bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of the Decision-Making System for the Ship Block Logistics Based on the Simulation
Authors: Woo Jong Hun , Song Young Joo , Kang Yong Woo , Shin Jong Gye
Published: January 2021

Nowadays, the simulation technology aiming at preverifying extensively continues to develop in the manufacturing industry. Though it is possible to apply simulation methodology to various fields in various methods, in particular, the computer simulation of the production system in the manufacturing industry is applied most extensively. Lots of shipyards have made continual studies of the improvement plans on logistics operation of shipyards to cover the ship product constructed anew that consists of various ship types increasing day by day in the fixed area of the yard in recent years. The block to form a ship, a transporter to transfer the block, and the jig that is the support of the block are related physically, and the planning and scheduling and the operating scheme of the distribution are related informatively in the logistics of the shipyard. We introduce cases to build the decision-making system with which one can perform the logistics verification on the planning and scheduling and the assessment of the quantitative effect of the changes of the shipyard layout.
OPA 90: Double-Hull Tank Barges—A Small Pacific Northwest Barge Builder’s Experience
Authors: McKernan J. Cameron
Published: January 2021

This paper describes the 18 double-hull oil tank barges built by a Portland, OR, barge builder since 1993. Of the 18 barges, there are 7 completely different designs. This builder had previously built many single-hull tank barges. This paper records the experiences of this builder during development of the new designs and the constructing of the barges to conform to the new OPA 90 Regulations.
The Benefits and Cost Impact of Aluminum Naval Ship Structure
Authors: Lamb Thomas , Beavers Nathaniel , Ingram Thomas , Schmieman Anton
Published: January 2021

Due to budget pressure and a growing diversity of mission requirements, the US Navy is in need of affordable and operation-flexible ships. This paper presents an acquisition and total life cycle cost comparison of steel and aluminum equivalent naval ship designs. A common perception is that aluminum ships cost significantly more than steel ships. This paper illustrates that even though the cost of the equivalent aluminum ship structure is 40% more than the steel structure, the equivalent aluminum naval ship can be built within just 7.5% of the acquisition price of the steel ship. This is possible because of the cascading benefits of the aluminum ship's significantly lighter weight. Advances in aluminum technology and new facilities in the shipyards for aluminum production are further improving the acquisition cost of aluminum ship. From a total life cycle cost perspective, aluminum ships enjoy a clear advantage over steel ships, the details of which are provided in this paper. Based on the findings presented in the paper, it is suggested that the US Navy should consider broadening its use of aluminum ships.
Generating More Valid Designs During Design Exploration
Authors: van Bruinessen Ties , Hopman Hans , DeNucci Thomas , van Oers Bart
Published: January 2021

Concept Exploration Models (CEM) are powerful tools in the conceptual design phase, triggering naval architects towards unconventional or better solutions. However, the quality of the design-set depends on the evaluation of each concept design and its compliance to customer requirements. To improve design-set quality new evaluation-modules are developed to calculate sea-keeping, weight, and resistance and evaluate their compliance with requirements set by the U.S. Coast Guard. To make this possible the MATLAB based CEM was coupled with the sea-keeping program Shipmo2000 from the Marin Research Institute. In a final step the designs were graphically filtered and evaluated.
Study on Hull Form Optimization for Minimum Resistance Based on Niche Genetic Algorithms
Authors: Bao-ji Zhang , Kun Ma
Published: January 2021

The Niche Genetic Algorithms (NGAs) can overcome the deficiency of Genetic Algo-rithms (GAs), such as premature convergence and low ability of local search. The NGA can maintain the diversity of the individual in groups. Meanwhile, it has a high ability of globally searching and a rapid convergence rate. To get the hull form with minimum resistance, an optimization design of the hull form with NGA method, which is combined with CAD technology based on the Rankine source method, is proposed. The total resistance is taken as objective function in the optimization process, study on the optimization of the fore-body of hull is proposed, with the parameter of hull form modification function as design variables, with an appropriate displacement as the basic constraint. Initially, the Series60 hull was selected as the base for the optimized calculation. Comparison between the optimized results of the NGAs and GAs shows that the hull based on the optimized NGA are valid and effective.
Energy Finite Element Analysis for Structural-Acoustic Design of Naval Vehicles
Authors: Vlahopoulos Nickolas , Wu Kuangcheng , Medyanik Sergey
Published: January 2021

The pursuit of innovative ship designs, the use of new materials, and the increasingly demanding performance requirements dictate a broadly focused thrust for addressing noise and vibration issues during the design process. This expanded technical view also requires that the types of tools used for these assessments can provide results within a short enough time to affect the design cycle. Recently, an Energy Finite Element Analysis (EFEA) formulation has been developed for computing the vibration and the associated radiated noise of complex vehicles at frequencies where conventional finite element methods are no longer efficient. In this paper the main theoretical aspects of the EFEA are presented first. Next, a substructuring capability is described where large computational models, typical of naval applications, can be subdivided into separate domains for pursuing a compartmentalized solution and achieving further improvements in computational efficiency. Finally, validation case studies are presented with correlation between computations and scaled model testing.
A Numerical Study of a Two-Dimensional Stepped Planing Surface
Authors: Garland William R. , Maki Kevin J.
Published: January 2021

