bluuebunny/crossref_metadata_2025_split huggingface dataset:
Product-Oriented Design and Construction (PODAC) Cost Module – An Update
Authors: Trumbule John C. , Dougherty John J. , Deschamps Laurent , Ewing Richard , Greenwell Charles R. , Lamb Thomas 
Published: January 2021

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

Recently, many container ships have been built worldwide, and the size of them is skyrocketing to 10, 000 TEU (Twenty Equivalent Unit) capacity. As a result, the plate thickness in the area of upper deck torsion box becomes thicker and thicker with higher-strength steel, up to 60 mm, to keep longitudinal strength, and then the welding work becomes more difficult and severe. For such joints of super thick plates IHI Marine United Inc. Kure shipyard has established high-quality and high-efficient welding methods:Development of new steel plates. In order to weld the thicker plates by high heat input such as 450 KJ/cm, new steel plates were applied in cooperation with a steel maker in Japan.Automation of butt welding. Electro-gas arc welding was applied for skin plates, and CO2 welding robot system was also introduced for longitudinals around the torsion box.Establishment of high quality welding practice.
Welding without defects became possible by establishing adequate groove shape and welding procedure, as a result of many welding tests and inspections. This paper describes the improved methods and the test results in detail.
Reduction of Overwelding and Distortion for Naval Surface Combatants, Part 1: Optimized Weld Sizing for Lightweight Ship Structures
Authors: Huang T. D. , Harbison Michael , Kvidahl Lee , Niolet David , Walks John , Stefanick Kevin , Phillippi Mark , Dong Pingsha , DeCan Larry , Caccese Vincent , Blomquist Paul , Kihl David , Wong Rick , Nappi Natale , Gardner James , Wong Catherine , Bjornson Michael , Manuel Allen 
Published: January 2021

As high-strength thin-steel use in ship design increases, dimensional management becomes critical to control construction costs and schedule in ship production. In the U.S. shipbuilding industry, improvements to shipbuilding facilities and processing technology have not kept pace with the rate of change in ship design. Additionally, new designs using thinner steels are subject to legacy weld-sizing criteria, which may inappropriately size welds on lightweight materials. These two factors result in widespread overwelding, causing severe plate buckling in naval vessels during construction. The problem of overwelding has two distinct sources:the weld-sizing methods developed in the 1980s are still used in most shipbuilding specifications regardless of ship class. This prevents the incentive of application of latest technologies that can make strong, precision fillet welds for modern lightweight thin steel naval surface combatants; andshipyard welders tend to make welds even larger than design requirements to satisfy naval production specifications, which do not allow for any undersized welds.
On average, production welds are 3 mm larger than design, which can more than double the heat input and distortion caused by welding. The approach to the solution of this overwelding problem will be described in detail in this article:develop appropriate weld-sizing criteria for thin plate structures; this can be facilitated by numerical modeling to ensure adequate static shear, tensile, bending, fatigue, and dynamic impact capacity of structural welds; andperform a robust designed experiment to establish confidence that small weld sizes can provide necessary performance and strength to meet the design service life of the vessel and provide data to NAVSEA technical warrant holders to support the implementation of an underweld tolerance for ship production to prevent overwelding.
Weld Residual Stress Measurement on Ship Structures
Authors: Yang Yu-Ping , Huang T. D. , Scholler Steve , Dull Randy , Fisher Charles R. , Zhang Wei 
Published: January 2021

Weld residual stresses on ship structures were significantly investigated by using a three-step approach. Step 1 is to measure residual stress on small samples in laboratories to validate measurement methods, step 2 is to measure residual stress on three test panels made of DH36, HSLA-65, and HSLA-80 in a shipyard, and step 3 is to measure residual stress on a large mock-up unit and on a tie-down. Step-1 and step-2 study, presented in the Society of Naval Architects and Marine Engineers-2017 conference, concluded that portable X-ray equipment can be used in a shipyard environment to provide reliable measurements. Residual stress was successfully measured on small welded joints, the DH36 panel, and the HSLA-65 panel, but not on the HSLA-80 panel. The reason for poor measurements on the HSLA-80 panel was that the primer on HSLA-80 surfaces blocked the diffracted X-ray. To achieve a good measurement, mechanical grinding and electropolishing were investigated to remove the primer before measurement. The minimum electropolishing time required to remove the compressive stress induced by mechanical grinding was established by experimental trials. With the electropolishing process, reasonable measurements were achieved on the HSLA-80 panel, a tie-down, and the knuckle joints of the large mock-up unit. This study reports the measured stresses on the HSLA-80 panel, the tie-down, and the knuckle joints.
Welding, as one of the most important manufacturing processes in shipbuilding, inevitably induces residual stress and distortion on ship structures. Multiple methods have been developed to measure residual stress with nondestructive and destructive techniques. The common nondestructive techniques include X-ray diffraction (XRD) (Gou et al. 2015; Bandyopadhyay et al. 2018; Monine et al. 2018), neutron diffraction (Palkowski et al. 2013), magnetic method, ultrasonic methods (Bray & Junghans 1995), and impact-indentation method (Zhu et al. 2015). The destructive techniques include hole-drilling and ring-core methods, and the destructive techniques include block removal, splitting, layering, and contour methods (Leggatt et al. 1996).
Smart Bearing Sensor
Authors: Leontopoulos Chris , Mouzakis Charalampos , Petrolekas Michail 
Published: January 2021

