bluuebunny/crossref_metadata_2025 huggingface dataset:
Michell Investigation of the Significant Influence on the Hydrodynamic of a Warp-Chine Pentamaran
Authors: Sulistyawati W. , Yanuar _ , Pamitran A. S.
Published: January 2021

This study attempted to investigate the hydrodynamic performance of various pentamaran configurations with a focus on the interference flow around the component hulls. A computer simulation was conducted based on Michell’s thin ship theory alongside a commercial CFD computation as a comparison. Experiments in the towing tank were performed to validate the numerical calculations, resulting in some hydrodynamic characteristics on the far-field wave pattern, wave interference, wave resistance, and total resistance. Analyses on both transversal and divergent waves were performed to assess the magnitude of wave resistance occurring due to the placement of the side hull to the main hull. Analyses on both waves were also conducted to assess the magnitude of wave resistance due to the placement of outriggers. Looking at the results, numerical calculations based on Michell’s theory were in parallel with experimental data, particularly at Fn greater than .4. Michell’s theory was observed as doing a little preferable agreement with the results of experiments than CFD. Besides, flow patterns obtained numerically from Michell’s and CFD analyses appeared as identical to photographs observed in a towing tank. This investigation identified that a configuration with aligning placement of the main to side hull on the formation of arrow tri-hull, near the Kelvin angle, would cancel the wave formed by the leading hull and can be used as a practical setting to reduce the total wave resistance.
Ship Robust Design Optimization Based on Polynomial Chaos Expansions
Authors: Wei Xiao , Chang Haichao , Feng Baiwei , Liu Zuyuan
Published: January 2021

Considerable parameter perturbations occur owing to the influence of uncertain factors in actual ship transportation, resulting in a substantial decline in ship performance. These parameters should not be regarded as certain values but uncertain variables. Ship robust design optimization (RDO) is a method in which various uncertainties are fully considered in the early stages of ship design to ensure that the optimal case adapts to the perturbation of the uncertain parameters. In this study, instead of the commonly used Monte Carlo method, polynomial chaos expansions (PCEs) are adopted to quantify the uncertainty, and an improved probabilistic collocation method (PCM) based on the linear independence principle is proposed to select sample points for calculating polynomial coefficients of PCE, which not only reduces the number of collocation points compared with the traditional statistical sampling method but also avoids the problem that arises with the traditional PCM, which cannot maintain high calculation accuracy even with considerable collocation points. Finally, to ensure ship robustness, in comparison with deterministic optimization design, the proposed RDO framework is applied to minimum Energy Efficiency Design Index (EEDI) KRISO Container Ship hull form design.
A Scenario Simulation - Evaluating Evacuation Analysis for ro-ro Passenger Ship in MV Tai Hwa
Authors: Wang Hui-Chiao , Wu Chien-Hsing
Published: January 2021

The ro-ro passenger ship is a type of passenger ship which is commonly seen in Europe. After the tragedy of MV Estonia, an effective evaluation of escape routes in passenger ship in the initial stage of ship design has been required by International Convention for the Safety of Life at Sea (SOLAS) Convention. To reduce the loss of life in passenger ships at sea, the International Maritime Organization (IMO) has created the revised guidelines on evacuation analyses for new and existing passenger ships. This article followed IMO's mandatory guidelines via using the hydraulic model of emergency egress to scrutinize the evacuation routes, congestion points, and the total evacuation duration of MV Tai Hwa.
Analysis and Modeling the Energy System of a Chemical Tanker by LEAP
Authors: Sari Alperen , Sulukan Egemen , Özkan Dogus
Published: January 2021

Maritime transportation has been a cost-effective option among other transport modes. Meanwhile, this demand has been increasing day by day because of the expanding global economy. The ships are one of the most important transport and trade vehicles in the world; 90% of the world trade is carried out by maritime transport, and this sector plays a crucial role in climate change and global warming because it is one of the key sectors leading to emissions of carbon dioxide, the main greenhouse gas (GHG). In other sectors that lead to CO2 emissions, i.e., energy production, manufacturing industry, and heating in residences, energy efficiency has been improved and emissions have been reduced significantly. However, there has been no net reduction in the transport sector; total CO2 emissions have also increased because of the continuous increase in freight and passenger traffic, although efficiency has increased. Increasing the energy efficiency of a ship allows for fuel consumption reduction and GHG emissions. In this study, the energy system of a chemical tanker ship was analyzed and then modeled by using the long-range energy alternatives planning system, a widely used platform for energy policy analysis and climate change mitigation assessment, including a comprehensive energy flow diagram, namely, reference energy system. A base scenario was developed, and the ship’s energy system was convenient to be analyzed and evaluated in terms of technical, economic, and environmental aspects, including low-emission development strategies, to comply with marine engine regulations of the International Maritime Organization.
Elastic-Plastic Analytical Solution for SEMI’s Horizontal Brace with a Circumferential Through Crack under Tension and Bending
Authors: Wang Fei
Published: January 2021

