bluuebunny/crossref_metadata_2025 huggingface dataset:
Marine Supply Chain Management
Authors: Fleischer M. , Kohler R. , Fellow T. Lamb , Bongiorni H. B.
Published: January 2021

The US shipbuilding industry finds itself pressed on many sides by dwindling government and commercial ship orders. Without significant improvement in performance, the US shipbuilding industry will contract to the minimum that can sustain government and Jones Act commercial ship demand. There has been considerable benchmarking of the US shipbuilding with other shipbuilding countries and other US and foreign industries. In these studies, the improved management of the supply chains has been found to be an important way to improve performance. The 1996 21s' Century Agile Shipbuilding Strategies report identified improvement in the relationship between shipyards and their suppliers as one of the highest priorities. In the marine industry over 50% of the cost of the delivered product is for material and equipment. When significant turn-key subcontracting is used this can increase to 75%. Over the past two decades, most US shipbuilders acknowledged that their productivity was significantly lower than world class shipbuilders. More recently they have acknowledged a material cost differential of up to 33%. Clearly, the cost of material is one of the major sources of the lack of international competitiveness of the US marine industry. The performance of the US automotive and aerospace industries has improved significantly by focusing on and improving their supply chain management. Much of Boeing's and Chrysler's improvement has been attributed to successful change in this area. This paper describes the results of a project that analyzed supply chain management in the marine industry as a way to develop a set of best practices.
Product-Oriented Design and Construction (PODAC) Cost Module – An Update
Authors: Trumbule John C. , Dougherty John J. , Deschamps Laurent , Ewing Richard , Greenwell Charles R. , Lamb Thomas
Published: January 2021

During the past several years the US Navy and the shipbuilding industry have been working together to develop a cost estimating tool that is sensitive to manufacturing processes and techniques. The Product-Oriented Design and Construction Cost Model (PODAC) Project's charter is to develop a product-based, production driven cost estimating tool that will be used by shipbuilders and the Navy to assess the cost of innovated and advanced technologies proposed for naval application. This paper will highlight the progress of the model development and the future direction of the project. Additionally, the PODAC Integrated Product Team (IPT) has been installing and implementing the PODAC Cost model at five major U.S. shipyards and within the Naval Sea Systems Command (NA VSEA) over the last twelve months. A structured evaluation of the model has taken place at several shipyards. The evaluation process was conducted in terms of technical or engineering trade-off studies. The findings and recommendations of one of these studies are discussed.
MARITECH’s Shipbuilding Information Infrastructure
Authors: Rando Thomas , Fernholz Danielle
Published: January 2021

The goal of the Shipbuilding Information Infrastructure is to improve the accessibility and value of enterprise information for US shipbuilders. This promises notable benefits because the shipbuilding industry has significant information requirements. A ship may comprise more than a million parts, each of which must be managed through the many design, manufacture, test and logistics processes. The ability to share information across processes and organizations not only streamlines existing processes but offers the opportunity to identify new, improved processes. In order to strengthen the industry as a whole, the shipbuilding information infrastructure has to satisfy the following technical requirements:An information technology gap separates the large, medium and small shipyards.The information technology staffs at most shipyards are experts in shipbuilding process requirements but not in system-level computer technologies.Shipyard information systems must be reliable and maintainable yet often need to be customized to suit an individual shipyard. This paper describes how the SHIIP and SPARS projects have used a deliberate combination of component-based software, Internet protocols and a portable computing platform to satisfy these technical requirements. It describes how the SHIIP project has demonstrated that the Shipbuilding Information Infrastructure can be used for information sharing within a shipyard and how the SPARS project has demonstrated that the same infrastructure can be used for information sharing among shipyards, their partners and suppliers.
Angular Distortion Due to Fillet Welding and Its Straightening
Authors: Okumoto Yasuhisa , Yanai Hideharu , Matsuzaki Shin-ich
Published: January 2021

In order to increase the productivity of shipbuilding to respond to current situations such as decreasing numbers of skilled workers and aging of workers in the shipyard, mechanization and robotization have been accelerated. To apply them effectively, the current fabrication and assembling system of ship hull has to be reviewed so that the dimensional accuracy of the hull block and its components increase particularly. Accordingly, the authors had developed an "accurate production system" for the fabrication and assembly of flat block, which was based on advanced accuracy technology and modem automated machines. This report concerns the deformation due to the filet welding of longitudinals on a skin plate and its straightening; the estimation of welding deformation, especially angular distortion, and its straightening method using a press roller which was developed newly in this automated production line. In order to clarify the power of the straightening machine, non-linear FEM analysis was carried out.
Implementation of a State of the Art First Operations Shop in a Second Tier Shipyard
Authors: Cahill Patrick , Shank Robert , Crilly Patrick , Kelly Gordon , Jutla Tarsem , Weeks Ted
Published: January 2021