The recent increase in vessel shaftline bearing incidents indicates that a static shaft alignment design may not be suitable for all operational shaftline loading conditions. Hull deflections caused by vessel loading or propeller loads initiated by interaction with the wakefield have become important considerations in modern vessel design. Jack-up tests, typically used as a bearing load verification method, can only be accomplished under static shaft conditions and cannot verify the shaft dynamic behavior under running operational conditions. A newly developed sensor using strain gauge technology measures the bearing load and the shaft misalignment angle through the bearing housing's deformation-induced strain. It effectively converts the bearing housing into a weighing machine by mapping the bearing housing strain onto the bearing load. Unlike jack-up tests, this method allows for the continuous measurement of the bearing load and misalignment angle under all shaftline operational conditions. It is envisaged that this technologically simple system will allow for the earliest possible diagnosis of shaft alignment-related problems, such as bearing unloading, bearing overloading, or excessive shaft-bearing misalignment. This provides a much earlier warning indicator when compared with the bearing temperature alarm. The subject technology has been tested on intermediate bearings and is considered for future application into stern tube bearings.

1. Introduction
In post-IMO's (International Maritime Organization) Energy Efficiency Design Index vessel designs, the propulsion shafting arrangements become increasingly sensitive to shaft alignment with lower tolerances and margins, increasing the risk of stern tube bearing failures (Leontopoulos 2016a). This change is due to the wider use of more efficient, larger diameter propellers with increased cantilevered load on the shafting system and shorter shaftlines as a result of maximizing cargo space and minimizing engine room length. Widespread application of the single stern tube bearing design (an arrangement without a forward stern tube bearing) has also highlighted a decreased tolerance to eccentric propeller thrust and propeller forces in general. Reduced tolerance to shaft alignment sighting errors, bearing offset inaccuracies and other shaft installation errors, also affects the integrity of the shafting system and can result in complete bearing wiping with the consequence of vessel propulsion immobilization. This undesirable consequence has increased, particularly during the years 2013–2017.
The Analytical Calculation of Ship Bending Moments in Regular Waves
Authors: Jacobs Winnifred R. 
Published: January 2021

The longitudinal distribution of forces acting on a T2-SE-A1 tanker moving in regular head seas is found by an analysis based on the "strip method" used by Korvin-Kroukovsky in the development of his theory of ship motions, lending moments at the midship section are calculated and compared with bending moments measured during model tests. The theoretical values of bending moments are of the same order of magnitude as those found in the experiments. However, some discrepancies between them appear. These may be due to experimental error as well as to deficiencies in the method of calculation. Certain important facts are brought out by the theoretical calculations:The midship bending moment is virtually a second-order effect dependent on local variations in the longitudinal distribution of the loads.Dynamic bending moments at reasonable speeds are less than those obtained by the conventional static calculation with Smith correction.
This confirms experimental findings.
The Icebreaking Problem in Two Dimensions: Experiments and Theory
Authors: Valanto Petri 
Published: January 2021

Model experiments on the transient response of a floating ice sheet to an advancing icebreaker were carried out in two dimensions in order to provide information on the actual icebreaking phenomenon associated with ships advancing in level ice. The response consists of two parts:the dynamic bending of the ice sheet to flexural failure; andthe rotation of the broken ice slab until the slab is parallel to the bow plate of the advancing vessel.
A theoretical approach to calculate the transient response of the floating ice sheet is presented. The theory is based on the assumption of potential flow with a relatively complicated boundary condition on the ice sheet-fluid surface. The numerical solution is based on an initial-value approach. The kinematic and dynamic boundary conditions on the ice sheet-fluid boundary are used to advance the solution in time. The predicted results are compared to the experimental ones to evaluate the validity of the theoretical assumptions made. In most cases close agreement between experiments and theory is demonstrated. Together with the experiments, the numerical model developed is able to clarify several physical phenomena contributing to icebreaking resistance at the waterline of a vessel advancing in level ice.
Probability of Ship High-Runs from Phase-Space Data
Authors: Kontolefas Ioannis , Spyrou Kostas J. 
Published: January 2021