The elastic-plastic behavior of semi-submersible’s horizontal brace with a circumferential through crack which lies at its boundary was studied. Both tension and bending were considered to investigate the closed-form analytical solution. The results indicate that the tensile plastic zone and crack tip opening displacement (CTOD) on the cracked section increase sharply after a smoothly increment when loads became larger. The cracked horizontal brace with a greater initial circumferential through crack has a larger tensile plastic zone and earlier compressive plastic zone appearance on the cracked section. Compared with the load of tension, the bending load has larger effect on the plastic zones of the cracked section and CTOD of the crack.

Introduction

Since the first semi-submersible platform (SEMI) named as “Ocean Driller” which was designed for drilling wells in the ocean, the SEMIs have gained popularity in the recent decades with ongoing development in oil and natural gas exploration in deepwater. Because of the high risk of environment pollution and casualties of operators which a destruction accident of SEMI might bring, making sure the structure is safe during its service life has become the most important task of SEMI designers and operators. Although the safety design standards for SEMI structures are quite strict, cracks inescapably are initiated during their service life. According to the destruction accidents happened before, Moan (2009) and Zaron et al. (2015) found that the cracks often occur at the horizontal braces which function as the supporting structures in SEMIs and bear complex loads. The presence of such cracks at critical locations can compromise the safety of the braces and then can cause serious disaster eventually. Because of the initial fracture of a horizontal brace, e.g., the accident of Alexander Kielland platform, the loads were transferred to the other braces and led them break because of the overload (see Colin et al. [2014]).
Application of Michell’s Integral to High-Speed Round-Bilge Hull Forms
Authors: Lin Du , Prasanta Sahoo K. , Hamid Hefazi
Published: January 2021

Computational fluid dynamics (CFD) techniques are becoming increasingly popular in analyzing fluid flow problems in almost all branches of engineering, especially in resistance prediction of ships where complex fluid flow exists, although absolute accuracy is still limited. Application of CFD techniques in resistance prediction of ships is no longer new and is being enthusiastically embraced by researchers as can be seen from articles in journals and conference proceedings. Although the towing tank tests provide better absolute accuracy, modification to hull forms is limited, resulting from both practical and financial constraints. In this respect, CFD techniques and theoretical formulations have an added advantage in the sense that rapid modifications to hull forms can be carried out and results can be obtained, so that a comparative study could be made within a few hours. In this way, a naval architect is in a better position to select a hydrodynamically efficient design. Furthermore, robust and fast hydrodynamic computational methods are essential elements of advanced numerical optimization techniques. A good high-speed design should have favorable resistance qualities, so that operational capabilities are not degraded. Innumerable investigations available in the literature enumerate resistance prediction of systematic series of high-speed hull forms. In this article, the results of a comparative study on resistance of high-speed round-bilge hull forms using CFD techniques, theoretical analysis, and experimental results have been presented. The need for better hull forms and the increased interest in resistance performance call for better data and efficient algorithms to be available at the design and optimization stage to obtain the right balance between resistance and other conflicting requirements. This article provides a study of the following. The result of modeling in SHIPFLOW, which uses a combined potential-flow boundary-layer viscous-flow zonal approach. Application of a fast resistance estimation method with the wave-making resistance by Michell’s integral, the friction resistance by International Towing Tank Conference 1957. Application of Michell’s integral to determine the wave resistance of the systematic series models. Comparison between the total resistance coefficients obtained from experimental work, SHPFLOW, and the fast resistance estimation method.
Empirical Assessment Method of Ultimate Capability of Steel Stiffened Panel under Longitudinal Compressive Load
Authors: Pan Jin , Wang Tao , Xu Ming Cai , Gao Gui
Published: January 2021

The hull block erection network process, which is performed during the master production planning stage of the shipyard, is frequently delayed because of limited resources, workspace, and block preparation ratio. In this study, a study to predict the delay with respect to the block erection schedule is conducted by considering the variability of the block preparation ratio based on the discrete event simulation algorithm. It is confirmed that the variation of the key event observance ratio is confirmed according to the variability caused by the block erection process, which has the minimum lead time in a limited resource environment, and the block preparation ratio. Furthermore, the optimal pitch value for the key event concordance is calculated based on simulation results.
Early-Stage Naval Ship Distributed System Design Using Architecture Flow Optimization
Authors: Parsons Mark A. , Kara Mustafa Y. , Robinson Kevin M. , Stinson Nicholas T. , Brown Alan J.
Published: January 2021

