Development of an ERP Model for Modularly Designed Ships for Medium Scale Shipyards I: Manufacturing Management

Transcription

1 Development of an ERP Model for Modularly Designed Ships for Medium Scale Shipyards I: Manufacturing Management R Sharma and OP Sha of the Design Laboratory, Department of Ocean Engineering and Naval Architecture, Indian Institute of Technology, Kharagpur (WB) , India Enterprise Resource Planning (ERP) has become something of a magic wand for large manufacturing industries because of its capability to integrate different manufacturing modules via online networks and hence providing one window access thereby making the whole manufacturing process integrated with a reduction in inventory. Ship production is not a manufacturing process in a strict sense because of high customisation, widely varying scales of operations and less compatibility between various production processes. Ship production is planned in an activity driven network scheduling system ingeneral and is assumed more as a construction process or assembling process rather than a manufacturing process. An ERP principle is based upon information management and process integration and hence is effective in all manufacturing processes that need to integrate the processes for streamlined, lean and synergised manufacturing. A modular approach to design has been regarded as the new logic for product design and its organisation, as it helps design and manufacturing firms to cope with the present volatile and turbulent environment. This combines the ERP principle and modular approach to design. The ERP principle is used to design the manufacturing management system for the modularly designed ships. In this series of two papers, we discuss development of an ERP model for a medium scale shipyard. Part I, discusses a methodology for manufacturing management: planning and integration of ship manufacturing processes for the modularly designed ships in a medium size shipyard. The manufacturing management is integration driven and is based upon activity based network scheduling. In this work, it is shown that by combining network scheduling, ERP and modular approach to design, the ship manufacturing process will be more streamlined, better planned and executed. AUTHORS BIOGRAPHIES R Sharma received his BE degree in Civil Engineering from the Indian Institute of Technology, Roorkee (formerly University of Roorkee, Roorkee) in 1994 and MTech degree in Ocean Engineering from the Indian Institute of Technology, Kharagpur, in Presently, he is working as Research Associate at the Design Laboratory, Department of Ocean Engineering and Naval Architecture, IIT, Kharagpur, India. OP Sha received his BTech (Hons) in Naval Architecture from the Indian Institute of Technology, Kharagpur in 1980; MS in Ship Production Technology from the University of Strathclyde, Scotland, United Kingdom, in 1982 and PhD in No. A Journal of Marine Engineering and Technology 17

2 Engineering from the Indian Institute of Technology, Kharagpur in Presently, he is Professor in the Department of Ocean Engineering and Naval Architecture at the Indian Institute of Technology, Kharagpur, India. He has been teaching various courses at the graduate and postgraduate level for over two decades. Currently he is involved in many research projects and specialises in the areas of ship design and production, design of high-speed crafts and experimental hydrodynamic investigations on high-speed hull forms. NOMENCLATURE Blue sky item: machinery and material that is outfitted in the open onto a ship before the space is enclosed. ERP: enterprise resource planning. Geographic zone: a geographic volume onboard a ship encompassing a logical grouping of work. Functional zone: a zone where logical grouping of work onboard the ship is carried out and that may encompass several geographic zones. Make ups: small sections of piping and vent that cross erection butts of units and therefore these cannot be installed until the unit is joined to a ship s structure. MRP: manufacturing resource planning. Unit: a structural assembly that is self-contained, selfsupporting, outfitted and erected on a ship or joined with other units during the erection stage of the manufacturing process. INTRODUCTION Ships are complex and complicated products whose design is governed by parameters that are conflicting in nature. Since the parameters are large and the requirements are complex in nature, and their basic natures are conflicting it has been argued that they be designed for optimum performance, bounded by the constraints of design and manufacturing (ie design constraints placed by the owner, statutory bodies etc. and manufacturing constraints placed by the shipyard s facilities). In a restricted choice of ship types it is possible to design and manufacture an optimum design. This is an active area of research 1 but there are the following restrictions: i. The expertise to design and manufacture an optimum ship is very limited, and currently only few ship types have been attempted. ii. The cost of design and manufacturing an optimum ship is very high, and not many design organisations or shipyards can actually afford it. iii. Though, the optimum ship is possible but because of an unstable political world the critical parameters (ie price, supply and demand of oil) that affect the design optimisation of ships change significantly. Even the consumption patterns of sea transportable goods (ie oil, and food grains etc.) do change with the effects of global warming (ie torrential rains affect the crop yields either positively or negatively and irrigation requirements and temperature changes affect the heating requirements hence energy consumption). So the very definition of optimum design for a ship is restricted and one optimum design may not be a favorable design within changed parametric values of price, demand of oil and consumption patterns. The cost of the design and manufacture of an optimum ship is very high so to reduce the unit cost an alternate approach can be taken. In the alternate approach for a given set of constraints (ie incorporating the shipyard s restricted capabilities); a ship is designed not for optimality but for near optimality. Furthermore, driven by the successful implementation of modularisation in the aerospace industry (ie Boeing s series of 747, 767, and 787, are modular versions of the basic Boeing 747 design 2 ), a similar modular approach can be taken for the design of ships. A modular design has been regarded as the new logic for product and organisation design as it helps design and manufacturing firms cope with the changing environment. The promise is that by conceiving products in terms of modules, design and manufacturing, firms can take responsibility for the design and development of separate modules independently (ie but incorporating the inter and intra dependencies between different modules) and a new innovative design can simply be a union of different modules. 3 A new product can be developed at a faster pace as the integration of the new product is ordinarily a union, mix and match of different modules. It is possible by the use of advanced technological knowledge about component interactions that a product can be thought of as an assembly of components and each component designed for near optimality within specified and standardised parameters. A modular approach simplifies the design, and development processes allowing a clear division of labour across manufacturing firms. This allows for the design of integrated and flexible manufacturing schedules for the product. A modular architecture of design is better suited to develop a variational mix of products driven by standardisation, specification, and functional parametric design. Since a product with a modular design allows manufacturing firms to change the product by upgrading or adding different modules without either changing the remainder (ie basic design) or implementing minimum configurational changes keeping any change isolated to a limited domain. 4 Alhough 5 a modular design is more difficult to design than an integral one designers need a deeper understanding of the inner workings of the product, in order to partition and decouple design tasks but technically, a modular design implies a clear division, or more precisely decoupling, between various dependent and independent design parameters. The supply chains for any manufacturing industry consist of various transit points through which the materials are supplied from suppliers and move upwards during the manufacturing processes for one specific Product A and delivery of the specific product A to the targeted/intended customer. For manufacturing planning and execution purposes these are classified as: Backward supply chain: dealing with materials and 18 Journal of Marine Engineering and Technology No. A