Bender Shipbuilding and Repair Company, Inc. is in the process of modernizing a second tier shipyard and creating a state of the art facility which will house the only steel plate laser cutting machine in the U.S. shipbuilding industry, and one of the largest laser installations in the world. The laser machine tool will be installed in a state of the art First Operations Shop currently under construction at Bender Shipbuilding in Mobile, Alabama. By using a Maritech Consortium partnership with Caterpillar, Inc., Bender was able to completely evaluate cutting system options and design a complete First Operations process to support just in time production of steel plate parts. In addition, Bender and Caterpillar have teamed to pursue innovations in joining technology that can only be achieved with the precision machining capability of a laser machine tool. A Title XI Shipyard Modernization loan guarantee is being used to provide the working capital necessary to build the $6 million facility. This paper will review the state of technology of laser cutting in heavy manufacturing and in shipbuilding, provide an overview of Bender and Caterpillar's cutting project, present test results from an ongoing series of joining concept tests designed to initiate a rule change with the American Bureau of Shipping, and provide a comprehensive description of Bender's implementation plan for the First Operations Shop.
A Method for Machine Arrangement Design Evaluation and Pipe Construction Material Estimation
Authors: Wu J.K.
Published: January 2021

This paper describes a method to estimate the pipe construction materials based on the Orthogonal Routing Method and three classes of design information, including equipment arrangement drawings, piping system diagrams, and equipment catalogs. However, this method does not need detail pipe routing design information. The pipe construction material estimating method has been tested by using the design information of the lubricating oil piping system of the main engine of an 8000-ton oil tanker. The result is very encouraging, only 10% underestimation. Such a material estimating method is a useful engineering tool from the Design for Manufacturing and Concurrent Engineering points of view.
Laser-Cutting and Welding of DDG-51 Structural Shapes
Authors: Blomquist Paul A. , Forrest David L.
Published: January 2021

The application of high-power industrial lasers to the production of structural shapes for shipbuilding has been analyzed. Requirements for T-and I-sections used in a DDG-51 class vessel were used to evaluate a cost/benefit ratio for fabricating shapes vice purchasing hot rolled sections. Results of the study indicate that fabricated shapes offer significant tangible and intangible benefits to the shipbuilder, and that the entire shipset of T's and I's can be cut from plate and welded to actual net shape for less cost than the purchase price of stock lengths of hot-rolled shapes. Savings from elimination of complex layout and cutting operations further add to the benefit. The high speed and high accuracy of modern industrial lasers makes possible an efficient, flexible, and cost-effective approach to the production of structural shapes. A further benefit is the potential to design a ship with structurals having the same depth, vastly improving the speed of outfitting such as the installation of piping, wireways and vent runs.
Developments in Bulb Flats and Other Hot Rolled Special Steel Profiles for Advancing Commercial and Naval Shipbuilding in the U.S.
Authors: Braidwood Iain , Lofthouse Geoff
Published: January 2021

Special steel profiles are increasingly being used for commercial and warship construction to reduce production and life cycle costs. In particular, bulb flats (Holland profiles), manufactured by special profiles businesses, are increasingly being used for plate stiffening in warships and naval auxiliaries. Examples are the UK's Type 23 Frigates, the LPH HMS Ocean, Watson Class Sealift ships and the Dutch LPD HrMs Rotterdam, as well as, looking to the future, the UK Type 45 Destroyer. Some comparison will be made of naval vessel construction on both sides of the Atlantic, particularly looking at the advantages that bulb flats can bring to naval vessel construction. This paper will discuss the challenge of introducing new shapes, examine the state of the art in the production of special steel shapes and describe metallurgical developments that enable the delivery of shapes with required structural performance and suitability for production. Shipbuilding developments such as laser welding are being addressed with a view to the manufacture of special profiles, particularly where tolerance and chemical composition issues need to be addressed. Future lightweight vessel construction may involve a mix of aluminium, steel and composite structures. Special profiles can be developed to assist in the joining of these different construction materials.
Production Management System for Medium-Sized Shipyards
Authors: Okumoto Yasuhisa , Kasama Masaaki
Published: January 2021

This paper describes a new production management system designed specifically for the midsized or small shipyards. The system, called OPMIS (Object-oriented Production Management and Information System), was developed by the authors and has been applied successfully to the hull block assembly at Kanda Shipyard in Japan. The features and benefits of OPMIS are illustrated, including work scheduling and management, material and budget data, and assembly shop simulation. A key advantage of the program is that it has been planned to operate with both MS Office and Visual Basic on Windows 95/98 PCs in a user-friendly environment.
Development of a New Finite-Element Method to Analyze Deformation of Plate Due to Line Heating
Authors: Seo Seung Il , Yang Yoon Ho , Jang Chang Doo
Published: January 2021