This article describes an architecture flow optimization (AFO) method for naval ship system design. AFO is a network-based method. It is used to design and analyze naval ship Mission, Power, and Energy Systems (MPES) in a naval ship Concept and Requirements Exploration (C&RE) process at a sufficient level of detail to better understand system energy flow, define MPES architecture and sizing, reduce system vulnerability, and improve system reliability. This method decomposes MPES into three architectures: logical, physical, and operational which describe the system’s spatial, functional, and temporal characteristics, respectively. Using this framework, the AFO incorporates system topologies, input/output energy coefficient component models, preliminary arrangements, and (nominal and damaged) steady-state operational scenarios into a linear optimization method to minimize the energy flow cost required to satisfy all operational scenario demands and constraints. AFO results are used to inform system topology design and assess the feasibly and survivability of representative designs in the C&RE process. AFO results may also be used in physics-based vital component sizing, calculation of vulnerability/effectiveness metrics in the C&RE process, and subsequent linear optimization formulations to assess recoverability and operational effectiveness in the time domain.
MarineTech Project—Attracting Students towards Math and Science Careers in Shipbuilding and Repair Industry
Authors: Verma Alok K. , Ferrari Ray , Talaiver Manorama , McKinney Sueanne E. , Dickerson Daniel , Chen Deborah
Published: January 2021

Low enrollment and high attrition rates in science, technology, engineering, and math (STEM) based degree programs have created a shortage of workforce in industries such as shipbuilding and repair that are important for national security. Part of this problem can be attributed to pedagogical issues such as lack of engaging hands-on activities used for math and science instruction in middle and high schools. Another reason for this is that the teachers are not trained in taking an integrated approach to teaching math and science. This has led to large-scale flight and attrition from STEM-based career tracks. Consequently, engineering and engineering technology programs throughout the nation have observed declining graduation rates and quality of incoming students. To engage students' interest in STEM-based careers, it is important that students establish a link between the math and science instruction and its application to solve real-life problems early in their learning experience. Project-based activities have a proven record as a pedagogical method. Effectiveness of this pedagogy has been supported by research in the acquisition and retention of knowledge. The MarineTech Project funded by the State Council of Higher Education of Virginia and supported by the shipbuilding and repair industry has attempted to address the quality of STEM education in Virginia by developing project-based learning kits and providing professional development training in the use of these kits. The project also provided teacher training in 21st century skills and integrated math and science education while increasing awareness of teachers about the shipbuilding and repair industry. The paper presents the motivation behind developing these project-based learning (PBL) modules, issues related to implementation, and results from student and teacher workshops.
Thermal Comfort Conditions in Ships
Authors: Orosa José A. , Iradi Guadalupe , Oliveira Armando C.
Published: January 2021

Ship indoor environments are related with comfort conditions and health risk problems. As a consequence, to obtain an adequate heating, ventilation, and air conditioning (HVAC) system, a redesign of the engine control room must be made. To answer this problem, an analysis of real thermal comfort conditions was carried out and a new air conditioning procedure is proposed. From the obtained results it can be concluded that comfort conditions in the bridge and dining room are close to neutral, while the most extreme conditions have been found in the engine room.
Testing of Acoustic Emission Technology to Detect Cracks and Corrosion in the Marine Environment
Authors: Wang Ge , Lee Michael , Serratella Chris , Botten Stanley , Ternowchek Sam , Ozevin Didem , Thibault Jack , Scott Rex
Published: January 2021

Real-time monitoring and detection of structural degradation helps in capturing the structural conditions of ships. The latest nondestructive testing (NDT) and sensor technologies will potentially be integrated into future generations of the structural integrity management program. This paper reports on a joint development project between Alaska Tanker Company, American Bureau of Shipping (ABS), and MISTRAS. The pilot project examined the viability of acoustic emission technology as a screening tool for surveys and inspection planning. Specifically, testing took place on a 32-year-old double-hull Trans Alaska Pipeline System (TAPS) trade tanker. The test demonstrated the possibility of adapting this technology in the identification of critical spots on a tanker in order to target inspections. This targeting will focus surveys and inspections on suspected areas, thus increasing efficiency of detecting structural degradation. The test has the potential to introduce new inspection procedures as the project undertakes the first commercial testing of the latest acoustic emission technology during a tanker's voyage.
Impact of Pontoon Vessel Geometry on Allowable Passenger Weight Using USCG Pontoon Simplified Stability Test
Authors: Myatt Lisa L. , Thomas Brian , Taylor Todd
Published: January 2021