In this paper the performance of a stepped planing hull is analyzed through numerical simulation of the fully nonlinear flow under a two-dimensional body. The height and location of the step are systematically varied to investigate the resulting free-surface elevation, pressure profile on the body, and fraction of the total lift that is developed on the downstream portion of the body. The results indicate that indeed a larger step height will generate a larger lift-to-frictional-drag ratio. This suggests that the largest step possible should be chosen, with the upper bound for this dimension being the height in which the flow no longer reattaches to the after-body. The results show that the lift-to-frictional-drag ratio varies very little with respect to the step location over the range studied in this work.
Plug-In Hybrid Direct Current Distribution for Ferry Systems, Escort Tugs, and Harbor Vessels
Authors: Rozine Vassili , Ockerman John
Published: January 2021

A new conceptual approach to the design of marine electrical distribution systems is suggested as an alternative to existing methods. Ferries, escort tugs, and harbor vessels having electrical distribution systems with direct current links and battery banks have problems associated with necessity of fast battery recharging during short stops. The use of a modular approach to a battery design is a possible solution to these problems. The alternative distribution systems are examined to clarify the point.
Numerical Modeling of a Planing Hull Maneuvering in a Regular Wave, Part 1: Dynamic Instability
Authors: Lin Ray-Qing , Smith Tim
Published: January 2021

The surf rescue boat (SRB) of the U.S. Coast Guard is a class of high-speed planing boats. This 9-meter craft is capable of operating at speeds up to Froude number 1.7. However, when it begins to maneuver in incident waves near its maximum speed, dynamic instability occurs immediately. In this instance, the craft trims and rolls to a large heel angle with "plow-In," even with small-amplitude incident waves and small course changes. In this study, a fully nonlinear ship motion model named the Digital Self-consistent Ship Experimental Laboratory (DiSSEL) is used as a numerical tool to understand the physics that cause the dynamic instabilities. DiSSEL showed that when SRB reached Froude number 1.698, acceleration resulting from heading change would cause a dynamic force and moment imbalance, resulting in heel and pitch motion instabilities. DiSSEL also showed that if the heading is fixed, and other conditions remain the same, the instability did not occur. Unfortunately, there is no detailed record of the data or numerical simulation of the ship motions in the stable and unstable regions, except for the description of the ship motions by Codega and Lewis (1987). The simulations by DiSSEL agree well with this description.
Large Surface Effect Ship Size Limits
Authors: Koullias Stefanos , Robinson Santiago Balestrini , Mavris Dimitri N.
Published: January 2021

The purpose of this study is to obtain insight into surface effect ship (SES) endurance without reliance on historical data as a function of geometry, displacement, and technology level. First-principle models of the resistance, structures, and propulsion system are developed and integrated to predict large SES endurance and to suggest the directions that future large SESs will take. It is found that large SESs are dominated by structural weight, which indicates the need for advanced materials and complex structures, and that advanced propulsion cycles can increase endurance by up to 33%. SES endurance is shown to be a nonlinear discontinuous function of geometry, displacement, and technology level that cannot be predicted by simplified models or assumptions.
Development of a Large-scale Surface Effect Ship Bow Seal Testing Platform
Authors: Wiggins Andrew D. , Zalek Steven F. , Perlin Marc , Ceccio Steven L. , Doctors Lawrence J. , Etter Robert J.
Published: January 2021

A large-scale surface effect ship (SES) bow seal testing platform was constructed by the University of Michigan and is presently being commissioned at the U.S. Navy's Large Cavitation Channel (LCC) in Memphis, TN. Using a recently installed (2008) free-surface forming gate, the test platform is capable of investigating the physics of the two-dimensional planing seal and three-dimensional finger-type bow seal in calm water conditions and at scales relevant to SES designers and numerical modelers. The LCC environment permits extended run times at high Reynolds number and provides unfettered optical access to the seal geometry and flow field. This article describes the development of the testing platform and presents some preliminary results. The test platform is nominally 7.9 m long, 1.52 m wide, and 2.0 m tall and of welded and bolted steel construction. The seals are nominally sized similar to those currently used by the U.S. Navy's Landing Craft Air Cushion class. An extensive measurement suite was integrated with the test platform. The goal was to provide numerical modelers a data set with sufficient spatial and temporal resolution to validate their models of the experiment and, where appropriate, to develop new analytic models. The results of this effort demonstrate a feasible system for investigating surface effect ship seal physics within a large free surface water channel.
Comparing Trimaran Small Waterplane Area Center Hull (TriSWACH), Monohull, and Trimaran Hullforms: Some Initial Results
Authors: McDonald Tim P. , Bucknall Richard W.G. , Greig Alistair R.
Published: January 2021

