bluuebunny/crossref_metadata_2025 huggingface dataset:
Marine Propulsion Shafting: A Study of Whirling Vibrations
Authors: Legaz María José , Amat Sergio , Busquier Sonia
Published: January 2021

Whirling vibration is an important part of the calculations of the design of a marine shaft. In fact, all classification societies require a propulsion shafting whirling vibration calculation giving the range of critical speeds, i.e., free whirling vibration calculation. However, whirling vibration is a source of fatigue failure of the bracket and aft stern tube bearings, destruction of high-speed shafts with universal joints, noise, and hull vibrations. There are numerous uncertainties in the calculation of whirling vibration, namely, in the shafting system modeling and in the determination of excitement and damping forces. Moreover, whirling vibration calculation mathematics is much more complex than torsional or axial calculations. The marine propulsion shaft can be studied as a selfsustained vibration system, which can be modeled using the Van der Pol equation. In this document, a new way to solve the Van der pol equation is presented. The proposed method, based on a variational approach without local minima extra to the solution, converges for whatever initial point and parameter in the Van der Pol equation.
Large Two-Stroke Marine Diesel Engine Operation with a High-Pressure SCR System in Heavy Weather Conditions
Authors: Foteinos Michael I. , Christofilis George I. , Kyrtatos Nikolaos P.
Published: January 2021

The transient performance of a direct-drive large two-stroke marine diesel engine, installed in a vessel operating in a seaway with heavy weather, is investigated via simulation. The main engine of the ship is equipped with a selective catalytic reduction (SCR) aftertreatment system for compliance with the latest International Maritime Organization (IMO) rules for NOx reduction, IMO Tier III. Because of limitations of exhaust gas temperature at the inlet of SCR systems and the low temperature exhaust gases produced by marine diesel engines, in marine applications, the SCR system is installed on the high-pressure side of the turbine. When a ship sails in heavy weather, it experiences a resistance increase, wave-induced motions, and a time-varying flow field in the propeller, induced by ship motions. This results in a fluctuation of the propeller torque demand and, thus, a fluctuation in engine power and exhaust gas temperature, which can affect engine and SCR performance. To investigate this phenomenon and take into account the engine–propeller interaction, the entire propulsion plant was modeled, namely, the slow-speed diesel propulsion engine, the high-pressure SCR system, the directly driven propeller, and the ship’s hull. To simulate the transient propeller torque demand, a propeller model was used, and torque variations due to ship motions were taken into account. Ship motions in waves and wave-added resistance were calculated for regular and irregular waves using a 3D panel code. The coupled model was validated against available measured data from a shipboard propulsion system in good weather conditions. The model was then used to simulate the behavior of a Tier III marine propulsion plant during acceleration from low to medium load, in the presence of regular and irregular waves. The effect of the time-varying propeller demand on the engine and the SCR system was investigated.

Introduction

The effect of waves on a marine propulsion system is a complex phenomenon involving interactions between different subsystems of the propulsion plant, i.e., the prime mover, the propeller, and the ship’s hull. Ships sailing in heavy weather conditions experience a resistance increase, wave-induced motions, and a time-varying flow field in the propeller. This leads to a fluctuation of the propeller torque demand which results in a fluctuation in engine-produced power and exhaust gas temperature.
Experimental and Theoretical Study of the Effect of Hull Roughness on Ship Resistance
Authors: Song Soonseok , Dai Saishuai , Demirel Yigit Kemal , Atlar Mehmet , Day Sandy , Turan Osman
Published: January 2021

Hull roughness increases ship frictional resistance and, thus, results in economic and environmental penalties. Its effect has been prevalently predicted using the similarity law scaling procedure. However, this method has not yet been validated with experimental data using a model ship. This study presents an experimental investigation into the effect of roughness on ship resistance and provides a validation of the similarity law scaling, by using tank testing of a flat plate and a model ship. Both the plate and the ship were tested in smooth and rough surface conditions, respectively. For the rough surface conditions, sand grit (aluminum oxide abrasive powder) was applied on the surfaces of the flat plate and the ship model. The roughness functions of the rough surface were derived by using the results obtained from the flat plate tests. Using the roughness function and the flat plate towing test, frictional resistance was extrapolated to the length of the model ship following the similarity law scaling procedure. The total resistance of the rough ship model was first predicted using the extrapolated frictional resistance and the result of the smooth ship model, and then compared with the results from the rough ship model. The predicted total resistance coefficients for the rough ship model showed a good agreement with the measured total resistance coefficient of the rough ship model, thus proving the validity of using Granville’s similarity law scaling to extrapolate the roughness effect on ship resistance.
Ship Traffic Flow Prediction Based on Fractional Order Gradient Descent with Momentum for RBF Neural Network
Authors: Han Xue
Published: January 2021