A parametric analysis of stability was performed for more than 30,000 geometric variants of cylindrical-hulled pontoon vessels to quantify the impacts of vessel geometry and prepassenger displacement on the maximum passenger weight allowed by the US Coast Guard (USCG) Pontoon Simplified Stability Test (PSST). Variables examined included pontoon diameter, pontoon length, pontoon separation, deck height, passenger deck width, location of forward and aft edges of the passenger deck, prepassenger displacement prior to loading, and trim. Each pontoon vessel variant was evaluated using General Hydrostatics Software to apply the PSST to determine the maximum passenger weight allowed for that vessel. Graphical analysis of the data demonstrated that a vessel's allowable passenger weight increases with: an increased pontoon diameter or length of pontoon, a decreased deck height, a limited increase in pontoon separation or beam ratio, and a symmetrically decreased passenger deck width or length. Additionally, it was found that each specific vessel has an optimum prepassenger displacement, unique to its pontoon diameter and length of pontoons, which maximizes the allowable passenger weight. Finally, a method is provided to correlate the present results with prior related work by other authors that characterized pontoon vessel stability in the context of pontoon percent submergence.
The Decay of the Andrea Doria
Authors: Sims Philip , Moyer John , Gatto Steven
Published: January 2021

The decay of sunken ships is slow and most often unobserved, so it has never been accurately described. The sinking of the liner Andrea Doria in 1956 produced a wreck of unusual characteristics. Because of the newsreel camera planes circling overhead, the sinking is world famous. It is in water marginally accessible by normal air divers. It is near a large city so there is a population base that has people interested in ships with access to boats, and, in summer, the weather is calm (sometimes). The result of these circumstances is that the ship has been continually visited by amateur and commercial divers ever since her sinking more than 50 years ago. These divers have created a database of how a modern metal ship decays through their pictures and written records. Some of the damage to the ship has been done by the divers themselves, such as cutting a side access hole in order to remove a safe for a TV show. Snagged fishing trawler nets have ripped off exposed items as well. However, the majority of the damage is being done by the ocean itself as it oxidizes the metal hull of the ship, which is gradually collapsing on itself (and crushing any interesting artifacts left inside), plus the damage of storm swell pounding and tidal flow. This paper compiles observations of the Andrea Doria through the years into a portrait of the natural decay of a major ship in the depths.
Development of a Logic-Based Product Life-Cycle Management (LBPLM) System for Shipbuilding Industry—Conceptual Development
Authors: Sharma R. , Tae-wan Kim
Published: January 2021

Product life-cycle management (PLM) has become something like "a magic wand" for various industries because of its capability to integrate different product modules via online network through the product's complete life cycle and hence to provide one-window access, thereby making the whole processes of product conception, design, manufacturing, delivery, maintenance, and disposal integrated with a reduction in product development time and cost. However, heavy industries (i.e., shipbuilding and shipbreaking) are different from consumer product industries because of high customization in design process and engineering software, widely varying scales of operations, and less compatibility between different design and production processes, for example, ship production is planned in activity-driven network scheduling system, in general, and is assumed to be more of a construction process or assembly process rather than a production process. In this paper, we present the conceptual development and the basic building concepts for a logic-based PLM system for the shipbuilding industry. Our logic bases consist of modularization, standardization, geographical zoning, and functional zoning. The logic bases of modularization and standardization are used in the ship design and production processes, and the logic bases of geographical zoning and functional zoning are used in "logically grouping" the on-board activities in the ship production process. Overall, this paper introduces a logic-driven methodology for PLM: planning and integration of ship design and production processes. Finally, in our implementation we show that by developing a logic-based PLM system the ship design and production processes become more streamlined and better planned and executed.
A Multidisciplinary Design Optimization Approach to Relating Affordability and Performance in a Conceptual Submarine Design
Authors: Vlahopoulos N. , Hart C. G.
Published: January 2021

A multidisciplinary design optimization (MDO) framework is used for a conceptual submarine design study. Four discipline-level performances—internal deck area, powering, maneuvering, and structural analysis—are optimized simultaneously. The four discipline-level optimizations are driven by a system level optimization that minimizes the manufacturing cost while at the same time coordinates the exchange of information and the interaction among the discipline-level optimizations. Thus, the interaction among individual optimizations is captured along with the impact of the physical characteristics of the design on the manufacturing cost. A geometric model for the internal deck area of a submarine is created, and resistance, structural design, and maneuvering models are adapted from theoretical information available in the literature. These models are employed as simulation drivers in the discipline-level optimizations. Commercial cost-estimating software is leveraged to create a sophisticated, automated affordability model for the fabrication of a submarine pressure hull at the system level. First, each one of the four discipline optimizations and also the cost-related top level optimization are performed independently. As expected, five different design configurations result, one from each analysis. These results represent the "best" solution from each individual discipline optimization, and they are used as reference for comparison with the MDO solution. The deck area, resistance, structural, maneuvering, and affordability models are then synthesized into a multidisciplinary optimization statement reflecting a conceptual submarine design problem. The results from this coordinated MDO capture the interaction among disciplines and demonstrate the value that the MDO system offers in consolidating the results to a single design that improves the discipline-level objective functions while at the same time produces the highest possible improvement at the system level.
Hydrodynamics of the Ballast-Free Ship Revisited
Authors: Kotinis Miltiadis , Parsons Michael G.
Published: January 2021