Alternative hullforms such as multihulls may allow small vessels to deliver levels of performance normally associated with a far larger and more costly monohull vessel. This article describes a research program on alternative hullforms being undertaken by a consortium of six universities and academic institutions. As well as reviewing the current research program, this article discusses in detail the contribution being made by University College London (UCL): tools for undertaking the comparison and exploration of the monohull, trimaran, and Trimaran Small Waterplane Area Center Hull (TriSWACH) alternatives. These tools combine the modeling and analysis capabilities of an existing naval architecture design package with a varied range of search and optimization techniques to enable the exploration of alternative ship design solutions. This article presents the initial results obtained from tools that are currently under development at UCL. Such tools can be applied to identify and explore key topics related to the trimaran and TriSWACH hullforms when compared with a baseline mono hull configuration. The trimaran hullform has significant potential for small fast combatants as demonstrated by the U.S. Navy's LCS program. The TriSWACH hullform (with a small waterplane area center hull stabilized by two outriggers) is of interest because it offers the potential for improved seakeeping performance.
Distortion Measurement of Ship Blocks Using Photogrammetry
Authors: Mandal N. R. , Kumar Sharat , Biswas Pankaj
Published: January 2021

Welding being a transient phenomenon, explicit finite element thermomechanical analysis of large structural units is computationally extremely time-consuming and in general not feasible. Computational methods are available; however, they need to be validated with full-scale shop floor measured data. As of now, it is extremely difficult to do measurements and acquire some tangible data in actual shop floor situation. In the present work, a method was proposed to actually get the dimensions of such large structures through the use of multiple digital photographs of the structure. The photographs were then processed through a software to get to the dimensions of the threedimensional structure. For validating this method of measurement, two test cases were undertaken. First was using a flat surface plate measuring 3.3 m ×1.3 m over which black dots were pasted at predetermined positions. The distances between the dots were measured using a laser distance meter and compared with those obtained through photogrammetry. In the second case, a test sample was fabricated using a 500 m × 500 mm, 8-mm thick mild steel plate and two longitudinal and one transverse stiffener of 75 × 50 × 6 angle sections. Photographs were taken both before and after welding of the stiffeners. This set of photographs was processed to obtain the resulting deformation of the plate resulting from welding of the stiffeners. The distortion obtained through photogrammetry was compared with the distortion shape of the welded panel obtained from finite element analysis using an average plastic strain method. In both cases, the results of photogrammetry compared fairly well with those of laser distance meter measurements and finite element analysis. The proposed method shows great promise toward actual measurement of large blocks of ship structures and thereby satisfactorily validating theoretical methods of distortion prediction of such large structures.
Lean Project Planning in Shipbuilding
Authors: Emblemsvåg Jan
Published: January 2021

Lean Project Planning (LPP) is a new approach for project planning that has been developed from the Last Planner System to overcome shortcomings in the Earned Value Management approach. In this paper, we investigate how LPP has been successfully used in shipbuilding of a so called Platform Supply Vessel. Due to the highly advanced vessel, we managed to stress-test the approach and found a number of improvements to be made. However, the overall judgment is that LPP is a success. By now, these improvements are more or less implemented except those relevant for the engineering part. When it comes to the engineering processes further improvements are still needed.
The Systematic Variation of Step Configuration and Displacement for a Double-step Planing Craft
Authors: Lee Evan , Pavkov Mark , McCue-Weil Leigh
Published: January 2021

A model test was conducted to provide a systematic understanding of the effects that displacement and step location have on the performance of a stepped planing hull. Seven different step configurations were tested at three different displacements and over a range of four different speeds in calm water. Of all the configurations tested, the stepped hull configurations showed reduced resistance compared with the unstepped hull. The configuration with the smallest step height forward and the largest step height aft showed the least amount of drag over the speed range tested. The increased displacements had the same effect on craft performance for both the stepped and unstepped hulls.
Wave Wake: Focus on Vessel Operations within Sheltered Waterways
Authors: Macfarlane Gregory J. , Bose Neil , Duffy Jonathan T.
Published: January 2021

This article describes the development of an empirical tool that can rapidly and accurately predict the characteristics of the wave wake generated by vessels that typically operate within sheltered waterways, including small commercial craft and recreational vessels. A wave wake regulatory criterion is also proposed and incorporated within the prediction tool.
Institutionalizing Modular Adaptable Ship Technologies
Authors: Doerry Norbert H.
Published: January 2021