3 processes that are required in the manufacturing process of Product A Vertical supply chain: dealing with the manufacturing process or processes required to manufacture Product A within the industry Forward supply chain: dealing with the delivery process of Product A to the customer. The concept of supply chains for a general manufacturing industry is shown in Fig 1a. The shipbuilding industry cannot be classified as a typical manufacturing industry in a strict sense because of high customisation. Since the production process is customised, the delivery process of the specific finished product (Ship A) is smooth. The supply chains for any shipbuilding industry consist of various transit points through which the materials are supplied from suppliers and move upwards during the manufacturing processes for one specific product (Ship A). For manufacturing planning and execution purposes these are classified as: Backward supply chain: dealing with materials and processes that are required in the manufacturing processes for product (Ship A) Vertical supply chain: dealing with the manufacturing process or processes required to manufacture product (Ship A) within the industry. The concept of supply chains for a shipbuilding industry (ie shipyard) is shown in Fig 1b. The manufacturing processes for any manufacturing industry consists of complicated and complex networks of inter and intra related independent/dependent individual processes. To develop an effective and efficient manufacturing management system for a manufacturing industry the stress should be on integrating various/or all inter and intra related independent/dependent individual processes. The integration makes the whole production process more streamlined. For manufacturing planning and execution purposes these are classified as: Backward integration: dealing with integration of different transit points in the backward supply chain that supplies materials and processes required to manufacture Product A Vertical integration: dealing with different manufacturing schedules, activities and processes in a top down approach Forward integration: dealing with integration of different transit points in forward supply chain via which Product A is delivered to the customer. The concept of integration for a manufacturing industry is shown in Fig 2a. As mentioned previously, because of the high customisation in ship manufacturing industry the forward supply chain is absent. Since there is no forward supply chain there will not be any forward integration either. In the case of the shipbuilding industry for manufacturing planning and execution purposes, the integration strategies are classified as: Backward integration: dealing with integration of different transit points in a backward supply chain that supplies materials and processes required to manufacture Ship A Vertical integration: dealing with different manufacturing schedules, activities and processes in a top down approach. The concept of integration for ship manufacturing industry is shown in Fig 2b. To provide, software support for the shipbuilding industry, the integration strategies need to simplify manufacturing which, in turn will simplify software requirements and lead to reduced cost and better implementation. The Enterprise Resources Planning (ERP) approach can be used in manufacturing industries for market forecasting, economic order quantities and shop floor scheduling. Fig 1a and 1b: The supply chains for different industries No. A Journal of Marine Engineering and Technology 19