In order to clarify the existence and amount of a required propulsion power reduction possible with the efficient use of the Ballast-Free Ship concept on a Seaway-size bulk carrier, additional experimental and computational hydrodynamics studies were undertaken during the past year. Experimental studies performed in the University of Michigan Marine Hydrodynamics Laboratory (MHL) are described. Computational fluid dynamics (CFD) investigations performed using Star-CCMþ at both model and full scale are also presented.
Origin and Characteristics of the Spray Patterns Generated by Planing Hulls
Authors: Savitsky Daniel , Morabito† Michael
Published: January 2021

Analytical and experimental studies were made of the origin and characteristics of the two distinctly different appearing spray patterns associated with prismatic planing hulls. It was found that these two spray patterns, identified as "whisker spray" and "main spray," are a consequence of the same basic hydrodynamic flow phenomenon and transform seamlessly from one into the other. Similar to the analytical treatment developed for swept-wing aircraft, where the oncoming free stream velocity is divided into components normal to and along the leading edge of the swept wing, the free stream velocity for the planing surface is divided into components normal to and along the stagnation line. Combining this orientation of velocity components with the results of analytical studies of Wagner (Uber stoss-und gleitoorgauge an der oberflache von flussiglaseiten. Z.f.a.M.M., 2, 4, 1932) for two-dimensional planing of infinitely long flat planing surfaces with those of Green (The gliding of a flat plate on a stream of finite depth, Proceedings of the Cambridge Philosophical Society, 31, 1935) for planing of a two-dimensional, finite length surface, explains the origin and characteristics of both the whisker and main spray patterns. It is shown that the main spray originates in a small local area at the intersection of the stagnation line with the chine. Relatively simplistic equations that define the three-dimensional location of the spray apex are developed, and the results presented in three graphs. An illustrative example is presented that demonstrates the ease of application of the method to define the main spray geometry of a typical planing craft. Model tests were conducted to define the maximum height of the main spray and its lateral and longitudinal positions relative to the hull as a function of deadrise angle, trim angle, and speed coefficient. These data substantiate the analytical results.
Alternatives for Joining Stainless Steel to Reduce Cr(VI) Emissions and Occupational Exposures
Authors: Paulson K. M. , Wang J. , Topham N. , Wu C. Y. , Alexandrov B. T. , Lippold John C. , Es-Said O. S.
Published: January 2021

Welding stainless steel generates hazardous air pollutants (HAPs). Two technologies were developed to reduce these HAPs. The first, tetramethylsilane is added to the welding shielding gas, and welding proceeds as normal. Reactive oxygen species are consumed, and the resulting metal fume particles are encapsulated. In the second technique, new chromium-free welding consumables are introduced nearly eliminating Cr(VI) in the welding fume.
A Novel Ship Subdivision Method and its Application in Constraint Management of Ship Layout Design
Authors: de Koningh Deniz , Koelman Herbert , Hopman Hans
Published: January 2021

Conventionally, the rooms and spaces of a ship are either modeled as volumetric entities, or with the aid of bulkheads and decks. According to our knowledge, no simple representation exists where both entities can be modeled independently, and where automated conversion from one view (volumetric) to the other (planes) is possible. This paper introduces a simple yet effective approach, where a ship designer can mix the use of volumes and planes in any fashion. Furthermore, this modeling method is applied in a novel tool to manage ship subdivision constraints. As quite a few numerical constraints are known a priori, they can be defined in a list and assigned to specific subdivision elements. Examples are bulkhead locations or required tank volumes or deck areas. A constraint management tool is developed that evaluates the ship layout design during the design process. The designer will be able to modify or add constraints, and the tool will support the designer by managing these constraints during the design process. If the hull form changes, all submitted rules will be updated according to the new main particulars. If one of the constraints does not comply, an adjustment or alternative can be chosen at that moment and the impact of this change is directly visible. The designer can also ask the tool to provide a ship layout design that complies best with the constraints entered. When the Constraint Management program is used, a feasible ship compartment design can be made in a quick manner and the designer is kept from making errors. This means that a correct ship layout model is available on which probabilistic damage stability calculations and weight estimations can be performed in an early stage. This method has been implemented in a computer program, so actual design examples are discussed.
Technical Parameter Analysis of High-Frequency Induction Heating Applied to Steel Plate Bending
Authors: Zhang Xue-biao , Liu Yu-jun , Yang Yu-long , Ji Zhuo-shang , Deng Yan-ping
Published: January 2021