The line heating process has been used to create curved surfaces of ship structures. However, because it depends on a worker's skill and experience, it has been a factor in preventing the automation of shipyards and in consuming labor costs. In this paper, to reduce the trial-and-error procedure of line heating work by simulating the deforming process of a plate, a finite-element analysis method is proposed. A new element, called the line heating element, is defined and applied. The line heating element is assumed to have orthotropic material property. Shrinkage forces and moments resulting from line heating are obtained by integration of inherent strains formed by local heating and cooling. The shrinkage forces and moments at the inherent strain region are converted to equivalent nodal forces by the energy principle. Results calculated using the line heating element show good agreement with the results obtained by the commercial finite-element analysis code.
The National Shipbuilding Research Program Welding Fume Study
Authors: Chute Daniel O. , Christ Bradley W.
Published: January 2021

This paper presents the results of a study evaluating the impact of anticipated reductions in OSHA worker exposure limits for airborne contaminants, nickel (Ni), manganese (Mn), and hexavalent chromium (Cr6) on the shipbuilding industry. As part of the study field evaluation, air monitoring and data analysis were conducted to measure the effectiveness of a series of exposure control methods including fume extractor guns, ixed fume extraction systems, portable fume extraction systems, low fume welding wires, downdraft/backdraft tables, and fume iltration devices. Six shipyards participated in this study. The study concluded that the cost of compliance increases greatly with lower exposure limits. It was recommended that the shipbuilding industry continue to develop and evaluate feasible control measures in anticipation of revised standards.
Towards a Practical Means of Predicting Weld Distortion
Authors: Bruce George J. , Yuliadi M. Z. , Shahab A.
Published: January 2021

Distortion due to heat input from welding is well known, but difficult to predict. It causes rework, adds cost and may affect strength. The paper addresses the complexity of the problem using a neural network model as a predictor. This gave good agreement with experimental distortion data. The sensitivity of results to different variables, including chemical composition, is reported.
Modeling and Analysis of Labor Cost Estimation for Shipbuilding: The Case of China Shipbuilding Corporation
Authors: Chou Chia-Chan , Chang Pao-Long
Published: January 2021

Taiwan's shipbuilding industry confronts serious competition in the international market. Shipyards must acquire market information and give accurate quotations in order to obtain shipbuilding orders. The estimation of labor cost for shipbuilding is very important during the quotation stage. It is the purpose of this paper therefore to investigate the prevailing factors for labor cost and to construct models of man-hour estimation for building new ships for the China Shipbuilding Corporation. According to an empirical analysis, the effects of factors such as hull steel weight, main engine output, compensated gross tonnage, and technological progress on man-hours for construction have been confirmed. Furthermore, the comparison between the actual and estimated values for man-hours of construction shows that the derived models are highly accurate.
European Maritime Research: Objectives, Organization, Content, and Parallels with the NSRP Programs
Authors: Goldan Michael
Published: January 2021

Research and development (R&D) is a strategic issue for the European maritime industries, which at the brink of a new millennium are facing various challenges such as maintaining a competitive edge against worldwide competition, responsible exploitation and management of marine resources and combining competitiveness and profitability with care for safety and environment. Recognizing the benefits resulting from coordination of R&D efforts for both industry and European Union, the Maritime Industries Forum (MIF) established in December 1994 a R&D Co-ordination Group, which took upon itself to develop a R&D Master Plan setting thereby a reference for maritime research in the years to come. The paper addresses the various aspects of the European Maritime Research with respect to objectives, organization and content, highlighting the initiatives undertaken by the maritime industries in setting R&D objectives and programs, in particular the work of COREDES, the R&D Committee of CESA (Committee of European Shipbuilders Associations). The paper further addresses the EU Fifth Frame Programme and its references regarding Maritime R&D, in particular Key Action 3 (Land Transport and Maritime Technologies) and some of the instruments for facilitating R&D activities, and gives the main lines of R&D areas and issues. Parallels between European maritime research and the U.S. NSRP programs based on available information are drawn showing the differences and commonalities between the two programs. Finally, the paper highlights the emerging contours of the EU Sixth Frame Program and suggests possible areas for future cooperation in maritime research between U.S. and Europe.
Evolution of STEP (ESTEP): Exchange of Shipbuilding Product Model Data
Authors: Gischner B. , Kassel B. , Lazo P. , Wood R. , Wyman J.
Published: January 2021