To prevent the maritime traffic accidents and make scientific decision, scientific and accurate prediction of the traffic flow is useful, which has often been made by neural network. The weight updating methods have played an important role in improving the performance of neural networks. To ameliorate the oscillating phenomenon in training radial basis function (RBF) neural network, a fractional order gradient descent (GD) with momentum method for updating the weights of RBF neural network (FOGDM-RBF) is proposed. Its convergence is proved. The new algorithm is used to predict vessel traffic flow at Xiamen Port. It performs stable and converges to zero as the iteration increases. The results verify the theoretical results of the proposed algorithm such as its monotonicity and convergence. The descending curve of error values by fractional order GDM is smoother than the GD and GDM method. Error analysis shows that the algorithm can effectively accelerate the convergence speed of the GD method and improve its performance with high accuracy and validity. The influence of fractional order, number of hidden layer neurons, tide peak hours, and ship size is analyzed and compared.

1. Introduction

As the world shipping becomes more and more busy, the large ship traffic flow leads to frequent maritime traffic accidents, resulting in huge economic losses. Ship traffic flow is a basic system in marine traffic engineering and an important index to measure the construction of marine traffic infrastructure. Its prediction results can provide basis for formulating scientific Port management planning and ship navigation management. Therefore, to ensure the accuracy and rationality of ship traffic flow forecasting is of great significance for improving port infrastructure construction and formulating scientific port management strategies. Many advanced artificial intelligence optimization algorithms have been used for ship traffic flow forecasting, such as artificial neural network (Zhai 2013; Zhang 2015). Neural network can deal with complex nonlinear problems and has achieved some results. However, the neural network itself has some shortcomings, such as slow learning speed, easy to fall into the local extremum, learning and memory instability, etc.
Experimental and Numerical Investigation of Green Water Occurrence for KRISO Container Ship
Authors: Babu Kudupudi Ravindra , Nelli Sri Vinay Krishna Rayudu , Bhattacharyya Anirban , Datta Ranadev
Published: January 2021

The occurrence of green water on the deck of Korea Research Institute of Ships & Ocean Engineering (KRISO) container ship is investigated using model test experiments and a fully coupled impulse response function (IRF)–computational fluid dynamics (CFD)–based numerical approach. In the experimental study, green water pressure over the deck and superstructure is investigated for different regular head wave conditions (wavelength/ship length ratio: .8–1.5) and vessel speeds (Froude number: .055–.166). The impact pressure on the deck is found to be highest at a wavelength/ ship length ratio of 1.2 and increases drastically with the increase in Froude number. The variation of green water pressure with wave steepness is linear for points on the forward deck and quadratic for the superstructure. In the second part, a coupled IRF-CFD–based numerical method is developed in which the global hydrodynamic forces such as radiation–diffraction and Froude–Krylov force are computed using a potential flow solver, whereas the local pressure due to the shipping water impact is computed using CFD and added as an external force. Comparisons of vessel motions and green water pressures with experiments indicate that the coupled IRF-CFD method can be a robust and efficient tool to predict shipping water loads on ships.

Introduction

The prediction of green water shipped on the deck and the resulting impact on ships and offshore structures have been an important research topic in the last couple of decades because it is directly related to the safety of the structure at sea. Historically, shipping of water on the deck had caused many serious damages to the bow and superstructure, and some of them have even capsized; e.g., the Schiehallion Floating Production Storage and Offloading (FPSO) was damaged severely in November 1998 because of steep waves. These incidents resulted in considerable research on this topic in the past two decades. The primary focus has been on the understanding of critical aspects and the accurate prediction of green water loading which requires proper modeling of green water occurrence. Also, accurate calculation of the green water loads on the deck and superstructure is very important for structural design load calculation. However, this is a nontrivial task because it depends on many physical and geometrical factors such as wave steepness, the wavelength- to-ship length ratio, hull shape around the bow region, and vessel speed. Hence, efforts have been made to develop suitable numerical models that may consider most of these aspects under necessary underlying assumptions.
Steady and Unsteady Hydrodynamic Loads on the Azimuth Bearing of a POD during a Crash-Stop Maneuver
Authors: Neitzel-Petersen Jan Clemens , Stutz Sophie Juliane , Abdel-Maksoud Moustafa
Published: January 2021