This paper describes the study of hull plate forming by high-frequency induction heating. A finite element model of static large-scale heating is performed and verified by experiments. It can be proposed to be a powerful alternative tool to the actual induction heating process. Parameters influencing the temperature and deformation are deduced.
Integrated Electric Plants in Future Great Lakes Self-Unloaders
Authors: Parsons Michael G. , Singer David J , Denomy Samuel J.
Published: January 2021

The feasibility and potential benefits of using Integrated Electric Plants in future Great Lakes self-unloaders are evaluated. Integrated Electric Plants, the all-electric ships, utilize electrical propulsion motors and central station power generation that powers all propulsion, thruster, self-unloading equipment, and other ship service needs. Integrated Electric Plants have become the plant of choice in many recent naval vessels, cruise ships, high technology cargo vessels, and special purpose vessels, such as offshore supply and service vessels and icebreakers. This study considers arrangements, effects on cargo capacity, fuel usage, and environmental emissions in all operating modes, maintenance requirements, and manning. The comparison is made for two notional self-unloading bulk carriers: a 1000 ft Poe Lock maximum self-unloader and a 730 ft MacArthur Lock, Welland Canal, St. Lawrence Seaway maxi-mum self-unloader.
Impact of Customization on Delivery Schedules
Authors: Storch Richard Lee , Lim Sanggyu , Kwon Chi-Myung
Published: January 2021

Effective commercial shipbuilders utilize the principles of mass customization to achieve production efficiencies. This approach can allow new ship designs to satisfy specific customer requirements without substantially impacting the cost or delivery schedule. In part, this is achieved by maintaining learning curve benefits at individual workstations, where similar but nonidentical interim products are produced. The changes to an existing design when employing mass customization can be estimated in design and production effort required to implement the changes. Using a notional ship design and a notional shipyard production process, this study uses Monte Carlo simulation to evaluate the impacts of various levels of change on delivery performance.
A Comparison of Several Strategies to Optimize a Ship’s Aft Body
Authors: van der Ploeg Auke
Published: January 2021

This paper describes a procedure to optimize ship hull forms, based on double body viscous flow computations with PARNASSOS. A flexible and effective definition of parametric hull form variations is used, based on interpolation between basis hull forms. One of the object functions is an estimate of the required power. In this paper we will focus on how to improve this estimate, by using the B-series of propellers. Results of systematic variations applied to the VIRTUE tanker together with scale effects in the computed trends will be discussed. In addition, we will demonstrate how the techniques discussed in this paper can be used to design a model that has a wake field that strongly resembles the wake of a given containership ship at full scale.
A Particle Swarm Algorithm-Based Optimization for High-Strength Steel Structures
Authors: Ehlers Soren
Published: January 2021

Crash resistant ship structures with high post accidental residual strength are more and more important as a requirement of Goal Based Standards. A first step in the development of structures, which fulfill these requirements, is the rational identification of crashworthy structural concepts. Therefore, efficient optimization algorithms are needed, besides reliable numerical collision simulations. Particle swarm optimization (PSO) algorithms tend to improve the objective fast, which makes them a good choice for lengthy nonlinear finite element-based collision simulations. As an application of PSO and numerical collision simulations a liquefied natural gas tanker is optimized for crashworthiness. Furthermore, one concept using normal shipbuilding steel only and one concept using a combination of normal and high strength steel is investigated. Hence, it will be shown if the benefits from high strength steel outweigh the increase in cost. Therefore, it will be shown if the combination of normal and higher strength steel can result in increased crashworthiness, even though the high strength steel has a lower failure strain when compared with the normal steel.
Effect of Container Stack Arrangements on the Power Optimization of a Container Ship
Authors: Hassan Khairul , White Maurice F. , Ciorta Cosmin
Published: January 2021

When considering the design of a ship, an important objective is to always try and develop one that allows for maximum cargo capacity with the lowest propulsion power requirement while providing a sufficient amount of strength and stability for its safe operation. The ship with the lowest propulsion power consumes the least amount of fuel and produces the lowest amount of exhaust gas that may be harmful to the environment. In some cases, the aerodynamic resistance can be neglected, but for a high speed vessel such as a modern containership, the air resistance can be in the range of 2% to 10% of the total resistance. Aerodynamic resistance can therefore have a significant effect on power requirements and is strongly influenced by the height, breadth, and the number of container stacks on the deck. The freeboard, beam of the ship, deck house design, ship speed, wind speed, and water flow direction will also contribute significantly to a ship's resistance and required propulsive power. This paper outlines the application of computational fluid dynamic simulation as a design tool to find a strategy for the optimal arrangement of the container stacks on deck so that the vessel uses the lowest effective propulsion power to achieve a fuel efficient ship. It is deduced that an optimal stack arrangement can reduce air resistance by about 30%.
The Numerical Analysis of Temperature Field During Moveable Induction Heating of Steel Plate
Authors: Zhang Xue-biao , Yang Yu-long , Liu Yu-jun
Published: January 2021