Evolution of STEP (ESTEP) is a task within the MARITECH-ASE Integrated Shipbuilding Environment (ISE) Project building upon the work of the MariSTEP consortium and the NIDDESC standards development efforts. The purpose of ESTEP is to validate product model standards for the shipbuilding industry, implement product model data translators, and to further the development of Shipbuilding Application Protocols. Three of the major goals of ESTEP are developing a production-quality ship structure data exchange capability, expanding shipbuilding piping implementation efforts, and the exchange of parts and part libraries. Piping applications between the plant design industry and the shipbuilding industry are similar, and the AP used for translation of plant piping data (AP227–Plant Spatial Configuration) is much further along in the ISO process than the ISO Shipbuilding Piping AP (AP217). Both application protocols have been analyzed to determine the feasibility of using the plant AP as the ISE piping data exchange model. Shipbuilding structures will be expanding on the MariSTEP implementation that was based on a subset of the detail design data model. This will include the development of a STEP conformance class, a subset of the data model that covers a particular ship life-cycle phase or business case. Parts and part libraries are a joint effort with the ISE Electronic Commerce (EC) task to define an exchange mechanism. The critical need for such a mechanism was identified early in the MariSTEP exchange effort. ESTEP plans to exchange library part definitions, including geometric, parametric, and nongraphic attribute data. The current status, the achievements, and the future implementation plans of the ISE ESTEP are reviewed in this paper.
A Resource Center for Crosscut Initiatives: A Collaborative Effort of Avondale, Bath Iron Works, Cascade General, Electric Boat, NASSCO, Todd Pacific, and UMTRI
Authors: Davis Carol A.
Published: January 2021

The MARITECH-ASE Strategic Investment Plan recognizes the importance of addressing people and organizational issues in revitalizing the U.S. shipbuilding and ship repair industry. This recognition is reflected in the creation of the Crosscut initiative. This paper describes an effort undertaken by six shipyards and one university to design and develop a virtual resource center that addresses crosscut needs. The paper defines the scope of the project and describes the approach adopted by the project team. It reports the results of the first year of the project, and notes the products available from the project. It discusses future work to be accomplished on the project, and identifies ways in which the industry community can participate in the use and evaluation of the resource center.
Distortion Analysis of Welded Stiffeners
Authors: Vanli O. A. , Michaleris P.
Published: January 2021

This paper presents a welding distortion analysis approach for T-stiffeners with a particular emphasis on welding-induced buckling instabilities. Two-dimensional thermomechanical welding process simulations are performed to determine the residual stress and angular distortion. This critical buckling stress along with the buckling mode and bowing distortion are computed in 3-D eigenvalue and linear stress analyses. The effects of the stiffener geometry, weld sequence, weld heat input and mechanical fixturing on the occurrence of buckling and the distortion pattern are investigated.
The Project 21 Smart Product Model: A New Paradigm for Ship Design, Cost Estimation, and Production Planning
Authors: Ross Jonathan M. , McNatt Tobin R. , Hazen George
Published: January 2021

Pre-production ship design, cost estimation and production planning are traditionally carried out in U.S. shipyards through a process of extensive design work, followed by contacting multiple vendors, and coupled with production planning. This process has long been recognized as time consuming and expensive. In an effort to save time and cost, a number of synthesis models have been developed. These models are collections of trends gleaned from similar vessels. The trends, when combined, provide an estimate for initial discussions with customers, but the estimate is not sufficiently accurate for contract negotiations. An alternative is for shipyards to offer stock designs on which contract design, costing, and production planning work have already been carried out. However, most customers demand designs tailored to their particular needs. The MARITECH ASE Project 21 Smart Product Model (SPM) provides a new paradigm to meet the needs of shipyards and their customers. The SPM is initiated with a parent ship for which design, cost and production data are well known. The parent is then modified to match the customer ship's specifications. The SPM incorporates the modifications by means of an integrated set of first principles programs (e.g., FastShip for hull design) and databases (e.g., of various makes and models of main propulsion engines). The SPM provides shipyards with the speed of the synthesis models, the accuracy of the stock ship approach, and substantially improves the shipyards' competitive position.
What is Lean Ship Construction and Repair?
Authors: Liker Jeffrey K. , Lamb Thomas
Published: January 2021

The success of the Toyota Production System is well known. Toyota is the most productive and innovative automobile manufacturer in the world. Directly or indirectly they have pioneered approaches and principles such as, among many others, just in time, one-piece flow, and "andon." The Toyota Production System was the basis for "lean manufacturing." The purpose of lean manufacturing is to improve product cycle time, cost competitiveness, and quality by eliminating any waste in the manufacturing process through continuous improvement by a motivated workforce. The authors, as part of the NASSCO shipbuilding production system project, were responsible for introducing lean manufacturing to the project team and developing a "Guide to Lean Shipbuilding." This paper first discusses what lean manufacturing is, and then reports on a benchmarking visit to Japanese shipyards. Finally, a description of lean shipbuilding and its implementation is presented with case examples of lean workshops.
Lean Production in the Japanese Shipbuilding Industry?
Authors: Koenig Philip C. , Narita Hitoshi , Baba Koichi
Published: January 2021

