
13 6.688 5819.8 8609.0 76.43 6.6% 1.7% 5.3%
14 7.202 7261.8 10716.0 82.32 7.0% 1.8% 5.7%
15 7.717 8981.0 13248.0 88.36 6.3% 1.6% 5.2%