In shipyards, hull curved plate formation is an important stage with respect to productivity and accuracy control of curved plates. Because the power and its distribution of induction heat source are easier to control and reproduce, induction heating is expected to be applied in the line heating process. This paper studies the moveable induction heating process of steel plate and develops a numerical model of electromagneticthermal coupling analysis and the numerical results consistent with the experimental results. The numerical model is used to analyze the temperature changing rules and the influences on plate temperature field of heating speed of moveable induction heating of steel plate, and the following conclusions are drawn. First, the process of moveable induction heating of steel plate can be divided into three phases of initial state, quasi-steady state, and end state. The temperature difference between the top and bottom surfaces of the steel plate at the initial state is the biggest; it remains unchanged at the quasi-steady state and it is the smallest at the end state. Second, obvious end effect occurs when the edges of the steel plate are heated by the inductor, which causes a decrease in temperature difference between the top and bottom surfaces of the steel plate that is unfavorable for formation of pillow shape plates. Third, with the increase of heating speed, the temperature difference between the top and bottom surfaces of the steel plate increases gradually.
Statistics and Design Implications of Extreme Peak Vertical Accelerations from Slamming of Small Craft
Authors: McCue Leigh
Published: January 2021

Inspired by Grimsley et al. (2010) this work began with an examination of the nature of slam data statistical fitting. Specifically, the author wished to extend Grimsley's work with an eye toward appropriate statistical distribution identification for slam responses characterized as an >, A, or C event per Riley et al. (2010). With this information in hand, the author then returns to a discussion of the fundamental work by Fridsma (1969, 1971), Allen and Jones (1978), Jones and Allen (1972), and others to discuss the implications of nonexponentially distributed slam data on small craft design.
Stern End Bulb for Energy Enhancement and Speed Improvement
Authors: Karafiath Gabor
Published: January 2021

Unlike the bow bulb, the stern end bulb (SEB) has been used on just a few ships to improve performance. In one of these rare, full-scale applications, a maximum resistance reduction in the 5% to 7% range is claimed. A few applications of SEBs are shown along with some model test data for a Naval Auxiliary ship. The rationale for SEB is discussed along with the hydrodynamic mechanism associated with a SEB. In addition to wave-making reduction, the SEB can reduce eddy-making and possibly improve course-keeping. The results of several fluid flow computations with initial SEB designs are shown for two ship classes: the T-AKE LEWIS and CLARK dry cargo ship and the DDG 51 ARLEIGH BURKE destroyer. The calculations use the Ship Wave Inviscid Flow Theory potential flow computer code and the FreeRans viscous flow free surface computer code. Several SEBs were designed and investigated analytically for the T-AKE class ships, and the best of these is predicted to reduce resistance by 4.5% at 20 knots. In addition, several initial SEB/Stern Flap configurations were designed for the DDG 51 Class Flight IIa destroyers and five configurations, some with just an SEB added to the hull and others with a combined SEB-Stern Flap configuration were model-tested. The examination of these initial efforts led to the design of several new-style combined SEB-Stern flap configurations, the best of which is predicted to save at least 745 Bbls of fuel per ship per year.
Hydrodynamic and Supportive Structure for Gated Ship Sterns: Amphibious Ship Stern Flap
Authors: Cusanelli Dominic S.
Published: January 2021

Stern flaps have now been at sea for more than two decades on a variety of U.S. Navy (USN) and U.S. Coast Guard classes, including destroyers, cruisers, frigates, cutters, and patrol craft. Application of flaps to large-deck amphibious-type ships is a fairly recent extension of the technology. Ship performance improvements such as delivered power reduction and fuel savings, and maximum speed increases, have been proven during at-sea trials and are well documented (Cusanelli 2002). USN amphibious ships contain well decks, which are accessed through large folding stern gates. When open, the gates are supported by sizable structures, which are partially submerged and affixed to the transom. A new concept, the hydrodynamic and supportive structure for gated ship sterns, i.e., the amphibious stern flap, was developed and patented by the author (Cusanelli 2004a). This design combines a stern flap's hydrodynamic performance surface with the stern gate support structure. The Naval Surface Warfare Center, Carderock Division, has now designed and implemented this new type of integrated stern flap and gate support structure on several USN amphibious ship classes. USN ship design and research and development (R&D) programs have resulted in amphibious stern flaps being implemented as new construction items on two new Navy amphibious ship classes and one new subclass. The Fleet Readiness R&D Program has funded amphibious stern flap design, retrofit installations, and evaluation trials on two existing amphibious ships. Each amphibious stern flap design spiral, model-test series, optimization, full-scale implementation as well as performance benefits and fuel savings are discussed.
Dynamics and Stability of Boats With Aerodynamic Support
Authors: Matveev Konstantin I. , Kornev Nikolai
Published: January 2021

