bluuebunny/crossref_metadata_2025 huggingface dataset:
Shaft Line Whirling Vibrations: Effects of Numerical Assumptions on Analysis Results
Authors: Murawski Lech
Published: January 2021

Whirling (lateral, transverse, bending) vibration of a typical marine power transmission system is not usually dangerous for a shaft line. Nevertheless, the shaft line lateral vibration analysis is quite often performed, especially for a long, elastic shaft line or when a ship hull is elastic compared to the propulsion system (Camisetti 1982). Whirling vibrations are transferred to the ship hull through journal bearings and may be a source of excessive superstructure vibrations. During whirling vibrations analysis, some parameters have to be checked. Usually, a beam model of the power transmission system is isolated from the ship hull. Therefore, determining the correctness of the boundary conditions is one of the most important, difficult, and debated tasks. In the author's opinion, stiffness and damping characteristics of the journal bearings' oil film, ship hull, and bearings frame should be taken into account (Murawski 2001). Additionally, the influence of the gyroscopic force and thrust force on whirling vibrations is discussed. The presented numerical analysis method is compared and verified by measurements on real ships.
Frequency-Domain Analysis for Prediction of Seasickness on Ships
Authors: Esteban Segundo , Giron-Sierra Jose M. , Recas Joaquin , De la Cruz Jesus M.
Published: January 2021

Oscillatory vertical motions of ships cause seasickness. There is a mathematical model that can be used to compute the percent of passengers who will get sick caused by vertical motions. However, the application of the mathematical model requires obtaining 2 hours of records of experimental or simulated ship motion data. Based on a filters analogy, this article proposes a new frequency-domain method for the calculation of seasickness incidence. The method can be applied to any sea power spectrum and any ship. Because it is based on response amplitude operators or transfer functions, which can be obtained with seakeeping simulation programs, the method can be applied even before the ship is built. The results of the method can be useful for ship design and for the analysis of best operation for passenger comfort.
Operation of Ships in Cold Climates With Emphasis on Tankers and New Requirements
Authors: Magelssen Wilhelm
Published: January 2021

This paper evaluates the Baltic Ice Rules developed by the Swedish/Finnish authorities and compares them with the Rules given by the Russian Register of Shipping, the Arctic Rules given by Det Norske Veritas, and voluntary requirements given in the Rules for Design Ambient Temperature (DAT). The DAT notation includes requirements for materials with special regard to the possibility of brittle fracture. The DEICE notation gives information on how to solve the icing problem. The paper also touches on areas not covered by the Rules, including icing due to splash from green water, distribution of damage due to ice, and a summary of proposals for designing a ship intended to operate in cold climates.
Industry Guidelines for the Forensic Investigation of Marine Incidents
Authors: Ruggieri James Angelo
Published: January 2021

Landmark court decisions concerning admissibility of expert testimony indicate that industry guidelines and standards are an appropriate source in the formulation and defense of expert opinions. When properly applied, such guidelines and standards provide experts with ample support in adversarial arenas. Review of the court's responsibility to determine scientific basis and expert opinions resulted in the Daubert decision (Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 [1993]). This Supreme Court decision recognized the importance of the "scientific validity of the principles that underlie a proposed sub-mission" as the most critical item the trial judge must evaluate. Furthermore, the Daubert decision established the trial judge's duty to make a preliminary assessment pursuant to Federal Rule of Evidence 104(a) "of whether the reasoning or methodology underlying the testimony is scientifically valid." Many lawsuits involving injuries, deaths, or product defects rely on expert opinion. Thus, the reliability of experts, and the validity of the methodology used by the experts in arriving at their conclusions, must be carefully evaluated. It has been shown that the processes governing the development of industry guidelines and standards address these factors (Ruggieri 2004), providing a sound basis for expert opinions where such guidelines exist and are used. Although there are a growing number of development activities producing such guidelines and standards for land-based incidents, there is little in the way of corollary activities specifically addressing the marine arena. Many of the methods and investigative protocols identified in these land-based guidelines and standards can be made marine applicable; however, substantive technology, operational, and regulatory differences between the land-based and marine paradigms indicate that marine-specific guideline documents are needed for marine applications.
The Friction Between Car Tires and Decks Under Ship Motions
Authors: Jia Junbo , Ulfvarson Anders
Published: January 2021