The crash-stop maneuver of a ship equipped with two pods produces the largest loads that the structure and azimuth bearing can possibly experience. For design purposes, a sufficiently fast and accurate determination of the loads is thus critically important. This study examines load estimation during crash-stop maneuvers based on model tests and numerical methods. Forces and moments are compared to determine the influence of different control parameters (azimuth rate, propeller number of revolution, etc.). In addition, the results of numerical simulations carried out in model- and full-scale are used to analyze the influence of the Reynolds number on the flow behavior. Results show a significant influence of the azimuth rate on the maximum forces and moments. The numerical calculations indicate a strong dependency of the flow stall behavior on the azimuth rate. The dynamic stall effect on the profile-shaped parts, such as the pod strut, is shifted to a larger angle of attack compared with a steady angular position. This phenomenon is also observed during the model tests. The full-scale simulations show up to a 23% increase of the forces compared with the model-scale simulations. Thus, a detailed and careful handling of the results considered in the design process is required for the load estimation.
Towing Tank Model Tests for Propulsive Performance Analysis of a Waterjet-Propelled Amphibious Vehicle
Authors: Seo Jeonghwa , Jeong Hoe-Seong , Rhee Shin Hyung , Chang Kyogun
Published: January 2021

The present study concerns a series of model tests in a towing tank on waterjet propulsive performance. The test model was an armored vehicle consisting of a box-shaped hull, two waterjets, a bow flap, and a trim tab. As per the powering prediction procedure of high-speed vessels, resistance tests, waterjet system tests, and self-propulsion tests were performed. The Froude number based on the characteristic length and advance speed for the model tests ranged from .981 to 1.178. Bollard pull tests were also conducted to investigate the interaction between the hull and two installed waterjets and to validate the flow rate estimation. In the self-propulsion condition, the dry transom and nozzle end modification changed the interaction efficiency. The waterjet reduced the vehicle trim in the self-propulsion condition, owing to the nozzle exit flow onto the trim tab.

Introduction

Waterjet propulsion systems have been widely used in marine vessels, thanks to its advantages of low cavitation in high loading, safe operation in shallow water, and good maneuverability at low advance speed (Allison 1993). However, the propulsive performance of waterjets is a complicated problem and hard to analyze. The extrapolation method for the powering performance prediction of waterjet-propelled vessel is suggested by the International Towing Tank Conference (ITTC) (ITTC 2011), but it is less comprehensive than that of the conventional ship with screw propellers (ITTC 2017a), as test institutions for waterjet-propelled vessels are scarce and test methodology is not standardized (Altosole et al. 2012).
Solving 2-D Slamming Problems by an Improved Higher-Order Moving Particle Semi-Implicit Method
Authors: Zha Ruosi , Peng Heather , Qiu Wei
Published: January 2021

A higher-order moving particle semi-implicit (MPS) method was further developed to solve 2-D water entry problems. To overcome the inconsistency in the original MPS methods, a pressure gradient correction was implemented to guarantee the first-order consistency of the gradient. The corrective matrix was modified by using the derivative of the kernel function. A particle shifting technique was also applied to improve the numerical stability. Validation studies were carried out for water entry of a rigid wedge with the tilting angles of 0, 10, and 20, and two rigid ship sections. Convergence studies were conducted on domain size, particle spacing, and time step. A particle convergence index method was proposed to evaluate numerical uncertainties in the improved MPS method. Uncertainties in numerical solutions due to spatial discretization were calculated. The predicted impact pressures and forces by the present method are in good agreement with experimental data.

Introduction

Slamming can cause local structural deformation and damages. It is important to solve highly nonlinear water-entry problems involving breaking free surfaces. Many studies on the impact of pressures/ loads during water entry or slamming have been performed using experiments, analytical solutions, and numerical simulations. Extensive drop tests have been conducted. For example, Bisplinghoff and Doherty (1952) carried out a series of experiments for free-fall wedges. Because ship motions in waves can lead to asymmetric water entry, wedges with different tilt angles were tested by Barjasteh et al. (2016). A more detailed review of studies based on theoretical, potential-flow, and computational fluid dynamics (CFD) methods is presented in the work of Peng and Qiu (2018).
A Holistic Approach to Ship Design: Tools and Applications
Authors: Papanikolaou Apostolos , Harries Stefan , Hooijmans Patrick , Marzi Jochen , Le Néna Romain , Torben Sverre , Yrjänäinen Antti , Boden Brigitte
Published: January 2021

The present article introduces a holistic approach to ship design, as it is being developed in the Horizon 2020 EU project HOLISHIP (www.holiship.eu). The project deals with the development of design and virtual prototyping simulation platforms, which integrate software tools for all major ship design disciplines and optimization objectives, namely, building and operational cost, energy efficiency, safety, environmental footprint, and life cycle cost/impact assessment. It enables the seamless mathematical multi-objective optimization of ship design with governing design constraints and the exploration of the huge design space by parametric modeling of the ship design system and its components. The article outlines the integration of the essential software tools into the software platform and demonstrates the functionality and benefits of the HOLISHIP approach by brief presentations of typical case studies.