4 Fig 2a and 2b: The concept of integration of supply chains for different industries The manufacturing management for a shipbuilding industry needs to be flexible in order to incorporate a varying product mix, product volume and manufacturing methods. The important feature of ERP is that it allows efficient scheduling and rough-cut capacity planning. The key requirements from a manufacturing management system for shipbuilding industry are: Integration: to be able to integrate different manufacturing modules Simplicity: to be able to apply simplicity so that people understand them and hence contribute better to the firm s goals and participate in the continuous improvement process Flexibility: to be able to deal with a varying product mix, product volume and manufacturing methods Openness: to be able to provide open system so that individual manufacturing cells or lines control their own activities using local systems and these local systems can be integrated with a central system Accessibility: to be able to provide information in the database that is readily accessible to people through easy to use report writers and the data access features built into relational databases. In our previous works 6,7 we had presented a methodology for manufacturing planning in which the activity based network scheduling was used in the ERP model for a medium sized shipyard and the nucleus marketing driven model in ERP environment for shipyard separately. The present work follows the basic framework of our earlier work 7 and extends the manufacturing management model to further incorporate the modern concepts (ie integration, modular design, and manufacturing). The major differences between the present work and our previous work are The manufacturing management model with ERP applications was presented for ordinarily designed ships but in this paper the manufacturing management model 20 Journal of Marine Engineering and Technology No. A

5 with ERP applications is presented for ships designed with modern concepts like modularisation The manufacturing management model with ERP applications was presented without orienting the shipyard s basic facilities but in this paper the management model with ERP applications is presented with orientation of the shipyard s basic facilities to smoothen the flow of materials The manufacturing management model with ERP applications was presented with only vertical integration but in this paper the management model with ERP applications is presented with backward supply chain integration and vertical integration. Furthermore, we investigate the integration via the basic manufacturing process planning and management for different ship types rather than integration via the basic manufacturing process planning and management for a special ship type. This paper is organised as follows: The first section presents a brief description about the work The second section presents the basics of ship manufacturing processes classification and orientation of different manufacturing shops within a shipyard, of the ERP model and of modular approach to ship design The third section presents the brief description about the model methodology The fourth section presents the backward supply chain management The fifth section presents the vertical integration consisting of the strategic planning and scheduling activity based network scheduling, the system structuring and the system networking The sixth section concludes by identifying some future applications, and further scope of research. Some technical details have not been given in this work to keep the paper of reasonable length. Comprehensive theoretical details and a thorough treatment of all the models of this paper can be found in Sharma and Sha. 8 BASICS OF THE SHIP MANUFACTURING PROCESS Ship manufacturing is typically characterised by the flow of materials (ie materials flow from one shop to another strategically eg material stockyard - primer shop for straightening and registration, shot blasting and priming). The manufacturing process starts with cutting of plates and profiles and later sections are assembled, painted and pre-outfitted before final erection in the building dock. Normally, in a competitive shipyard total time to manufacture a new commercial ship varies between 6 27 months (ie bulk cargo ship ¼ 6 9 months; small to medium sized container ships ¼ 6 12 months; very large container ships, and cruise ships ¼ months; chemical carrier ships ¼ months; and LNG/LPG carrier ships ¼ months). The basic operations in ship manufacturing are, Steel cutting: the cutting is normally autogenous cutting for the heavy plates and plasma cutting for thinner plates. Subassembly: the various section shapes and profiles are manufactured in a profile factory (ie T-sections) with or without robotic control. The rectangular shaped sections are easy to manufacture because their process can be automated and are manufactured by an automatic welding process. The curvilinear shaped sections are difficult to manufacture because their process can not be automated and are manufactured with manual welding (ie with the primary shape from an automatic welding process). Block assembly: in block assembling process different parts of the ships are assembled in different units depending upon the complexities of manufacturing operations. The rectangular shaped sections (ie mainly from the parallel middle body) are assembled primarily by an off-lined robotic welding process in one unit. The curvilinear shaped sections (ie stern bulb, bulbous bow sections, boss sections and other sections with a considerable amount of critical welding) are assembled in another unit. Painting: the process of painting is important and time consuming in the ship manufacturing process. The process includes shot blasting and is done in different units for different sections. Outfitting: the process of outfitting produces different components with pipes. Pre-outfitting: the engine sections are fitted in preoutfitting process in a unit hall. Later the outdoor outfitting of sections is done in the dock area. Grand Block Assembly: the blocks are assembled to grand blocks in the grand block assembly shop (GBAS) and in the area along the dock side. Docking and launching: the docking process is planned in multiple units. Some units are used for storage and production of specific parts for sections and some are used for the manufactured new ship. From here the blocks are erected for the new ship and the ship is launched. The time in the docking process varies from days depending on the ship size. Outfitting Quay: in this process, the final outfitting of the ship and test of systems is done. The time in this process is approximately days. Sea trial: in this process, the ship is named, and leave for sea trial. The time in this process is approximately 7-21 days. Orientation of different manufacturing shops Since ship manufacturing is based upon the process of material flow it is important to orient the different shops such that the materials flow from one shop to another shop efficiently. The strategic orientation of different manufacturing shops is shown in Fig 3. Since the quality enforcement unit is independent of the manufacturing shops in the shipyard it is located such that from its location other manufacturing shops are easily accessible. No. A Journal of Marine Engineering and Technology 21