The adoption of "lean" automobile manufacturing concepts developed by Toyota has been advocated as a means to achieve large improvements in the performance of various other industries, including shipbuilding. The basic goal of lean production is cost reduction via elimination of unnecessary operations, waiting times, and inventories. This goal is self-evidently applicable to any business environment. However, there are specific mechanisms associated with lean production, and their applicability to shipbuilding is not as clear. Has lean production been a significant influence in Japanese shipbuilding? Are Japanese shipbuilders "lean producers"? And is the lean production automobile model the appropriate approach to shipbuilding, or is some other package of best practices more applicable? We approach these questions in two ways. First, we consider the relation of lean principles to production processes in the Japanese shipbuilding industry. Then we describe two recent cases of process improvement in a Japanese shipyard and we discuss the extent to which these reflect lean principles. We propose that if lean production is considered as a general philosophy or set of goals, then the Japanese shipbuilding industry would likely rank ahead of Toyota in terms of achievement. On the other hand, considering the specifically "lean" mechanisms derived from the automobile industry experience, it appears that not all have been applicable to Japanese shipyards.
Development of Repeatable Interim Products Utilizing the Common Generic Block Concept
Authors: Storch Richard Lee , Sukapanpotharam Smith
Published: January 2021

Productive shipbuilders provide customized or made-to-order products to customers. To date, most of these "world class" companies have succeeded by developing a series of repeatable type blocks, which may be chosen and combined to form products that respond to customer needs. Type blocks have been developed as a result of long experience in customizing ships to specific needs, while maintaining a repeatable build strategy. These are, therefore, empirically based. This paper reports on the early stages of work to develop a theory and methodology for developing type blocks for shipyards that do not currently have them in place and/or lack the historical base from which to extract common blocks. The concept, called Common Generic Block, builds these using the principles of mass customization, a block complexity matrix, grouping using clustering techniques based on production attributes, and applying a threshold value as a stopping criterion for the clustering. This paper describes the general framework of the approach and provides details on the block complexity matrix, used for determining the relative similarity of products to be included in a product family.
Product-Oriented Optimum Structural Design of Double-Hull Oil Tankers
Authors: Na Seung-Soo , Karr Dale G.
Published: January 2021

A convenient interactive structural design system (ISSMID), which consists of a structural arrangement module, a scantling module, and an interface module, has been developed for the optimum design of double-hull oil tankers. The structural arrangement module defines the configuration and properties of the longitudinal, transverse, and transverse bulkhead members. The scantling module determines the scantling of the longitudinal, transverse, and transverse bulkhead members to obtain the minimum structural weight and fabrication cost. The interface module generates the data for the structural analysis (ANSYS/NASTRAN) and the CAD system (TRIBON/AUTOKON). This paper describes a new structural cost model developed by considering welding technique, welding poses, and assembly stages to manage the fabrication man-hour and process. Also, a multi-objective function method (random search method) is developed to find the minimum structural weight and fabrication cost. Several optimum structural designs are produced based on the Pareto optimal set obtained by the random search method. The design results are compared with existing ships.
Workload and Labor Resource Planning in a Large Shipyard
Authors: Meland Kenton , Spaulding Rick
Published: January 2021

Sound strategic planning at large corporations includes the development of accurate forecasts of workload and the attendant labor resources required for execution. These workload and resource plans are key to the development of the corporation's financial plans, such as revenue and income forecasts, forward pricing for future work, and the establishment of overhead rates. Additionally, these forecasts are used to develop the necessary hiring and subcontracting plans and to balance the assignment of manufacturing, construction, and engineering talent across numerous contracts. Lastly, such forecasts provide management a tool to assist in the evaluation of the impact of work scope changes. This paper provides an overview of the approach that Northrop Grumman Newport News uses to develop and manage its workload and labor resource forecasts.
Production-based Design Methodology for Shipboard Machinery Spaces
Authors: Tomassoni Carlos , Huynh Ted , Schiller Thomas
Published: January 2021

U.S. shipyards are experiencing a lack of stock designs when compared with worldclass shipyards. Shipyards in this country usually develop "unique designs" from scratch. New designs are traditionally performed by design agents, who do not account sufficiently for production requirements and constraints. This process typically results in excessive production re-engineering and/or rework. This paper presents a production-based methodology that is being developed under the National Shipbuilding Research Program/American Shipbuilding Enterprise (NSRP/ASE) Project 21, Develop and Implement World-Class U.S. Material Standards and Parametric Design Rules to Support Commercial and Naval Auxiliary Ship Construction. This methodology utilizes a zonal design approach that leverages work previously accomplished under the Shipbuilding Technology contract between Designers & Planners, Inc., and the Carderock Division of the Naval Surface Development Center in the 1994–1998 time frame. Under this contract, a collocated team with representatives of domestic and foreign shipbuilders, ship owners, vendors, and designers developed world-class engine rooms. Results of this previously conducted research were summarily reported in the Maritime Reporter. The advanced design methodology presented in this paper incorporates production requirements early in the design process that can result in significant savings in design cost and schedule, production costs, and construction cycle time. The methodology addresses how (1) machinery equipment should be grouped into functional volumes and blocks; (2) the interfaces between functional volumes and blocks and between zones should be considered; (3) producibility issues should be considered early in the design process; (4) the information should be collected and archived for use in future designs. An example is provided to show how this advanced methodology could be used to shorten design time and cost and enhance the producibility of future shipboard machinery spaces.
User-Friendly, Advanced Line Heating Automation for Accurate Plate Forming
Authors: Shin Jong Gye , Ryu Cheol Ho , Lee Jang Hyun , Kim Won Don
Published: January 2021