A clustering scheme has been applied for capturing qualitatively different surge motion patterns in the phase space. The scheme enables the identification of "high-run" incidents as soon as such motions are triggered and while their phenomenology has not yet been well developed. A "high run" is a surf-riding-like behavior, appearing in irregular following seas. The concept of finite-time coherent sets is exploited for deriving estimates of the probability of high-runs. The method is verified by identifying independently the corresponding hyperbolic Lagrangian coherent structures; then, consistency is sought between the two approaches. An important feature of the method is that it does not rely on the use of some empirical criterion for the high-run threshold, such as one based on the exceedance of an arbitrary high-speed level. Despite its computational burden, the proposed scheme offers "objective" statistical information on a ship's high-run tendency that can be used for benchmarking simpler (approximative) probability calculation schemes.

1. Introduction
Current efforts to assess a ship's tendency for abnormal behavior in extreme seas are still limited from our inadequate grasp of the full variety of nonlinear ship motion phenomena that could be realized in an irregular seaway. A classification of these motion patterns would provide a sound basis for developing probabilistic calculation methods of ship operability and safety in extreme seas. A few recent research efforts in our group have been related to this target. In one case, it was endeavored to distinguish ship high-runs from ordinary surging, by engaging the concept of instantaneous wave celerity (Spyrou et al. 2014). In another, the derivation of a practical metric for the probability of high-run was pursued (Belenky et al. 2016). Also, high-run and broaching-to statistics were produced through a direct approach based on assigning prescriptive exceedance thresholds (Spyrou et al. 2016b). Moreover, the theory of surf-riding was extended for bichromatic waves, revealing some rather unexpected types of motion (Spyrou et al. 2018). Even richer phenomena could be conjectured for a multifrequency environment.
An Energy Efficient Autopilot Design
Authors: Tréhin Mathilde , Laurent Johann , Kerhascoët Hugo , Rossi André , Diguet Jean-Philippe 
Published: January 2021

Abstract.
In this paper, we propose a new control method for the next generation of sailboat autopilots. These new systems will need to manage more actuators to control the hydrofoils, which is going to significantly increase the energy requirements. So, this method is aware of the autopilot power consumption. It uses a model predictive controller to manage the actuators. This controller uses a dynamic model of the actuator, running in real time, to anticipate the future behavior of the system. Once the predictions are made, it determines the future control sequence to apply in order to follow the reference trajectory. To do so, it minimizes a cost function which takes into account two criteria: the precision of the system and the energy. With the proposed control method, skippers can focus on one or the other criterion depending on their goals and the boat's energy balance. We apply this method to one of the autopilot's subsystems, namely the rudder control. The electric actuator intervening in this control loop and the load representing the force opposed to its motion are modelled to design the control law. The first results of that method are compared with a standard autopilot. We increase by 40% the precision level and we are able to reduce the consumption by at least 20%. This work provides the first necessary components of a future autopilot that will control the whole appendages to a three-dimensional piloting. Moreover, this type of management is a first step towards possible fossil fuel-free sailboats.
Welding Problems in Shipbuilding
Authors: Masubuch Koichi 
Published: January 2021

During the past 30 years, many new welding processes have been applied to the fabrication of various metal structures. However, these processes have largely been ignored by the shipbuilding industry, and modern ships continue to be fabricated primarily by a manual arc-welding process that is more than fifty years old. This paper discusses some of the problems related to welding ship structures, focusing mainly upon two important subject areas:new welding processes, andnotch toughness of weld metal.
The author reviews briefly developments in the technology and, emphasizing the technical problems, indicates how research can improve the state of the art.
Measures of Merit for Ship Design
Authors: Benford Harry 
Published: January 2021

Abstract
My purpose in writing this paper is to explain the role of engineering economy in ship design and to discuss the relative virtues and shortcomings of the several measures of merit in current use. In particular, I want to compare the two criteria most popular with United States business managers today: net present value and discounted cash flow rate of return, or yield. I also want to make the point that, under some conditions, the required freight rate criterion may be preferable to either of those two. All valid criteria have the characteristic of flat laxity. Therefore, finding an exactly optimal design is not as important as establishing the range of designs that promises close to the maximum level of profitability. Applying the different criteria to a typical speed-optimization study demonstrates that, when properly used, each valid criterion will indicate a design that is within the reasonable range indicated by the others. The effects of taxes as well as bank loans are covered in some detail, with illustrative examples from a feasibility study. These demonstrate that taxes have great influence in weighing the economic merit of new technologies but that bank loans do not. A brief discussion of inflation concludes that technical decisions need be little affected by expected changes in the value of the dollar.
Tension-Leg Platform Design: Interaction of Naval Architectural and Structural Design Considerations
Authors: Capanoglu Cuneyt 
Published: January 2021