6 Fig 3: The orientation of different manufacturing shops in a shipyard Basic description of an ERP model Some of the ship manufacturing processes like fabrication of many ship components (eg piping, vent, and machinery foundations) are viewed as an outfitting operation and some of the processes like assembly of the hull and installation and activation of the ship s systems are viewed as a steel assembly operation. The manufacturing processes for shipbuilding are varying in nature and scale so disintegrated systems are a major source of wasteful expenditure. In view of this project planning and scheduling should take a top down approach starting with general goals and objectives and moving progressively towards more details. The level of detail should be defined as per the goals and objectives of program. This will ensure a more consistent production program. The attributes (goals and objectives) selected at an early stage in the ship design/production process provide a common (shared as online data) basis for planning all process-based work groups. This common basis makes it easy to plan the production and engineering tasks for developing producible design and effective build strategies. The scheduling approaches commonly used are the network schedule and Enterprise Resource Planning (ERP) or Manufacturing Resource Planning (MRP). In both of these approaches the strategy is represented in the form of a plan that is a simulation of requirements to achieve the goals. The network approach gives better scheduling and control over key events during production. In a network model various relationships are defined amongst the activities. Since these relationships indicate the connectivity of various activities the network model makes the assessment of the impact of change and reporting the progress of activities easy and accurate. It has become a practice to use an activity-based network scheduling system in customised industries because of the advantages of better scheduling and efficient management of key events. Lack of integration creates poor control over material flow and lacks flexibility in incorporating the effects of changes in production on the production plan. Such a system may suffer from high cycle time and delays in the production schedule. On the other hand the manufacturing industries have been able to successfully achieve inventory reduction, low cycle time, on time delivery, integration of different modules and better control over material flow and production process via the implementation of the principles of Enterprise Resource Planning. The ERP model is costly and requires process reengineering and overhauling in the genetic structure of the production organisation. Fig 4 shows an ERP model for a shipyard. Basic description of modular approach to ship design Any ship or underwater body (ie submarine) is a complex three-dimensional structure and from a design point of view they can be conceived of comprising different hull parts (ie modular part). For example a nuclear submarine can be conceived of eight parts (ie modular part 1: stern hull shape; modular part 2: habitability and machinery room; modular part 3: torpedo room; modular part 4: bow hull shape; modular part 5: navigational tower (ie sail); modular part 6: engine room; modular part 7: control room; and modular part 8: propulsion room (ie nuclear reactor)) and each of these parts can be conceived of to serve some specific objectives with inter and intra relationships between these specific objectives for the final product. This modular description (ie lengthwise arrangement) is shown in Fig 5. Although, the concept of modularisation can be implemented for both naval and commercial ships, in the present work we concentrate on commercial ships. A ship can be conceived of three modularised hull parts or zones: aft body, mid body and fore body. The modular description of three zones is shown in Fig 6. Each zone is designed separately based on its functional and geometric requirements. The functional and geometric 22 Journal of Marine Engineering and Technology No. A

7 Fig 4: An ERP model for a medium scale shipyard Fig 5: The modular description of a nuclear submarine Fig 6: The modular description of the three selected zones for a ship requirements of each zone can be stipulated very briefly as follows: ii. i. Aft Body: technically, the aft body is the most complex portion of the ship and it has the maximum content in terms of construction and assembly of equipments. Furthermore, it is also the most demanding in terms of cost and time. A modularised aft body can suit a range of product mix of ships by combining the modularised aft body with different fore body and mid body modules hence bringing down the cost and time of construction. In this process the machinery, equipment and manufacturing process of the aft body can be modularised. The basic functions of the aft body can be listed as, Hydrodynamics: the flow around the stern, propeller disc and rudder must be smooth avoiding large disturbances. Propulsion: the internal volume is required to house different machineries of the propulsion system. Steering: the aft body shape is designed efficiently with the position of the aft perpendicular and stern aperture. Accommodation: the accommodation is standardised to match with the after body shape to serve the varying requirements of the product mix. Mid Body: the mid body of the ship is designed to carry maximum volume to increase the freight earning capacity of the ship. Although it is simpler than the other two zones of the ship it contains the maximum steel work in terms of weight. The variational para- No. A Journal of Marine Engineering and Technology 23