A fully automated line heating (LH) process includes a control system (software) and an automated machine (hardware). The software and hardware need to be developed concurrently in order to verify and maximize the efficiency of the new process. However, most shipyards have developed these separately for an automated LH process. The development also involves extensive calculations of computer-aided design, manufacturing, and engineering (CAD/CAM/CAE) information. Thus, it cannot be user friendly for technicians. The objective of this paper is to describe the entire engineering concept for the automation of LH process. Based on the object-oriented methodology, a control system and an automated machine were developed simultaneously. The main function of the control system is to provide real-time heating information to technicians or automated machines. The information includes heating location, torch speed, heating sequence, and other related information. These data are derived from CAD/CAM/CAE applications. With the calculated heating information, the machine provides automated LH tasks and collects relevant information during and after the task. The developed system shows a user-friendly capability for shipyard operators and includes advanced engineering calculations for accurate plate fabrication. A specific example was performed, in order to verify the system. Details of the applications will be described in the paper.
Scale Model Testing of a Commercial Rim-Driven Propulsor Pod
Authors: Lea Michelle , Thompson Donald , Blarcom BillVan , Eaton Jon , Friesch Juergen , Richards John
Published: January 2021

Podded propulsion is gaining more widespread use in the marine industry and is prevalent in newer cruise ships in particular. This propulsion system can provide many advantages to the ship owner that include increased propulsion efficiency, arrangement flexibility, payload, and harbor maneuverability. A new, unique podded propulsor concept is being developed that allows optimization of each element of the system. The concept comprises a ducted, multiple-blade row propulsor with a permanent magnet, radial field motor rotor mounted on the tips of the propulsor rotor blades, and the motor stator mounted within the duct of the propulsor. This concept, designated a commercial rim-driven propulsor pod (CRDP), when compared to a conventional hub-driven pod (HDP), offers improved performance in a number of areas, including equal or improved efficiency, cavitation, and hull unsteady pressures. The combination of these CRDP performance parameters allows the ship designer much greater flexibility to provide improved ship performance as compared to that of an HDP. A CRDP is being developed to power a panamax-size cruise vessel. The paper addresses the hydrodynamic performance of that CRDP design demonstrated at 1/25th scale as tested at the Hamburg Ship Model Basin, Hamburg Germany (HSVA).
Resource-Constrained Shop-Level Scheduling in a Shipyard
Authors: Prasad V. Rajendra , Graul Mike , Benjamin Perakath , Mayer Richard , Cahill Patrick D.
Published: January 2021

Ship production planning and scheduling at higher levels do not explicitly consider scheduling details at the level of individual workshops. However, the schedule of major events in ship production is collectively influenced by the actual shop-level, short-interval production schedules, which depend on resource and material availability and also on the due dates and priorities of the workloads. This necessitates development of robust, resource-constrained, shop-level scheduling systems that can support higher-level schedules in ship production. WorkShip (Knowledge Based Systems, Inc., College Station, TX) is a software tool for scheduling workload over short, regular intervals in workshops of a shipyard. It is driven by a powerful scheduling engine that is based on a generic model of resource-constrained job-shop scheduling and an efficient scheduling technique. Similar scheduling systems are being developed in other shops so that all systems can be used in tandem to support higher-level scheduling and help achieve optimal productivity for the shipyard.
Elimination of Bowing Distortion in Welded Stiffeners
Authors: Deo M. V. , Michaleris P.
Published: January 2021

Welding induces residual stresses in welded T-type stiffeners causing bowing (camber) distortion. Reducing the welding heat input or increasing the structural stiffness reduces or eliminates bowing distortion. However, where the structure geometry and weld size are fixed because of the design constraints, a transient differential heating process is effective in reducing bowing distortion. This paper presents an experimental verification and demonstration of transient differential heating for minimizing welding-induced bowing distortion in welded stiffeners. Conventional welding is carried out to demonstrate bowing distortion and establish a baseline case. Bowing distortion is eliminated using transient differential heating during welding using the same welding conditions. Residual stress measurements are taken using the blind hole drilling method, and a comparison of residual stresses for the baseline stiffener and for the stiffener with transient differential heating is presented.
Manufacture of a Prototype Advanced Permanent Magnet Motor Pod
Authors: Van Dine Piet
Published: January 2021