The U.S. Navy is tasked within a constrained budget with fulfilling its missions in an environment of evolving threats and a corresponding rapidly evolving mission system technology base. Modular Adaptable Ship technologies enable the affordable transformation of a ship over its service life to maintain military relevance.
Empirical Methods for Predicting Lift and Heel Moment for a Heeled Planing Hull
Authors: Judge Carolyn Q.
Published: January 2021

Even in calm water, high-speed vessels can display unstable behaviors such as chine walking, sudden large heel, and porpoising. Large heel angle can result in the loss of transverse stability at high forward speed. When a planing craft begins to plane, the hydrodynamic lift forces raise the hull out of the water, reducing the underwater geometry. An experimental program at the U.S. Naval Academy has been designed to investigate the transverse stability of planing hulls. An experimental mechanism to force a planing hull model in heave and roll motion was designed and built. The first model tested was a wooden prismatic planing hull model with a constant deadrise of 20, a beam of 1.48 ft (0.45 m), and a total length of 5 ft (1.52 m). The model was held at various heel and running draft positions while fixed in pitch, yaw, and sway. The tests were done at two model speeds, for one model displacement, five fixed heel angles, and five fixed running heave positions. The lift and sway forces, along with the heel moment, were measured and underwater photography was taken of the wetted surface. This article presents a set of equations based on empirical relationships for calculating the lift and heel moment for a prismatic planing hull at nonzero heel angles.
A Cost Forecasting Model for a Vessel Drydocking
Authors: San Cristóbal José Ramón
Published: January 2021

Approximately every 3 or 4 years, vessels have to be drydocked, either in accordance with specific rule requirements or to gain an overall view of the vessel's condition. These drydockings can incur considerable expense because they involve the inspection, overhaul, and, where necessary, the modification of existing equipment. It is imperative for ship managers and operators to monitor and control drydockings because lower drydocking costs do not just affect sound financial performance, but are also a requirement for it. This article proposes a method for forecasting the actual cost and the cost at completion of vessel drydockings based on the Gray system theory. Results show that the accuracy of the GM (1,1) forecasting model is highly efficient.
Improving the Reuse of Design Data during the Tender Phase
Authors: Stroo-Moredo Elena , Krikke Marnix
Published: January 2021

This article presents a methodology to improve the reuse of design data in the tender phase. This methodology consists of the implementation of two novel structures: a Functional Breakdown Structure and a System Breakdown Structure. The first provides a tool to capture that key data, which is currently missing, for the reuse at an early stage of design. The second structure ensures that the design data are structured, documented, and easy accessible and retrievable for new tenders. The two structures are linked to ensure the traceability and reusability of design data for new tenders.
A Method for Propeller Blade Optimization and Cavitation Inception Mitigation
Authors: Epps Brenden , Víquez Oscar , Chryssostomidis Chryssostomos
Published: January 2021

Propeller blade design for fast ships is often driven by cavitation constraints. A tradeoff exists, in which larger chord lengths and section thicknesses typically improve cavitation performance but result in lower efficiency. Typically, chord lengths are optimized for the design condition (ship endurance speed) with some specified margin to prevent cavitation off-design (at maximum ship speed). Cavitation performance at the maximum speed is considered postfacto, and blade shape often needs to be modified for cavitation considerations in high-speed operation. This article presents an improved method for blade shape optimization. The present method simultaneously considers the cavitation performance at the endurance speed design point and a maximum speed off-design point, and blade chord lengths and thicknesses are set to prevent cavitation at both operational conditions. During the present design optimization routine, the on-design load distribution is optimized, and the off design performance is determined such that the chord lengths can be set to a minimum that still prevents cavitation at both the on- and off-design conditions. A case study is presented, considering the notional design of a propeller for the U.S. Navy DDG51 destroyer-class ship. Propellers designed using standard chord/thickness optimization procedures are compared with those designed using the present procedures. Cavitation performance is compared for the two design methods.
Research on the Assembly Sequence of a Ship Block Based on the Disassembly Interference Matrix
Authors: Peiyong Li , Jin Cui , Feng Gao , Chengfang Wang , Yunsheng Mao , Guohong Liao
Published: January 2021

Reasonable optimized block assembly sequence has vital practical significance for ship construction, and the research has been done in this article at the aim of obtaining optimal assembly sequence. First, taking a double-bottom block as the object of study, by analyzing the connection relationship between each part, a disassembly network diagram and disassembly interference matrix can be generated by applying the demolition method. Based on the disassembly interference matrix, disassembly sequence can be generated according to certain rules, then the assembly sequence is the invert of disassembly sequence; next, considering comprehensively the part's physical attribute affecting the assembly sequence, the final assembly sequence can be obtained for two assembly ways using the analytic hierarchy process; lastly, DELMIA software is applied to implement the virtual simulation of the assembly process in accordance with the assembly sequence. The work of the article is of certain guidance significance to parts assembly in ship production and can lay a good foundation for realizing the ship block's digital assembly.
Block Erection in the Event of Delays in Shipbuilding: A Scenario-Based Approach
Authors: Tokola Henri Alfred , Niemi Esko , Remes Heikki
Published: January 2021