8 meters in this zone include length, bilge radius (ie of midship area), and prismatic coefficient. The mid body is subjected to the constraints of functional and requirements such as: Cargo: the different internal arrangements are designed for varying product mix (ie containers, petroleum, oil and lubricant (POL) liquid cargo, bulk cargo and general cargo, etc.). Cargo volume: the cargo volume is varied to suit a product mix by adjusting the following geometric characteristics in this region: Length (ie parallel middle body length). Block coefficient (ie sectional area curve). Depth. Manufacturing friendliness: it is incorporated in the product mix by keeping the internal volume the same but varying the bilge radius and thereby altering the length of the parallel middle body. iii. Fore body: technically, the fore body is a highly curved, three dimensional and complex structure which is difficult to manufacture. A standardised fore body can reduce production cost and time substantially. The basic requirements of the fore body can be listed as, Hydrodynamics: the different requirements of product mix (ie design draught: container ship design draught is lower than that for a tanker and ballast draughts that are important for tankers and bulk carriers) are to be incorporated in the modular design. The hydrodynamic design of the bulb should also take into account the range of speeds for the varying product mix. Manufacturing friendliness: the fore body shape is to be designed so that it can be manufactured easily and is able to house standardised anchoring and mooring equipments for the product mix. Additionally, the modularised design of the three zones that satisfies the separate functional requirements described above should also be able to satisfy the overall geometric constraints as, The parallel middle body is to be adapted to suit the different requirements of the product mix. For example, the depth is varied within a limit by changing the above water portion of the ship to suit the requirements of product mix to maintain the required freeboard. The block coefficient and longitudinal centre of buoyancy are optimised corresponding to the specific design Froude number in the process of modularisation of the three zones. The overall deck area is designed to efficiently contain cargo arrangements/requirements. The modular three zones are merged into a continuous three dimensional faired body while maintaining C 1 continuity (ie tangent plane continuity meaning that the waterlines and buttock planes in the merged regions: aft body and mid body, mid body and fore body; are smooth and fair having first order continuous derivatives). Basically the modularisation of ship hull comprises of the following steps: The technical and building specification for the product mix are defined. The desired specifications for the modular ship including its functional and other features are identified. The specifications for the aft region, fore region and mid body region for the range of identified ships are defined. The ship length is divided into three distinct zones (ie aft body: extending from aft till forward of engine room forward bulk head; fore body: extending from fore end of the ship till aft of fore peak bulk head and mid body: consisting of the middle portion between the aft body and fore body). The functional requirements of the three zones thus defined are identified. The constructional parameters for the said three zones based on the available input database and their functional requirements are defined. The modular design of the said three zones satisfying the separate functional requirement and the overall geometric constraints is generated. The zones are merged into a single continuous three dimensionally faired body to thereby obtain the modular ship. An example of modular approach A brief preliminary and technical specification of an identified product mix is designed by analysing the shipping market. The broad product mix identified is as, 550 to 650 TEU feeder container vessels to DWT product tankers for short sea voyages to DWT bulk carriers and multipurpose cargo carriers. This is further analysed to arrive at specific vessel types suitable for production in one selected shipyard (ie Indian shipyard), the specific vessels are, 550 TEU feeder container vessel for 14.0kts to 15.5kts design speed. 600 TEU feeder container vessel for 14.0kts to 15.5kts design speed. 650 TEU feeder container vessel for 14.0kts to 15.5kts design speed DWT Product Tankers /Bulk Carriers /Multipurpose Cargo Carriers for 13.5kts to 14.5kts design speed DWT Product Tankers /Bulk Carriers /Multipurpose Cargo Carriers for 13.5kts to 14.5kts design speed DWT Product Tankers /Bulk Carriers /Multipurpose Cargo Carriers for 13.5kts to 14.5kts design speed. The features of the ship satisfying modular concept are identified by utilising the client requirement database consisting of the constraints of shipyard and the feeder contain- 24 Journal of Marine Engineering and Technology No. A