Podded propulsion is prevalent in the marine industry. Podded propulsion systems provide many advantages to the ship owner, including increased propulsion efficiency and reduced construction cost. To evaluate the potential of a new pod configuration, a prototype machine was constructed and tested. This prototype machine was mainly constructed of composite parts. The propeller, housings, structural blading, motor canning, and fairings were constructed of composite materials. Composite materials were chosen as a cost saving, schedule reduction, performance enhancement, and as a technology demonstration. This paper will review the unit construction, and test results, focusing on the lessons learned for the composite part manufacture.
Productivity Improvement at the SENESCO Shipyard
Authors: Gebhardt Laurence P. , Jarvis Robert G.
Published: January 2021

This paper examines how SENESCO, a small business shipyard, perceives and practices productivity theory within a company mission and management framework that balances safety, production, quality, and responsibility. The paper discusses the various ways in which productivity is achieved and improved at the SENESCO shipyard. Themes in this paper are consistent with goals and objectives of the National Shipbuilding Research Program (NSRP) Crosscut Initiatives Panel. Concepts in this paper could be adapted or adopted by other small to mid-sized shipyards or smaller units of larger shipyards. Quantitative evidence of our productivity improvement will be shared in a subsequent paper.
Limited-Temperature Compound Cycle Hybrid Piston-Turbine Engine
Authors: Pien Pao Chi
Published: January 2021

A new hybrid piston-turbine engine is presented comprised of a power turbine driven by exhaust gas of a new 4SDI engine utilizing a new piston-cam assembly powertrain and operating on a limited-temperature compound cycle. The limited-temperature compound cycle has a prolonged combustion process under a limited combustion temperature. By limiting the combustion temperature, NOx formation is avoided; by prolonging combustion, more complete combustion occurs, minimizing particulates and other noxious emissions. The power turbine extends the expansion process started in the 4SDI engine to reach the atmospheric pressure for achieving high fuel economy. The piston-cam powertrain, which features reciprocating pistons that oscillate cam followers, through a rocking yoke mechanism to rotate a power output camshaft, significantly reduces engine friction losses to achieve high mechanical efficiency. The new hybrid piston-turbine engine, which can be developed with existing technologies, has particularly beneficial application to ship propulsion.
Ship Product Modeling
Authors: Whitfield R. I. , Duffy A. H. B. , Wu Z.
Published: January 2021

This paper is a fundamental review of ship product modeling techniques with a focus on determining the state of the art, to identify any shortcomings and propose future directions. The review addresses ship product data representations, product modeling techniques and integration issues, and life phase issues. The most significant development has been the construction of the ship Standard for the Exchange of Product Data (STEP) application protocols. However, difficulty has been observed with respect to the general uptake of the standards, in particular with the application to legacy systems, often resulting in embellishments to the standards and limiting the ability to further exchange the product data. The EXPRESS modeling language is increasingly being superseded by the extensible mark-up language (XML) as a method to map the STEP data, due to its wider support throughout the information technology industry and its more obvious structure and hierarchy. The associated XML files are, however, larger than those produced using the EXPRESS language and make further demands on the already considerable storage required for the ship product model. Seamless integration between legacy applications appears to be difficult to achieve using the current technologies, which often rely on manual interaction for the translation of files. The paper concludes with a discussion of future directions that aim to either solve or alleviate these issues.
Contracting and Project Management of Complex Equipment
Authors: Jones R. Brian
Published: January 2021

As the sole builder of nuclear aircraft carriers for the U.S. Navy, Northrop Grumman Newport News relies heavily on the 900-metric-ton Goliath gantry crane to assembly the 162 critical "super lifts" that compose a completed carrier structure. Prior to 1999, it was apparent that the 25-year-old crane needed a major overhaul. When the project was funded in 1999, Newport News assembled a team composed of engineering, maintenance, and operations to perform detailed design, develop the specification, manage the bidding process, and manage the project. Capital constraints on the project required the team to collaborate with suppliers to move portions of the project scope back to Newport News, reducing risk for the suppliers and reducing capital costs for Newport News. This team/collaboration approach proved successful as the project was completed on schedule and within budget.
An Efficient Algorithm for Measurement and Comparison of Large-Scale Hull Pieces in the Line-Heating Process
Authors: Shin Jong Gye , Lee Jong-Moo , Nam Jong-Ho
Published: January 2021