Introduction

The pattern of seaborne trade and goods transportation is changing, and so do the vessels of transportation. They need to adapt to changes in customer and market requirements, changes in cargo types and volumes, and new legislation for the safety of ships and the protection of the marine/aerial environment. Increased requirements for energy efficiency and the control of GHG emissions and the inherent uncertainties regarding fuel cost and future types of marine fuels pose extra challenges. This calls for significant advances in the approach to ship design and operation to meet continuously changing requirements over ship’s life cycle by holistic, efficient, and easy-to-use design procedures and software systems.
Accuracy Control for U.S. Shipyards
Authors: Storch Richard Lee , Gribskov Jon R.
Published: January 2021

Research conducted by University of Washington personnel at Tacoma Boatbuilding Company (TBC) has provided a basis for any U.S. shipyard to initiate and operate an accuracy control system. This paper discusses the steps necessary for initiation of such a system and then outlines, in case study format, the practical aspects of accuracy control planning, execution (measuring) and evaluation (analysis). Examples of vital point selection, planning sheets, check sheets, normal distributions of variation determination and control chart development are presented. A discussion of the long-term value of an accuracy control system is also included. The results presented are based on actual on-site research at TBC, involving the construction of the stern section of Hulls 1 and 2 of the U.S. Navy T-AGOS vessels.
A Practical Approach to Repair Innovation
Authors: Korsse A. , Nijman Jac.
Published: January 2021

This paper presents a practical approach to repair innovation made by the Amsterdam Drydock Company in The Netherlands. In this approach special attention has been given to several time-saving methods and to making optimal use of available manpower. The layout of the necessary workshops also had to be studied carefully and the existing premises had to be restructed in the most practical way. A $25 million investment program was carried out with the aim of creating a repair yard for the 1980's and the years beyond.
CAD/CAM Applications to Mass Properties
Authors: McNeal J.C. , Nilsen H.G. , Mathews J.J.
Published: January 2021

In the shipbuilding industry, it is relatively common knowledge that CAD/CAM (Computer Aided Design/ Computer Aided Manufacturing) systems can generate accurate and consistent drawings. These drawings can then be used for production support lofting, parts generation, reference material and so forth. However, one of the most significant advantages of utilizing a CAD/CAM system is not so commonly known: the development of a design database. While conventional computer systems generate, store and analyze numerical or textual databases or both, CAD/CAM systems generate, store and analyze data bases of graphics. This paper illustrates methods which optimize use of a graphic data base, focusing on the application of CAD/CAM analytical capabilities to mass properties analyses (as practiced in naval ship design). These methods are results of combining CAD/CAM technology with existing systems and knowledge to achieve cost-effective, technically superior, more accurate methods of performing engineering tasks. Accordingly, methodology, actual productivity comparisons and other related applications are presented.
Designing for Productivity: A Standardized Coal-Fired Propulsion Plant
Authors: Yuengling D. J. , Pakula T. J.
Published: January 2021

A design for a 26 000-shp standardized coal-fired steam turbine propulsion plant using product work breakdown structure (PWBS) or group technology techniques was developed for the Maritime Administration. The purpose of the design was to provide a design package for a production approach which could reduce machinery outfitting cost and time by one third. Emphasis was placed on piping within the main machinery space. In the concept and preliminary design phases, the machinery box was developed to fit within the hull lines of an 80 000, 144 000, and 180 000-dwt collier. Propeller size, shaft line, and rpm were defined; the steam cycle was selected; and initial machinery arrangements were developed for both a dual boiler and a single boiler plant. During contract design, machinery specifications, schematic diagrams, arrangements, and procurement specifications were developed. In production design, standards were developed, schematic diagrams were revised, and piping diagrammatic arrangements, composites, material lists, and purchase orders for components were prepared. A production philosophy and build strategy also were developed. This effort made use of the PWBS approach presented in the MarAd National Shipbuilding Research Program reports[1–5]3
Construction Cost Optimization of Buoyant Steel Structures
Authors: Baird David , Winkle Ian E.
Published: January 2021

The need for a rational means of comparing structures in terms of not only weight but also construction time and cost is established. This paper describes a database and methodology used at Glasgow University which is proposed as a general method for cost estimation and optimization. Examples are given to demonstrate the use and capabilities of the proposed method.
Engineering Management for Zone Construction of Ships
Authors: Lamb Thomas
Published: January 2021