Aerodynamic support is beneficial for achieving very high speeds of marine transportation. Wing-in-ground vehicles, power-augmented ram platforms, and ultrafast planing multihulls are examples of marine craft with air assistance. The main technical problems in the development and application of these concepts for marine transportation are to ensure motion stability and to provide adequate seaworthiness. In this article, we illustrate applications of several mathematical models for various air supported marine vehicle concepts and discuss their specific stability issues. The aerodynamic submodels are based on nonlinear vortex-lattice methods and on the extreme ground effect theory, whereas unsteady hydrodynamics of planing surfaces are treated with added-mass strip theories. The static and dynamic stability in the vicinity of equilibrium states can be analyzed by linearized approaches. However, motions in transient regimes and unsteady environments require implementation of nonlinear and fully unsteady modeling methods.
Ride Severity Index: A Simplified Approach for Comparing Peak Acceleration Responses of High-Speed Craft
Authors: Riley Michael R. , Coats Tim , Haupt Kelly , Jacobson Donald
Published: January 2021

This article presents a simplified approach to quantifying the comparison of acceleration responses of high-speed craft in rough seas. Statistical acceleration values, used to characterize craft seakeeping responses, including average of the highest one-third, one-tenth, and 1/100th peak accelerations and the root mean square acceleration, are used to define the relative Ride Severity Index (RSI). The article first summarizes an unambiguous computational procedure for multiple investigators to calculate similar acceleration values. It then explains the theory and rational for relating statistical acceleration ratios to an indication of potential damage, whether resulting from cumulative wave impacts or single severe slam events, that can be used in comparative assessments of structural integrity, equipment susceptibility to malfunction, or personnel comfort and safety. Example ride severity comparison plots and computed values of RSI are presented to illustrate the simplicity of the approach and to demonstrate the ability to quantify what heretofore has relied primarily on the subjective experience of operators.
Block Erection Sequencing in Shipbuilding With General Lifting and Joining Times
Authors: Tokola Henri , Niemi Esko , Remes Heikki
Published: January 2021

This article studies the scheduling of block erection in shipbuilding. A mathematical model is formulated to minimize the make span, i.e., the time between the start and finish of the erection schedule, when there are different lifting and block joining times. Structural stability and the no-skipped-blocks property are taken as constraints. The model is used to study the erection in three special cases. First, the case with a short lifting time is analyzed. Second, a solution is constructed for the case in which joining times are short and, third, the case in which the lifting and joining times are the same is analyzed. The article shows how these three cases can be solved efficiently, and, in addition, it gives insight into the erection scheduling such as the effects of the number of blocks in the horizontal and vertical directions on different joining times.
Analytical Approach to a Two-stage Queuing Network for the Planning of Outfitting Processes in Shipbuilding
Authors: Dong Fang , Deglise-Hawkinson Jivan , Van Oyen Mark P. , Singer David J.
Published: January 2021

As an important part of shipbuilding, outfitting can represent a major portion of the material cost as well as the construction time of a vessel. However, as a result of disturbances caused by unexpected delays, system variations, and technological constraints, scheduling of outfitting processes is therefore complex and can lead to major construction delays. To improve the shipbuilding system efficiency in the presence of variation, a two-stage strategic-level outfitting planning model has been developed. The results of the model provide the optimal percentage of outfitting work that should be completed at each stage given the introduction of variation. The model presented can be used as a benchmark for current ship-outfitting management decisions.
The Potential Conversion of the U.S. Great Lakes Steam Bulk Carriers to Liquefied Natural Gas Propulsion: Final Report
Authors: Parsons Michael G. , O' Hern Patrick J. , Harkins Richard W. , Denomy Samuel J.
Published: January 2021

The feasibility and potential benefits of converting 10 remaining U.S. flag Great Lakes steamship bulk carriers to liquefied natural gas (LNG) propulsion using gas engines is investigated. This is the final report of a study that was initially reported at the February 24, 2012, SNAME Section Meeting in Cleveland, OH. The evolving marine air emissions standards and the movement to LNG fuel in U.S. and international non-LNG carriers and the general case for the possible conversion of the remaining U.S. flag Great Lakes steamship bulk carriers to LNG fuel were outlined in the initial report. In this sequel, the final results of a conceptual design study on the conversion of the three AAA class vessels (SS Arthur M. Anderson, SS Cason J. Callaway, SS Philip R. Clarke), focusing primarily on operational and arrangement feasibility and remaining life-cycle economics, are presented. Three cases, a pure diesel conversion, a single fuel LNG conversion, and a dual-fuel LNG/diesel conversion, are compared.