Ships are constructed from individual steel structural units called blocks, which are typically erected into the ship one by one in a sequence. This sequence, the block erection schedule, is the main schedule in shipbuilding, and it is followed in other production phases. However, the problems in the production of the blocks can delay the arrival of the blocks in comparison to what was initially scheduled. To deal with these delays, this article studies five different planning methods: erecting blocks unfinished; the use of inventories; the use of rush jobs; sequence changes; and, if the delays cannot be dealt with, delaying the completion of the ship. In order to do that, a mathematical, scenario-based mixed-integer linear programming model is formed. The model is used with numerical results to show that the block structure, delay conditions, and the tardiness costs have significant effect on the optimal use of planning methods. Results show that inventories should be used when delays are probable, whereas blocks should be erected unfinished if the delays are very uncertain and there are high tardiness penalties. The uses of rush jobs and sequence changes depend on the structure of the ship.
Understanding the Trade-offs Between Producibility and Resistance for Differing Vessels and Missions
Authors: Temple Dylan Walker , Collete Matthew
Published: January 2021

Design optimization to increase the efficiency of vessels is common place in engineering. However, most optimization focuses on a single aspect of design such as hydrodynamics, structures, or production. In reality, the lifetime cost of a ship is a combination of these different categories and, for an engineer in the design phase, it is important to understand the trade-offs between them. By understanding these trade-offs, design decisions can be made that ensure reduced costs to the shipowner. However, the development of these trade spaces is difficult and necessitates exploration over a large region of design space. As an example, this work develops these trade spaces between two major competing facets of the lifetime costs: fuel consumption and build cost. Hull forms are transformed using two independent transformation functions to rapidly alter the table of offsets defining the ship's geometry. Using this transformation method with a multiobjective genetic algorithm, Pareto fronts between a lifetime resistance metric and a producibility metric based on curvature are developed. Pareto-optimal fronts are then found for both a nominal DTMB-5145 combatant and a KCS SIMMAN container ship. With these fronts, the trade-offs in early stage hull form design is explored, and vessels that minimize these two costs are examined. The work also explores the differences between the trade spaces for the differing types of vessels and mission profiles. Using this method, these trade spaces can be used to explore the design space of vessels earlier in the design phase and gain an understanding of how decisions will affect the total lifetime costs of the ship.
Development of Risk Assessment Methodology for Occupational Safety by Work Observation Technique
Authors: Shinoda Takeshi , Tanaka Takashi
Published: January 2021

It is a challenge to prevent occupational accidents in any industrial activities. The aim of this study is to improve safety and reduce the risk of occupational accidents at shipyards by developing a risk assessment methodology using work observation technique. This article describes a concept and methodology of risk assessment for occupational safety and its application. It introduces an effective and useful assessment procedure designed from a database based on the past cases of occupational accidents at shipyards. A quantitative method is developed to understand unsafe working conditions and environment at shipyards. A mobile device is used to collect the work observation data at the shipyard, and some examples of effective hazard measures are suggested. Based on the methodology, a feasibility study was conducted to improve walking safety at a numerical control (NC) cutting process of a shipyard in Japan.
Emission and Fuel Reduction for Offshore Support Vessels through Hybrid Technology
Authors: Lindstad Haakon E. , Sandaas Inge
Published: January 2021

Traditionally, offshore support vessels have been designed to ensure that they can perform their duties at nearly any sea state. This has been achieved through multiple engines and advanced dynamic positioning systems. This in combination with high safety standards set by the oil companies has resulted in a general operational pattern with vessels running multiple engines at low-to-medium loads to be prepared for unexpected incidents to happen at any time. At medium-to-high power, the combustion engine produces each kilowatt hour with the lowest fuel consumption and the lowest emissions. When engines operate at low power, fuel consumption per kilowatt hour produced increases. For the cost of the operation, this increase in specific fuel consumption at lower loads makes a small impact compared to the total cost of the operation, while for emissions low loads implies that emissions of exhaust gases such as nitrogen oxides and aerosols such as black carbon increases rapidly due to less favorable combustion conditions. This study investigates potential emission and fuel consumption reductions, which can be achieved by introduction of hybrid technologies including their climate mitigation potential. In this context, hybrid means engines of different sizes, battery storage of energy to take peak power requirements, and power management systems with a more balanced focus on reducing emissions and energy consumption while maintaining a high safety standard. Our results indicate that hybrid technologies reduce both emissions and fuel consumption, and that the climate impact of the emission reduction is much larger than the impact due to the reduction in fuel consumption alone.
In Sight of a Fillet Joint Based on Welding Force Method
Authors: Podder Debarata , Gadagi Amith , Mandal Nisith Ranjan , Das Sreekanta
Published: January 2021