Zone construction has been proposed as the way for the U.S. shipbuilding industry to improve its productivity and survive the current hard times. Obviously as the production requirements for zone construction are different from traditional ship construction, so are the engineering requirements. While production could perform zone construction from traditionally prepared engineering, it would do so inefficiently and after waiting a long time for most of the engineering to be completed before they could start, thus defeating one of the goals of zone construction. The production department in a shipyard changing to zone construction will probably reorganize into major zone sections. To obtain maximum benefits from zone construction it is necessary for the engineering department to be like-organized and managed. The paper therefore discusses engineering aspects that are influenced by the change to zone construction
Northern European Craft Training: A Trip Report
Authors: Vickers Paul William
Published: January 2021

The Education and Training Panel of the Ship Production Committee conducts research on training methods and techniques and develops new training methods. As part of this effort, the panel conducted an on-site inspection and evaluation of craft training programs in Europe. In June 1985, a four-person project team traveled to Northern Europe to meet with shipbuilding trainers and educators. This paper presents highlights of that trip. Discussed here are apprentice training programs of the United Kingdom and the Federal Republic of Germany, and adult training in Scandinavia.
Islands of Automation in Shipbuilding
Authors: Bellonzi Robert J.
Published: January 2021

The use of system-independent automation technologies, referred to as "islands of automation," is discussed as a way to improve shipbuilding productivity. The author uses the production automation program at Bath Iron Works as an example. Low-technology, labor-intensive tasks are targeted for implementation of automation technologies. This paper describes a five-point plan to ensure program success: use proven technologies; limit financial risk of the program; allow for future technology improvements; develop a reasonable project schedule based on results-oriented goals; and establish a structured hierarchy of all work groups involved.
The Nesting and Marking of Ship Parts Cut from Steel Plate
Authors: Hooper Harry
Published: January 2021

The methods presently used by U.S. shipbuilders for preparing, nesting and marking plate parts are discussed. The use of existing computer technology is explored as a means for improving these operations by conserving plate and reducing operating costs. Appendices are included which list the advantages and disadvantages of both the oxy-flame and plasma cutting processes, the use of special sized plate in hull construction, and the basic features of a computerized parts nesting system.
Use of Standard Task Blocks to Simplify the Ship Production Process
Authors: Wade Michael
Published: January 2021

A system of production planning with a built-in capability to monitor performance at all levels of the shipbuilding process is the focus of this paper. The heart of this system—the standardized task block—incorporates individual and comprehensive work packages from fabrication through project completion. The logic, procedure, and economy of the method are discussed with particular emphasis on the modular/zone concept of ship construction, which provides the basis for establishing the task block matrices.
Producibility as a Design Factor in Naval Ships
Authors: Bosworth Michael L. , Graham Clark
Published: January 2021

There are many producibility concepts which affect the characteristics of a naval ship. These concepts must be addressed during the early phases of the ship design process while the ship is still flexible. Since these producibility concepts may affect ship performance and technical risk, as well as ship characteristics and cost, a rigorous tradeoff analysis is required. This paper provides examples of producibility concepts which should be addressed during the ship design process. An evaluation procedure is presented to assist in the gathering and the organizing of information required for an objective tradeoff analysis. The ship synthesis model "ASSET" is utilized as the principal design tool to determine ship impact and the cost of producibility concepts. One of the primary recommendations of the authors is that the Navy increase the visibility of producibility as a design factor in naval ships by developing rigorous evaluation tools, cataloging producibility concepts for considerations in future designs, and establishing an advocate for ship producibility within the design organization.
Shipyard Transfer Systems
Authors: Salzer John Richard
Published: January 2021

Modern shipyard layout concepts tend toward providing a single facility for launching or drydocking vessels and depend upon the use of transfer systems to move ships between that facility and the shore berths where they were constructed or where they will be or were repaired. Considerable ingenuity has been applied to solving the problems of ship transfer. This paper describes and categorizes some of these solutions and explores some of the systems which may not have seen extensive use but which have been considered and which may hold promise. Further, it explores the merits and shortcoming of the various systems and their interfaces with the various types of drydock/launcher.
The Overtonnage of Large Tankers: Status and Prospects
Authors: Hattori Katsuhiko , Perakis A. N.
Published: January 2021

The surplus tonnage in the tanker market has been steadily increasing each year since the second oil crisis, with very large and ultra large crude carriers (VLCC's and ULCC's) being hit the hardest. As a result of these constant increases, the market has been very depressed since 1981, with excess tonnage of more than 100 million dwt. After more than four years of such an overwhelming volume of excess tonnage, the overall situation remains unchanged, despite the massive demolitions underway. In spite of this surplus tonnage, wide spot rate fluctuations were registered in 1984, under the growing intensity of the Iran-Iraq conflict, involving attacks on tankers. Still, some contend that there is no alternative but demolition as the mechanism for recovery of the tanker market. This paper makes an analytical assessment of the current and future trends of this huge surplus tonnage of large tankers on the basis of the available data.. An estimation of future trends is also made, using standard system dynamics modeling techniques.
Expanded Planning Yard Concept and Configuration Accounting, or Improving Navy Ship Engineering
Authors: Karn A. R. , Runnerstrom E.
Published: January 2021