9 er and POL service trade patterns for short sea routes around Indian coast. The variation in main dimensions and ship particulars are determined: Length ¼ m; Breadth < 19m; Depth ¼ m; Draught (fully loaded) ¼ 6.6m for feeder container vessel and 7.8m for the other vessels; Draught ballast ¼ no special requirement for container vessel, 5.5m aft and 4.0m forward for other vessels; and Block coefficient ¼ The functional specifications of the aft region, mid body region and fore region are arrived at by analysing the technical information and preliminary design calculations for the given range of ships. The functional specifications are: the vessel with length 113m should have the smallest length of parallel middle body; the vessel length should be changed by steps of 7m to generate ships of length 120 and 127m; this length variation to be obtained only by changing the parallel middle body; the depth variation between 10.3m to 11.0m is to be obtained by extending the above water portion of the hull only without affecting hydrodynamic performance of the ship; for an optimum hydrodynamic performance of the entire range of products, it was decided to have the LCB vary between 0m and 1m forward of mid-ship; the fore end should be suitable for two draught operations (ie suitable for container ships and suitable for tankers, bulk carriers and multipurpose vessels) and the stern is to be standardised for the given range of vessels. As shown in Fig 6, the ship length for the entire product mix is divided into three distinct regions by analysing the further technical calculations and manufacturing information from the shipyard. The functional requirements of the three regions of the ship hulls are arrived at by naval architecture calculations and these are identified for the three separate regions: aft region - to be suitable for providing a uniform distribution of wake in the propeller disc region for all vessels, to have adequate volume to provide propulsion and auxiliary machinery for all vessels, to have adequate area in the upper deck region to provide standardised accommodation; mid body region - to provide adequate volume based on the payload requirement of all vessels, the fore and aft ends of the mid body region should merge with the fore region and aft region respectively in such a manner that the fore shoulder and aft shoulder of the ship hull are smooth and do not create adverse wave making effects and the distribution of the area along the length of this region is to be such that the required LCB of the vessel is attained and fore body - the functional requirement of the fore body is primarily hydrodynamic which is to have a bulbous bow to operate at 6.6m draught for the container vessels and to have a bulbous bow to operate at a full load draught of 7.8m and a ballast draught 5.5m aft and 4.0m forward for all other vessels. The construction parameters of the three regions have been identified utilising the manufacturing requirements: aft region - one stern shape is identified as a standard stern for all products mentioned above, two standard accommodation plans suiting the stern have been designed for the container ship having a 6-tier accommodation and a 5-tier accommodation for all other vessels; mid body region - two mid bodies with bilge radius 2.2m and 3.5m are identified with different parallel middle bodies which can be selected by the builder based on the manufacturing requirements; fore body region - two fore body shapes are identified one for container vessel and another for all other vessels, the fore body shape is designed taking into account ease of manufacture. The shapes of the three regions are developed. The Fore body (F1) with bulbous bow corresponds to the container ship having a design draught of 6.6m for entire speed range of kts. The Fore body F2 with bulbous bow corresponds to bulk carrier/tanker/multipurpose ship for the entire speed range of 13 to 14.5kts. These are shown in Fig 7. The Stern S for the entire product mix given above is shown in. The Mid body M1 with 2.2m bilge radius corresponds to the overall block coefficient (C B ) ¼ The Mid body M2 with 3.5m bilge radius gives a large parallel middle body and corresponds to the overall block coefficient (C B ) ¼ These are shown in Fig 9. Fig 7: The alternative fore body shapes F1/F2 Fig 8: The aft body Shape S A set of alternative ship hull forms are developed using a combination of aft body S, mid bodies M1/M2 and fore bodies F1/F2. Additionally, the aft body-mid body region and the mid body-fore body region are merged to obtain smooth continuous hull forms. Using two fore bodies (F1 and F2) and two mid bodies (M1 and M2) and one stern (S) four forms are generated. Three ship lengths are generated in each combination by elongation of parallel middle body (M11, M12, M13 and M21, M22, M23). Thus there are a total of twelve forms. The two mid body modules are No. A Journal of Marine Engineering and Technology 25

10 Fig 9: The alternative mid body shapes M1/ M2 generating by varying the bilge radius (ie one with 2.2m (M1) and the other with 3.5m (M2)). This is done by adjusting prismatic coefficient and keeping the block coefficient constant. Thus M2 has a longer parallel middle body and more pronounced forward and aft shoulders compared to M1. The particulars of the entire range of vessels are listed in Table 1. The separate and full details on the designs of twelve modular hull forms listed in Table 1 can be found in our other works. 9,10,11,12,13 A BRIEF DESCRIPTION OF THE PRESENT MODEL In an ERP model the demand is driven by the prime schedule items (ie items which are at the top of the bill of materials). Since a ship is a complicated product it is very difficult, time consuming and inefficient to define the prime schedule for the complete ship and plan the entire manufacturing process in a top down manner. Additionally, in the process of shipbuilding the intermediate manufacturing stages are difficult to demarcate and evaluate (ie definition that drives the demand). This makes the progress reporting difficult to track and the impact of any variation in the proposed plan of work is difficult to assess. In the ERP model, considering these facts we subdivide the ship manufacturing process into interim products or sections (ie blocks), which in turn are further broken down into a series of activities or tasks. Therefore, in our model the activities required to manufacture the interim products are used as the ERP prime schedule items. Material planning as demanded by the manufacturing plan is structured beneath the appropriate prime schedule item. In the ship manufacturing process the interim products are divided into the following categories 14,15,16 : Ground assembly and outfit (GA&O) prime schedule items: GA&O items consist of steel fabrication, assembling, joining and erection of units along with the shop fabrication and installation of items which are installed prior to erection and any testing performed prior to erection. Onboard prime schedule items: these items consist of the fabrication and installation of make ups and blue sky items as well as remaining work and tests performed on board the ship. For the different ship types (ie in this work tanker/bulk carriers, container vessels and multipurpose cargo vessels), the planning process is carried out in a top down manner. It starts at the conceptual level where the important milestones are conceptualised and clearly identified and the manufac- Sl. No Model name Fore body shape Mid body shape Bilge radius (m) Length (m) Breadth (m) Ship type 1 SM11F1 F1 M container 2 SM12F1 F1 M container 3 SM13F1 F1 M container 4 SM21F1 F1 M container 5 SM22F1 F1 M container 6 SM23F1 F1 M container 7 SM11F2 F2 M tanker/bulk carrier 8 SM12F2 F2 M tanker/bulk carrier 9 SM131F2 F2 M tanker/bulk carrier 10 SM21F2 F2 M tanker/bulk carrier 11 SM22F2 F2 M tanker/bulk carrier 12 SM23F2 F2 M tanker/bulk carrier Table 1: The overall matrix for the twelve modular hull forms 26 Journal of Marine Engineering and Technology No. A