As oil exploration and production move into water depths over 1000 ft (305 m), several companies are investigating compliant structures as possible solutions to the economic and engineering problems involved. This paper focuses on the tension-leg type of platform, a positively buoyant structure kept on location by a pretensioned anchoring system. The basic approach to design of a tension-leg platform system, the various components of the system and the interaction between naval architectural and structural design considerations are presented. The author points out that planning for a successful design must include:preparation of good design criteria,determination of variables,evaluation of variables for sensitivity and interaction,accurate and timely engineering decisions in selection of a set of parameters, andparallel studies covering fabrication, transportation and installation requirements.
Appendices give the mathematical bases for computing motions of the tenslon-leg platform and graphic illustrations of platform characteristics and the effects of typical exciting forces.
Experience with Heavy Fuel
Authors: Mori Shigeo 
Published: January 2021

Beginning in the fall of 1973, the oil crisis created a drastic worldwide change in thinking about oil resources. At the June 1979 OPEC meeting in Geneva, the price of oil was raised substantially, to some 20 U.S. dollars per barrel, and further forecasted to zoom up to more than 30 U.S. dollars in 1980. According to our study of a 10 000-dwt cargo vessel, the fuel oil cost—even in 1976—already constituted approximately 50 to 60 percent of the overall operating cost (excluding capital costs). In order to combat this undesirable development, the marine diesel engine is strongly needed to materialize energy savings from every possible angle, and various measures for this purpose have been vigorously advanced. One approach is the use of heavy fuel instead of the more expensive diesel oil, and this paper introduces one company's experiences with this energy-saving method, especially in the following items:Heavy fuel limitations— engine types suitable to burn up to 1500 sec and UE engines up to 3500 sec;engine room fuel system and accessories needed for up to 1500 sec and those for up to 3500 sec;problems still being encountered with heavy fuel;maintenance intervals and wear factors compared with running on diesel fuel; andoperation cost savings.
Finally, an example is given of a slow-speed diesel versus a medium-speed twin engine installation for a pusher tug of less than 300 G/T (tug/barge system).
Experience with Real-Time Motion Monitoring on the Barge Foss 245
Authors: Hutchison Bruce L. , Nichol Robert E. 
Published: January 2021

The shipment by barge of a 240-ton retired steam generating unit from the Surry, Virginia nuclear power plant in the spring of 1980 provided an opportunity to apply modern state-of-the-art motion monitoring and damage-avoidance techniques to a towed ocean barge. This paper reports onthe project background, including prevoyage risk analysis which resulted in the recommendation that real-time motion monitoring be provided;the design and installation of the motion monitoring system; andthe tug master's experience during the voyage with the real-time motion feedback.
The paper concludes by comparing selected motion records from the motion monitoring system to motion predictions based on logbook and hindcast sea-state data. It is concluded that the real-time motion monitoring worked well on the subject barge shipment and achieved the primary objective of providing useful feedback to the tug master concerning the effects of his actions on the barge and cargo. It is suggested that the technique is sufficiently promising to warrant wider use by the offshore tug/barge industry. All sciences are vain and full of errors that are not born of experience, mother of all certainty, and that are not tested by experience…Leonardo
BOAT-2000 Database: Market Study and Aid to Power and Sailboat Design
Authors: Vasconcellos J. M. A. , Latorre R. G. 
Published: January 2021

This paper presents the BOAT-2000 database* organization. Its applications in market study as well as power and sailboats design are used to show the system capability for integrated design. BOAT-2000 is not a commercial system and was created to integrate recreational boat information and commercial design software for academic research. The BOAT-2000 aim is to join in a database the useful information on sail and powerboat design, manufacturers, equipment and test results. The database includes also specific naval architecture software and others functional software's. BOAT-2000 was developed in Microsoft ACCESS™ and follows four main objectives:simple and useful tool for boat market analysis,ability to arrange the design process,includes different sorts of boat information as test results and survey reports, andintegrates commercial softwares in boat design process.
The paper focuses on database systematization and shows the BOAT-2000 application in two case studies. Graphs and tables illustrate the actual available dates. Finally, some future implementations are emphasized.