For several years the Navy has been systematically analyzing problems with its ship engineering and improving its organization and processes for ship engineering. This paper briefly discusses the Navy organization for ship engineering and some of the major initiatives to improve ship engineering. These initiatives have led to an expanded role for the planning yard in supporting, maintaining, and modernizing Navy ships. The paper focuses on the two primary functions of the planning yard: ship alteration engineering and ship configuration identification.
Evaluation of Wet Blasting for Ship Application
Authors: Appleman Bernard R.
Published: January 2021

This paper presents the results of a field investigation of equipment and technology for wet abrasive blasting as a technique for preparation of structural steel for painting. Ten different commercially available wet blasting units were selected for field evaluation. The units selected included the following generic types: air abrasive wet blasting (addition of water at the nozzle to conventional dry blasting equipment); air/water/abrasive slurry blasting (mixing of water with the abrasive at a control unit upstream of the nozzle); pressurized water abrasive blasting (abrasive added to high-or low-pressure water jetting stream); and ultrahigh-pressure water jetting [20000 psi (137.9 MPa) or greater]. These evaluations were conducted on steel surfaces, typically encountered in shipyards and industrial environments, including rusted and pitted steel, milscale steel, and painted steel. The investigation considered factors such as the cleaning rates, abrasive and water consumption, operator thrust, portability, safety procedures required, use of inhibitors, and overall practicability and reliability. The paper discusses each of these factors and provides a tabulation of advantages and disadvantages for each unit observed.
Technical Collaboration Between Mitsubishi Heavy Industries and Todd Shipyards
Authors: Thorell Lennart M. , Watanabe Toshio
Published: January 2021

In June 1984, Todd Shipyards Corporation, U.S.A. (Todd) and Mitsubishi Heavy Industries, Ltd., Japan (MHI) concluded an agreement to transfer merchant ship construction and conversion technology between the two corporations. To date, the program has been unique. MHI opened its Kobe Shipyard to Todd's personnel for first-hand observation of its modernized facilities and equipment, its production methodology, and its state-of-the-art shipbuilding technology. This paper:explains how this collaborative agreement was reached, from the initial proposal by MHI through acceptance by Todd,describes the agreement between both parties, andsummarizes the productivity improvements implemented and projected for future implementation by Todd's Los Angeles Division.
Decentralization—The Management Key to Effective Accuracy Control
Authors: Upham Tamara S. , Crawford W. Mark
Published: January 2021

This paper presents the organizational structure, methods, and results of National Steel and Shipbuilding Company's (NASSCO) efforts to decentralize the responsibility of statistical accuracy control from a central Accuracy Control Department to the hourly production workforce. It includes an accounting of the problems and successes encountered during implementation. The results are both quantitative and qualitative in form, including methods for measuring reductions in rework. During this study, workteams were established in the Hull Fabrication Shop. A three phase methodology was used to introduce the workteams to statistical methods for improving the dimensional accuracy of their products.
The 1983 CAD/CAM Survey: Why It’s Still Relevant, What It Said
Authors: Diesslin Richard L.
Published: January 2021

The response to the CAD/CAM shipbuilding industry survey of 1983 was quite comprehensive. The survey included an invaluable cross section of shipyards and design agencies of all sizes, levels of sophistication, and type of production. It remains the most significant study of its kind in recent years. Eighteen shipyards and four design agencies participated. In addition, nine visits were made, eight to shipyards and one to a design agency. This paper summarizes the findings of the CAD/CAM survey, which studied the application of computer technologies (CT's) to manufacturing in the U.S. ship building industry. Six major CT areas are evaluated across 79 specific shipyard functions; then the software in use is evaluated based on user experiences. Finally, computer technologies are evaluated based on their qualitative benefits and problems. Highlights from the shipyard visits are outlined, voids in the shipbuilding industry's application of CT are presented, and recommendations and conclusions are cited based on survey findings.
An Integrated Procedure for Hull Design and Production
Authors: Luca Renzo Oi
Published: January 2021

The effective integration of hull design and production procedures is achieved by applying a comprehensive modeling technique that recognizes both the stages in the design process and also the structural component generation requirements. This paper describes an operational CAD/CAM system that is fully integrated from preliminary design through production. Some features discussed are ship-oriented model representations, common descriptive techniques, multi-user model access, and general graphic technology.
The Establishment of Shipbuilding Construction Tolerances
Authors: Butler J. D. , Warren T. R.
Published: January 2021