When a curved plate is subject to deformation during the forming operation in the shipbuilding process, the deformed shape is repeatedly measured and compared to the designed shape. Because there are a number of large curved plates of different sizes and shapes, efficient measuring and comparison processes are essential to examine the quality of deformed plates rapidly and accurately, and consequently to enhance productivity in the whole manufacturing process. Currently, deformed plates are measured and examined using traditional templates. This practice is not only time-consuming but prone to human errors. Therefore, a new approach to streamlining the measurement and comparison processes needs to be proposed. In this paper, an efficient algorithm for the measurement and comparison of curved plates is introduced. A full-scale measurement machine with its control software is constructed, and an algorithm for the comparison system is implemented. The integrated algorithm is verified with many curved pieces of different sizes and shapes.
Remedy for Misalignment of Bilobe Cargo Tanks in Liquefied Petroleum Gas Carriers
Authors: Senjanovi Ivo , Rudan Smiljko , Ljustina Ana Maria
Published: January 2021

The work describes independent tanks of different shapes, which are further subdivided into A, B, and C types related to design pressure. Special attention is paid to the remedy for misalignment resulting from manufacturing difficulties in a 3,000-m3 bilobe cargo tank of a 8,350-m3 liquefied petroleum gas (LPG) carrier. Namely, some eccentricity in the Y joint of tank shells and longitudinal bulkhead usually remains during fabrication, which causes additional stress concentration. This problem is first considered analytically and then numerically. A complete and reliable solution is achieved by a three-dimensional finite element method analysis of a tank segment between two vacuum rings. Reinforcement of the Y joint by a set of knees and bars, according to the value of the shell's eccentricity, is recommended in order to reduce the stress level below the allowable value. The obtained results are presented in a practical diagram for general use. Following the given instructions, the cargo tanks of the considered LPG are reinforced and submitted to the hydraulic test with water pressure 50% higher than the design pressure. Having passed this test successfully, the approval of the relevant classification society is obtained.
Discrete Event Simulation: An Efficient Tool to Assist Shipyard Investment and Production Planning
Authors: Krause Matthias , Roland Frank , Steinhauer Dirk , Heinemann Maximilian
Published: January 2021

The complexity both of the product ship and the shipbuilding process make planning tasks in long, medium, and short terms difficult and lead to serious uncertainties. Discrete event simulation can be used to test and evaluate different scenarios in investment planning, scheduling, and resource planning. Using a virtual shipyard environment, the cost to find optimum solutions and the risk related to wrong decisions in the real world can be drastically reduced. However, due to the special skills and efforts usually needed to develop simulation models, the practical application of production flow simulation in shipyards is still rather limited. Object-oriented simulation tool sets specially developed for shipbuilding needs provide the chance to drastically reduce these efforts. Object libraries containing general and shipbuilding specific components with defined interfaces shorten the time needed for development of models for similar purposes. Furthermore, the integration of discrete event simulation models for certain shipyard facilities into a holistic model of the entire enterprise is made possible by using a tool set. Because of costs, some shipyards shy away from investing in simulation techniques. Networking activities and joint projects on simulation issues help to overcome those obstacles. German Flensburger Schiffbaugesellschaft already uses a simulation tool set successfully and actively cooperates with universities and other shipyards, while Center of Maritime Technologies has gathered experience in this field during participation in several simulation projects with other shipyards, for example, Jos. L. Meyer and Aker Ostsee. The article revues practical applications of simulation, gives an impression of how object-oriented simulation tool libraries can be structured, and outlines collaboration possibilities for making simulation applications affordable.
Dimensional Measurement of a Composite Ship Hull Using Coherent Laser Radar Yielding Submillimeter Results
Authors: Hand Steven D. , Ober David B. , Bond Bryan A. , Devine Edward A.
Published: January 2021

The use and result of coherent laser radar as a noncontact method for the dimensional measurement of a ship hull is described. The hull, keel, and deck of a halfscale notional glass-reinforced plastic (fiberglass) composite hull test specimen are measured to submillimeter accuracy and then compared to the computer-aided design (CAD) model for conformance validation. Positives and negatives of this technology are the subject of this paper and include the high accuracy potential of the coherent laser radar, the minimal manpower requirements needed to achieve accurate results, and the limitation of the equipment's digital focal length and its effects on setup and data acquisition.
A Software Tool for Disposal of Obsolete Vessels
Authors: Ahluwalia Rashpal S. , Govindarajulu Sriram
Published: January 2021

This paper describes a prototype software tool for the dismantling of obsolete vessels (DOVE). It is a Web-based tool, developed using the .NET architecture with MS SQL Server as the database. It can be used by the Maritime Administration (MARAD), Navy, or a ship-scrapping company to estimate ship-dismantling costs, to view inventory of surplus vessels, to view construction details of a vessel, and to determine the amount of petroleum products on board. The DOVE database also lists US-based ship-dismantling sites, towing companies, vessel builders, and metal-cutting and decontamination technologies.