Analysis of fillet-welded T-sections was carried out using the commercial finite element software ANSYS® for SM400A shipbuilding steel. To avoid the time consuming experimental technique, this model was validated with the existing experimental and numerical results. The vertical deflection, transverse shrinkage, and longitudinal residual stress were considered to validate the present model. After validating the model, the longitudinal, transverse, and normal plastic strains were collected from flange, web, and weld bead portions throughout the thickness and were averaged. These plastic strains were converted into corresponding longitudinal, transverse, and normal welding forces and were applied in an elastic model to obtain the distortions. The average welding force method was found to be very efficient in determining the distortions of welded structures. It was found that the proper distortion pattern for single-sided fillet welding can be obtained by incorporating the additional shrinkage forces from the weld bead.
Determination of Human Error Probabilities for the Maintenance Operations of Marine Engines
Authors: Islam Rabiul , Abbassi Rouzbeh , Garaniya Vikram , Khan Faisal I.
Published: January 2021

Human error is a crucial factor in the shipping industry and not to mention numerous human errors occur during the maintenance procedures of marine engines. Determination of human error probabilities (HEPs) is important to reduce the human errors and prevent the accidents. Nevertheless, determination of HEPs in the maintenance procedures of marine engines has not been given desired attention. The aim of this study is to determine the HEPs for the maintenance procedures of the marine engines to minimize the human errors and preclude accidents from the shipping industry. The Success Likelihood Index Method is used to determine the HEPs due to the unavailability of human error data for maintenance procedures of marine engines. The results showed that among the 43 considered activities in this study, inspection and overhauls piston/piston rings have the lowest HEP meaning it has a lower consequence for accidents. On the other hand, fuel and lubricating oil filters pressure difference checking and renews filter elements activity have the highest HEP indicating it has high chances for accidents.
A Research on Simulation Framework for the Advancement of Supplying Management Competency
Authors: Woo Jong Hun , Kim Youngmin , Jeong Young-Kuk , Shin Jong-Gye
Published: January 2021

Various efforts to overcome the current crisis of shipbuilding industry have been being made in every area, including development, administration, and customer management. For overcoming the crisis, this study proposes a methodology to reconsider the supply management competency, which consists of production, procurement, and logistics, by the virtualization of Plan Do See (PDS) cycle using simulation technology and introduces a case study to verify the proposed methodology. The keys to the methodology are a comprehensive simulation framework including systematic analysis for the index investigated through simulation and a simulation platform for constructing a smooth input/output environment by avoiding dependencies on existing solutions. The systemized simulation framework is expected to maximize the speed and precision of decision-making regarding the supply management of shipyard and therefore eliminate waste elements that generate a large deficit.
Modelling of a Cruise Shipbuilding Process for Analyzing the Effect of Organization on Production Efficiency
Authors: Hellgren Sisko , Hänninen Maria , Valdez Banda Osiris A. , Kujala Pentti
Published: January 2021

This article investigates how the-organization of the shipbuilding process influences production efficiency-by creating a model of the shipbuilding process utilizing a Bayesian network. In this model, the variables are determined by factors having an impact on production efficiency. Causal dependencies between these variables create the network. Three different configurations of organization are included, namely, line organization, project organization, and a hybrid organization. All model probabilities for reaching the targeted production efficiency are elicited from experts. Based on the results, project organization has the highest probability of achieving the desired efficiency. The higher probability is mainly because, in project organization, clear responsibilities lead to target-oriented problem solving and decision making. The model demonstrates that organization has impact on production efficiency. The model can also be used for further developing the cruise shipbuilding process.
Influence of Nonsymmetric Steel Sandwich Panel Joints on Response and Fatigue Strength of Passenger Ship Deck Structures
Authors: Romanoff Jani , Ehlers Sören , Remes Heikki
Published: January 2021

Present paper investigates the factors contributing to the stress response of steel sandwich panel deck joints when applied into the hull girder of modern passenger vessel. The emphasis is put on the fatigue analysis, which is the critical design criterion in application of these structures to ships. Two types of joints are considered, i.e., a symmetrical and a nonsymmetrical prismatic joint with respect to the geometrical midplane of the sandwich panel. Stiffness properties are derived for the joints in order to enable the modeling of sandwich structures as part of the hull girder finite element model. The influence of sandwich joints to hull girder response is studied. Notch stress analysis is used for the fatigue strength estimation. The applicability of notch stress method for steel sandwich panels is validated with experiments. The investigation shows that the fatigue strength of steel sandwich panels does not depend only on local stress concentration factors at details, but also on the global stiffness of the structural hull girder system, the sandwich panels, and thus the joint response must be taken into account.
The Numerical Study of Steel Plate Forming by Moveable Induction Heating Considering the Plate Edge Shrinkage
Authors: Zhang Xuebiao , Chen Cheng , Li Jiaqin , Liu Yujun
Published: January 2021