Predictable and economically achievable construction tolerances are a prerequisite for the establishment of effective shipbuilding procedures, as unproductive rework and on-the-job fit-ups are the alternative. This paper reviews the factors to be considered in the development of tolerances and suggests the use of variation-merging equations and variation simulation as techniques that can be used to formulate a practical system of tolerances.
Laser Line Heating
Authors: Scully Kevin
Published: January 2021

Many shipyards now employ line-heating processes to form metal by controlled heating and cooling. The benefits of line-heat forming include improved accuracy and productivity. The current line-heating method utilizes an oxyacetylene torch as the heat input. A new forming technique that uses a high-power laser as the heat source is being researched. The feasibility of forming mild-and high-strength steels with a laser heat input is reviewed. The primary incentives for using a laser are the capability to accurately control the forming process; the capability to minimize the material degradation; the capability to form high-strength steels; and the increased compatibility with other advanced manufacturing systems. In summary, by manipulating the laser power, laser beam diameter, and plate travel speed, one may form metal plates to a predetermined shape in a repeatable manner.
Reduced Fillet Weld Sizes for Naval Ships
Authors: Gaines Ed
Published: January 2021

Recently, Ingalls Shipbuilding Division of Litton updated its fillet weld design practices for naval ship construction. This task was part of a continuing effort to improve accuracy control by decreasing weld-caused distortion. Recent material properties and a more rigorous engineering analysis were used to reduce the required fillet sizes by about 25 percent for steel and about 50 percent for aluminum. The analysis method was developed for the Navy at Newport News Shipbuilding during the 1970's. Intermittent weld tables were developed and, where utilized, proved to be a very cost-effective distortion control measure. Reducing the amount of weld reduces distortion and economically improves accuracy control. Fabrications costs were significantly reduced. This paper reviews the methods and properties used to develop and implement the new weld tables. The benefits to distortion control and construction costs are also discussed.
Thermal Spraying in the U.S. Navy
Authors: Vittori Stephen
Published: January 2021

Before the Navy introduced thermally sprayed coatings to control corrosion on shipboard valves, joints, fittings, etc., the only means of protecting these parts was frequent repainting—often after intervals as short as six months—a labor-intensive and costly operation. This paper describes the Navy's experimental program to assess the benefits of a changeover to flame-sprayed aluminum and ceramic coatings of selected components; the reduction in man-hours achieved; the quality assurance procedure adopted; and the testing and evaluation of results.
Development of an Initial Graphics Exchange Specification Capability
Authors: Wooley D. J. , Manix M. L.
Published: January 2021

Industry has long recognized the importance of computerized data exchange. The concept of a neutral exchange format is the key to an efficient and maintainable data exchange capability due to the number of dissimilar CAD/CAM systems in use today. The capability to exchange computerized design data provides the opportunity to eliminate many redundant activities such as recreating computer data from computer-generated paper drawings. The resulting improved communication of design data between contractors, subcontractors, customers, and operation and maintenance activities can reduce costs and upgrade fleet operations. This paper focuses on the need for and the methods used to develop a, workable computerized data exchange capability. Topics of discussion include the merits of electronic data exchange, the limitations of direct translators, and the benefits of a neutral data format. A project is presented that addresses various aspects of digital data exchange within the shipbuilding industry. Emphasis is placed on two working groups that address the digital exchange of design drawings and product model data using the Initial Graphics Exchange Specification (IGES).
Engineering for Ship Production
Authors: Lamb Thomas
Published: January 2021

Engineering for Ship Production is the use of production-oriented techniques to transmit and communicate design and engineering data to various users in a shipyard. The changeover from a traditional craft-organized shipyard to one of advanced technology has obviously had a tremendous effect on all shipyard departments. It should have had its second greatest impact on the engineering department. However, many engineering departments did not rise to this challenge and, therefore, lost what might have been a lead position for directing and controlling change. Production performance depends largely on the quality, quantity, and suitability of technical information supplied by engineering. By organizing for integrated engineering and preparing design and engineering for zone construction, engineering can step forward and take its proper place and play an essential role in the renaissance of U.S. shipbuilding. Using examples, this paper describes how this can be done.
Survey-Guided Change in Ship Design and Production: Prospects and Limitations at U.S. Ship
Authors: Liker Jeffrey K.
Published: January 2021