11 turing goals are achieved through these milestones. These milestones and manufacturing goals serve as the basis to design efficient GA&O and onboard build strategies. The prime schedule network is planned on the basis of the build strategies and the process lane strategies along with the ship s erection schedule and completion schedule. This forms the networking in the ERP system. Definition and scheduling of activities, which comprise the top of the ERP demand bills (human and material resources), is part of a sequential planning activity process. In general Fig 10 shows when planning and scheduling documents are to be developed in relation to the key milestones (ie assignment of contract, start of fabrication, keel laying, launching, and delivery), and additional planning. 14,15,16,17 The amount of strategic planning and scheduling done prior to contract sign vary with the nature of the ship (ie in this work, the decreasing order is oil tanker, container ship and multi purpose cargo ship). BACKWARD SUPPLY CHAIN MANAGEMENT As shown in Figs 2 and 4, for backward integration the supply of materials required for manufacturing via different suppliers is networked. Additionally this will enable the implementation of pre-contract business processes that will integrate the backward supply chain with the shipyard design/manufacturing to support build strategies, master scheduling, resources allocation, capacity analysis, and improved price estimation. The challenges in the world of shipbuilding are to integrate the various materials and resources suppliers (ie suppliers involved at different stages of the manufacturing and in the case of consortium of shipyards, the shipyards involved at different stages of the manufacturing). This requires shipyard-supplier and shipyard-shipyard integrations and these integrations are the key elements in improving the efficiency of shipbuilding back- Fig 10: The timeline for manufacturing planning No. A Journal of Marine Engineering and Technology 27

12 ward supply chains. In this work we propose an integrated backward supply chain in which the shipbuilding supply chain is organised, instantiated and networked online to provide single window access. The backward supply chain integration, and sourcing is shown in Fig 11. The supply chains are complex and involve many independent, inter dependent, and intra dependent variables. Therefore the management of supply chains requires the integrated efforts of each unit in supply, design and manufacturing which in turn require the complete information into the status of all the recent data that drive demand in each unit. The aim is to provide right information to the right place at the right time. In Fig 11 we establish backward supply chain integration and sourcing via the shipyard s integrated data centre which is based upon an OSC (ie open source code) operating system. Additionally the integrated data centre is interlocked within a reference architecture that accommodates diversified operations and processes. The integrated backward supply chain links management, engineering design, customers, and suppliers in a shipyard. The architecture of an integrated backward supply chain is shown in Fig 12. To describe the architecture of an integrated backward supply chain, it is easy of think SIDC as an information manager. Since in modern times suppliers and customers may be linked through a liaison agency the information manager is very much to be desired. There are two possible ways for the shipyard to get a contract for shipbuilding and these are: the shipyard explores the market, conceptualises a product and then markets that product via a proposal to prospective owners or order placing agencies; or more conventionally, an owner or order placing agency based on their requirements of market demands places an order to the shipyard. At first the shipyard starts with pre-procurement planning (ie material and processes requirement planning) and then it selects and lists the suppliers. Once the order is placed for a ship, the shipyard starts with procurement planning (ie material and processes requirement planning), and subsequently it selects, lists, and manages the suppliers via the supplier management. After, the preprocurement or procurement planning, the procured or to be procured materials and processes are planned and managed with logistics support and planning. When the flow of materials and processes is decided this forms the collaborative planning for the shipyard. Utilising the flow of materials and processes the manufacturing planning is done for the ship. At this stage, if additional materials and processes are required the shipyard selects, lists and manages the suppliers via the supplier management and similarly they are planned and managed with logistics support. After the successful implementation of the manufacturing planning the manufactured ship becomes ready for delivery. Depending on the materials and processes required at this stage, the shipyard selects, lists and manages the suppliers via the supplier management. In this way, all the processes from order placement (ie via owner/order placing agency) to delivery are integrated in the backward supply chain. This is shown in Fig 13. For the modularly designed ships (ie in this work oil tanker, container ship, and multipurpose cargo ship) the demands for materials and processes are broken into individual demands for specific modular parts (ie aft body, mid body and fore body). The orders are placed by an individual manufacturing shop via a centralised system and the supply pattern is scheduled. These individual demands are added and arranged to get the desired configuration of the ship. Similarly the individual schedule of items are arranged to obtain the desired configuration of the ship. Fig 11: The integrated backward supply chain Fig 12: The architecture of an integrated backward supply chain Fig 13: The processes in an integrated backward supply chain 28 Journal of Marine Engineering and Technology No. A