In this article, the line heating forming technology by using the moveable induction heating is used to form a concave-type plate. In shipyard, it is necessary to get a bigger contraction deformation at the plate edge for the concave plate. However, the heat input of the metal near the plate edge is less than that of the internal metal along the heating line due to the decrease of heat power near the plate edge, thus causing smaller transverse shrinkage of the plate edge. To solve this problem, the paper investigates the suitable heating way of the inductor for the concave plate forming. An electromagnetic coupling finite element model is built to simulate the moveable induction heating process and reveal different heating and forming characteristic of different inductor heating ways. The simulation results are verified by experiments data. Research results showed that the heating way by which the inductor moves out of plate edge is an effective heating technology which meets the forming requirement of the concave plate.
Study on the Propagation of Dimensional Deviation in the Hull Block Building Process
Authors: Liu Changhui , Liu Jianfeng , Zhang Yansong , Jin Sun , Wang Can , Lai Xinmin
Published: January 2021

Dimensional accuracy of hull block plays a critical role in guaranteeing the whole ship accuracy and reducing the hull butt-joint cost. The current industry practice of dimensional control in shipbuilding mainly focuses on the prediction of cutting and welding deformation based on engineering experience. Its main limitation is that the propagation and accumulation of deviations in the whole building process are neglected. In this article, cutting errors, assembly deviations, welding shrinkages, turnover distortions, and thermal expansions generated at different stages are analyzed. The propagation and accumulation of deviations and variations in the double-bottom block building process are studied based on the measured data in the whole process. Finally, the correlations of deviations between the adjacent stage are concluded. The conclusions can be used to guide the accuracy control in the hull block building process and reduce dimension trimming.
Experimental Analysis of a Laboratory-Scale Diesel Engine Exhaust Heat-Driven Absorption Refrigeration System as a Model for Naval Surface Ship Applications
Authors: Ezgi Cüneyt , Bayrak Sinem
Published: January 2021

Decreasing industrial energy sources and major environmental problems caused by uncontrolled energy consumption have led to studies on alternative energy sources. This study presents a design and experimental analysis of an exhaust gas-driven absorption refrigeration system for the purpose of air conditioning by using the exhaust heat of a diesel engine, which is installed in the Naval Academy Mechanics Laboratory. The diesel engine is loaded with a dynamometer, and water and ammonia are used as an absorbent and refrigerant, respectively. At various diesel engine loads, cooling capacity and coefficient of performance (COP) of the absorption refrigeration system are calculated. Experimental results have indicated the cooling capacity as 1.098 kW at a maximum engine power of 4.9 HP. The highest COP value in the designed system has been calculated to be .3022 for the generator temperature of 160 C. Although the COP of refrigeration is low, the absorption refrigeration system can be provided a great cooling load from the exhaust heat of diesel engines and can be used in naval surface ships. In addition to energy efficiency of naval surface ships, infrared and acoustic signature can be minimized and a ships susceptibility can be dramatically reduced.
The Force and Moment on a Body in a Time-Varying Potential Flow
Authors: Cummins William E.
Published: January 2021

The force and moment acting on a body placed in an arbitrary, steady, potential flow were found by Lagally for the case in which the body can be represented by a system of singularities interior to the surface of the body. They were found to be simple functions of the strengths of the singularities and the character of the undisturbed stream in the neighborhood of the singularities. The present paper treats the case in which the body is subject to an arbitrary nonsteady motion (including rotation) in a stream which is changing with time. The force and moment are found to be the "Lagally force and moment" which would exist if the instantaneous flow were steady, plus additional components. For the force, these additional components are given as simple functions of the strength of the singularities used in establishing the boundary condition and of the velocity of the body. However, to obtain the moment, an integration over the surface of the body is required.
Skin Friction Resistance of Ships
Authors: Todd F. H.
Published: January 2021

The International Towing Tank Conference (ITTC) is to hold its 8th meeting in Madrid in September of this year. One of the subjects to be discussed will be the perennial one of how to estimate the resistance of a ship from that measured on a small-scale model in a towing tank. The Skin Friction Committee of the Conference was charged at the last meeting in Scandinavia in 1954, with reviewing the available data and making recommendations to the Conference in Madrid which will, it is hoped, be universally acceptable. Such a decision would remove one of the principal difficulties experienced in the use of model data in comparative studies. It is believed that a review of the present status of our knowledge in this field may be of interest to the members of the Society at this time.
Added Mass of Two-Dimensional Forms Oscillating in a Free Surface
Authors: Landweber L. , de Metcagno M. C.
Published: January 2021