This paper describes and analyzes an attempt to improve the ship design organization of a U.S. shipbuilder guided by data from a survey of the engineering workforce. While the survey was effective in diagnosing social and technological impediments to effectiveness and while it influenced the priorities of a task force established to improve engineering effectiveness, ultimately the task force was dissolved in response to short-term pressures to complete delivery of the first ship on a major contract on schedule. Why was this improvement effort cut short just as it was gaining momentum? The paper argues that the problems that surveys are intended to diagnose are often symptomatic of the very nature of the organization's structure and culture. Organizations are complex, dynamic systems. In the traditional, bureaucratic organizational systems that characterize U.S. shipyards, there are powerful internal dynamics that mediate against major system change. This case illustrates the paradox of using surveys to change a traditional management culture. If managers in the system had the personal flexibility or organizational autonomy to change in response to survey data, it is unlikely that their employees would have reported the problems they reported originally. Overall, this case example suggests that surveys should be viewed not as a guiding force, but rather as an input to organizational change. The survey without a well-designed and orchestrated change process will not lead to organizational improvement and may lead to a change in the wrong direction—a decline in employee morale and trust in management.
Applications of Regression Analysis in Shipbuilding Planning and Control
Authors: Hagemeister Kurt W. , Perakis A. N.
Published: January 2021

This paper offers a regression analysis framework which can be used in the day-to-day planning, control, and management of the ship construction process. The purpose of this study is to provide managers/ analysts with a statistical tool which will help predict future results and aid in better decisionmaking. The framework is presented by using a specific example--the hull block assembly process for a crude oil tanker. Four regression models are selected and analyzed for each of twelve block types. Two of the four models are found to be highly useful for the prediction of assembly man-hour costs. Of these two, the model employing weight as a predictor of man-hours is the most effective. Finally, several areas of future study are offered, based on the results of the regression analysis.
Evaluation of Commercially Available Wet Welding Electrodes for Potential Repair of U.S. Navy Ships
Authors: West Thomas C. , Mitchell Gene
Published: January 2021

As part of a program to determine the viability of underwater wet welding for repair of U.S. Navy surface ships, eight commercially available shielded metal arc wet welding electrodes were evaluated by a series of screening tests. Two E7014 "type" electrodes provided superior results and were used for welding procedure qualification testing on ASTM A-36 steel with a carbon equivalent of 0.35. Qualification testing included visual, liquid penetrant and radiographic inspection, as well as bend testing, reduced section tension testing, all-weld-metal tension testing, Charpy impact testing, macroscopic examination, hardness testing, and chemical analyses. The wet welding was performed in the vertical, overhead and horizontal positions. The welding took place at depths of 7 and 33 ft of seawater. Nondestructive and destructive test results show that both electrodes exceed the requirements of American Welding Society Specification for Underwater Welding, ANSIAWS D3.6-83, Type B. Weld quality and strength were found to be approximately on a par with welds made in an air environment. Weldment ductility and toughness were appreciably lower than would be expected of air welds.
Statement by Louis D. Chirillo to the Commission on Merchant Marine and Defense, 18 July 1988
Authors: Chirillo Louis
Published: January 2021

Mr. Chairman, Commission Members:I am pleased to submit this statement and hope that it will contribute to bettering the merchant marine and defense of our nation.
Infusing Producibility into Advanced Submarine Design
Authors: Brucker B.R.
Published: January 2021

The SEAWOLF submarine design is promoting the employment of a variety of advanced ship design and production techniques. Major goals of the design are to fully support a zone construction program, capture the database in a digital format, provide digital products for construction and logistics support and simplify, as much as possible, the construction effort. Four innovations that support these goals include: Producibility Steering Group, improved drawings, planning and sequence documents, and producibility review process. The implementation of these producibility tasks into a new submarine acquisition has required extensive development by a creative group of designers and a contingent of production planners. The SEAWOLF producibility team has undertaken the task to understand and apply the advancements in shipbuilding technology that are in place and are being implemented today. The infusion of producibility is the result of this knowledge being reflected in SEAWOLF design products.
The Construction of the T-AO 191 at Pennsylvania Shipbuilding
Authors: Lawlor John , Miller Herron
Published: January 2021

In the summer of 1985, Pennsylvania Shipbuilding Company was awarded a contract from the Navy to build two T-AO 187 class fleet oilers, T-AO 191 and T-AO 192. Subsequently, orders for two additional ships in the same series were received. The contracted delivery date is March 1989 with follow ships to be delivered at nine-month intervals. This paper describes the ships and the shipyard as well as highlights of the construction process to date with special emphasis on the use of imported technology. Particulars of the T-AO ship are provided in an Appendix.
Increased Duty Cycle for Plasma Arc Cutting Machines Through a Separated Automatic Plate Marking Station
Authors: Sizemore J. M. , Rome D. P.
Published: January 2021

Plate marking as currently practiced limits plasma arc cutting machine duty cycle. This, in turn, constrains plate fabrication process lane throughput. A separate automatic plate marking station which will significantly increase plasma arc cutting capacities is defined. A 60 to 100 percent increase in plate fabrication process lane throughput is anticipated while simultaneously reducing unit direct labor. The design is supported by technical feasibility demonstrations.