13 VERTICAL INTEGRATION Strategic planning and scheduling An ideal shipbuilding management deals with the optimum organisation and construction methodology required to manufacture the product mix contained within the shipyard s aims and objectives. The aim of build strategy is to realise the shipyard s ambitions and it is derived from basic manufacturing operations to strategically plan the manufacturing of ship for optimum construction time. In the definition of build strategy we consider the shipyard s capabilities, standards and areas of interests and combine these with the requirements of the assigned contract. The build strategy is suitably incorporated in the hull block definition and planning, and key date master schedule and it includes both preliminary and detailed stages of ship design and manufacturing. In our integrated model, the build strategy provides input to the design and includes strategic and detailed manufacturing process analysis. Continuing from the section entitled Basic ship manufacturing processes and Fig 3, we define the common basic build strategy 18 for the selected product mix (ie tanker/bulk carriers, container vessels, and multipurpose cargo vessels) for a shipyard. This is shown in Fig 14. The detailed build strategy 18 for the same is shown in Fig 15. Important milestone schedules and high-level manufacturing goals are planned and agreed initially to start with all the concerned groups first. Important milestone schedules define key events such as contract award, keel laying, start of fabrication, launch, trials and delivery. Fig 14: The basic build strategy for the selected product mix for a shipyard Fig 15: The detailed build strategy for the selected product mix for a shipyard No. A Journal of Marine Engineering and Technology 29

14 The scheduling is based upon key business plans, contract requirements and other factors such as the expected availability of resources (ie manufacturing resources and facilities and human resources) in the shipyard. High-level manufacturing goals show the amount of work to be done on the ground and the amount performed onboard. The goals also show the manufacturing of certain parts of the ship relative to the important milestones. The manufacturing goals 14,16 for the selected product mix are listed in Table 2. Similar to the manufacturing groups the design is also organised according to the classes of problems in a manner that complements planned zoning. These zones directly correspond to material procurement zones. For commercial ships, there are three groups: hull, machinery and outfit, and superstructure. The design activities are divided into: basic design, functional design, transition design and detailed design. In each of these design stages drawings and material lists are developed by the system. Each design stage more clearly defines material requirements. The de- Sl. No. Machinery Spaces Cargo Decks Accommodation Cargo and Ballast Tanks (Container ship will be carrying unitised cargo, and whereas oil tanker will carry liquid. Tank hold space will have cargo piping system) Stern Bow GA & O Assembly area Inner bottom piping, manholes and ladder complete. Back-up structure for deck equipment and foundations installed. Large diameter piping (ie the decreasing order is oil tanker ship, multipurpose cargo ship, and container ship), fans, ventilator spools and curtain plates. Outfit complete except submerged pumps and vertical ladders. Tank piping including stern tube LO (i.e. the decreasing order is oil tanker ship, multipurpose cargo ship, container ship), ladders and manholes. Ballast piping, ladders and manholes installed GA & O Machinery unitisation area Auxiliary machineries (including all equipment except ME), complete hydroed and flushed. Pipe racks including machinery, valves, electrical items, air, fire and foam items. Piping hydroed flushed and lagged. Fan room units complete, hydroed and flushed. GA & O Pre-outfit area Sea chests complete. Fully outfitted except for make-up pieces at block breaks. Install submerged pumps. Outfit complete except for make-up to machinery space. - Install valve operator reach rods. Steering gear unit complete, hydroed and flushed. Time is given only as +/- X wks (i.e. weeks) after launch. Table 2: The manufacturing goals for the product mix Mooring equipment and fitting install. Hot work on deck complete. Rudder trunk bored. - Forward stores and paint locker complete. All deck outfit including mooring and anchor handling complete. On-Board Complete by stern release Cores land X wks prior to release, install make-ups and remove temporary staging. Core makeup complete X wks after release. Make-up between aft tanks complete within X wks after release. On-Board Complete by launch Power and automation complete, ME connect make-up X wks after launch. Make-ups with casing complete after X wks launch. Make-up between forward tanks complete within X wks after launch. Submerged pumps installed. - Distribution systems complete, equipment hookedup, joiner work complete X wks after launch. - Cargo and ballast system complete. Complete stern tube within X wks after release. Final align shafts and installation complete X wks after launch. - Make-up to distribution system on deck complete X wks after launch. On-Board Post launch Turn over ME X wks after launch. Deck outfit complete X wks after launch. Flooring, paint and finish work complete X wks after launch. Tank outfit complete X wks after launch. Aft deck outfit complete X wks after launch. Forward deck outfit complete X wks after launch. 30 Journal of Marine Engineering and Technology No. A