The purpose of the present note is to give a unified treatment of the added mass for either horizontal or vertical oscillations at high frequency in a free surface. Although the results for the case of vertical oscillations are more or less known, some of them, such as the remarkably simple connection between the added mass and the area of section, are so obscure that they are worthy of emphasis. The review equation (1)4 of the little work that has been published for the case of horizontal vibrations indicates that the general results presented here for this case are new.
Application of Slender-Body Theory
Authors: Kaplan Paul
Published: January 2021

The vertical force and pitching moment acting on a slender submerged body and on a surface ship moving normal to the crests of regular waves are found by application of slender-body theory, which utilizes two-dimensional crossflow concepts. Application of the same techniques also results in the evaluation of the dynamic forces and moments resulting from the heaving and pitching motions of the ship, which corrected previous errors in other works, and agreed with the results of specialized calculations of Havelock and Has-kind. An outline of a rational theory, which unites slender-body theory and linearized free-surface theory, for the determination of the forces, moments and motions of surface ships, is also included.
The Motion and Internal Reactions of a Vessel in Regular Waves
Authors: Fay James A.
Published: January 2021

An analysis of the force distribution on a vessel moving into a regular wave system is presented, starting with a "cross-flow" hypothesis similar to that proposed by Munk (15) 2 for airships and applied to various aspects of vessel hydrodynamics by Weinblum and St. Denis (9), Grim (3), and Korvin-Kroukovsky (11). Expressions for the vessel motion (pitch and heave) and internal reactions (bending moment and shear) are obtained and compared with experimental measurements by Lewis (12). The agreement between theory and experiment for the motion is quite good, but for the bending moment is poor. Remarks concerning the justification of the cross-flow hypothesis are appended.
Analytical Expressions for Thrust Deduction and Wake Fraction for Potential Flows
Authors: Tsakonas Stavros
Published: January 2021

Wake fraction and thrust deduction are determined in closed-form expressions for a potential-flow case. The after body of a ship hull is represented by a sink distribution and the propeller by two superposed singularity systems. The first of these singularities simulates the uniform part (T1) of the thrust distribution and the second represents the nonuniform part (T2). A functional relationship between thrust deduction (f) and wake fraction (w) is obtained, which, when compared with the corresponding Dickmann expression, includes a correction term. The general expressions for t and w are reduced to a simpler form for the case of a body of revolution. Numerical results obtained from these reduced forms are in agreement with previous results obtained for the air-ship Akron. Additional computations are made for a hypothetical case where the body singularity distribution has a pronounced asymmetry. This computation demonstrates the important role of the nonuniform thrust distribution on the thrust-deduction fraction and confirms the belief that the nonuniform thrust could be the most decisive factor in the evaluation of the thrust deduction for the case of a very pronounced asymmetry. Since the hull is represented by discrete sources and sinks of known strength, which is a general method applicable to any form of a body, and since the thrust-loading variations, defined by T = T1 + T2 cos, represents well the important features of the propeller action, therefore, the developed analysis can be considered of general importance and applicable to most practical problems.
Wake-Adapted Screw Series Designed by Induction-Factor Method
Authors: van Manen J.D.
Published: January 2021

During the past ten years the design of wake-adapted propellers according to the circulation theory has proved its practical value. In the generally adopted method of design the Goldstein reduction factors are used [1,2]. These factors have been calculated assuming homogeneous flow and Betz' condition for minimum loss of energy [3, 4]. Therefore, the application of these factors for wake-adapted screws results in approximations.
Thermal Stresses in the SS Boulder Victory
Authors: Meriam J. L. , Lyman P. T. , Steidel R. F. , Brown G. W.
Published: January 2021

The lack of comprehensive experimental measurements of thermal stresses induced in a ship's hull structure by diurnal temperature changes prompted the present study. Its essential purpose is to provide reliable prototype measurements of thermal stress patterns around a complete transverse section. These results are compared with stresses computed by the theory of simple beams under arbitrary temperature distributions across their section. The research was conducted under direct sponsorship of The Society of Naval Architects and Marine Engineers at the Maritime Reserve Shipyard in Richmond, Cal. The SSBoulder Victory was supplied as the test vessel by the Maritime Administration. The ship was instrumented during June and July, 1957, and tests run during August. Various temperature conditions were observed and corresponding strain measurements taken. The results are consistent and give a reliable picture of thermal-stress conditions in the ship. They also verify the prediction of thermal stresses afforded by the simple beam theory.
The Moment Acting on a Rankine Ovoid Moving Under a Free Surface
Authors: Pond H. L.
Published: January 2021

The moment acting on a Rankine ovoid moving under the free surface of a fluid of infinite depth is calculated. The solution is carried through two approximations. The results of the second approximation are shown to be in excellent agreement with available experimental data.