For roll-on/roll-off (RO/RO) ships, when transporting more cars within the same deck area on board, it is necessary to adjust or take away the current lashing system. Furthermore, this operation may also decrease the cost and time of operation as well as cargo damages due to lashing. This requirement, combined with the safety consideration on cargo shifting, may lead to concepts of lashing-free deck design. One of the lashing-free concepts suggests that in some conditions cars can be secured without using lashings, mainly depending on the friction between the tire and the deck without lashings. By doing a series of parametric studies of vehicle securing without lashings under roll and pitch motions, it was found that the value of the maximum required friction coefficient between the tires and the deck is highly relevant to the roll and pitch amplitude, pitch period, orientation of vehicles on decks, and the vertical location of vehicles from the baseline of the vessel.
Contribution to “An Investigation Into the Loss of the Steel Bark Admiral Karpfanger ex L’Avenir”
Authors: Ünsalan Deniz
Published: January 2021

One of the unsolved marine catastrophes of the past is the loss of Admiral Karpfanger ex L'Avenir in 1938. In a paper published in the October 2004 issue of MARINE TECHNOLOGY, Roger Ghys and Neil W. Cormack discussed possible causes of the disaster. The present paper discusses a phenomenon that came into attention quite recently, which might have been the cause of the loss: parametric resonance of the rolling motion by head or stern waves. Following a short discussion of that phenomenon, the paper concludes that the vessel might have capsized and sunk as the result of parametric resonance.
Multicriterion Optimization of Stern Flap Design
Authors: Parsons Michael G. , Singer David J. , Gaal Christopher M.
Published: January 2021

Stern flaps have been used in many recent designs of transom stern vessels to provide increased top speed or to realize improvements in fuel economy over the operating range. The use of stern flaps has also become a practical retrofit on existing designs because significant improvements can be achieved at very minimal cost. Model test data from a limited series of stern flap designs for a group of combatant type vessels were utilized to develop a preliminary design model for stern flaps for these vessels. This model has been incorporated into Visual VB/Microsoft Excel-based software that will permit the investigation of the benefits of stern flaps in preliminary design. Within the limitations of the model, this software will also perform the multicriterion optimization needed to establish the initial parameters for a stern flap in preliminary design. This preliminary design can become the baseline design for use in a subsequent model test program. The software will then accept the results of tests of a systematic stern flap family developed about the baseline design and create a project-specific response surface model that can be used in subsequent detailed design. The software can then be utilized again to provide multicriterion optimization of this project-specific model to establish final design parameters for the stern flap.
An Overview of the Minisymposium on Extreme Ship Dynamics Presented at the 2005 SIAM Conference on Applications of Dynamical Systems
Authors: McCue Leigh , Alford Laura , Belknap William , Bulian Gabriele , Delorme Louis , Francescutto Alberto , Lugni Claudio , Troesch Armin , Vakakis Alexander
Published: January 2021

This paper provides an overview of the work presented during the two-part minisymposium on Extreme Ship Dynamics at the 2005 Society for Industrial and Applied Mathematics (SIAM) Conference on Applications of Dynamical Systems held in Snowbird, Utah, from May 22 to 26, 2005. The topics covered included theoretical and experimental treatments of seakeeping, capsize, general oscillators, parametric roll, and hydrodynamics. A roundtable discussion focused on means to validate numerical simulation tools.
An Improved Lifting Line Model for the Design of Marine Propellers
Authors: Celik Fahri , Guner Mesut
Published: January 2021

This paper describes a procedure for the design of marine propellers where more realistic representation of the slipstream shape by the trailing vortex system is taken into account. The slipstream shape behind the propeller is allowed to deform and to align with the direction of local velocity, which is obtained by the sum of the inflow velocity and induced velocities due to the trailing vortices. In classical lifting line approaches, that deformation is neglected. Applications for an autonomous underwater vehicle (AUV) and a fishing vessel are carried out to demonstrate propeller design and the effect of the slipstream contraction. Furthermore, a computational fluid dynamics (CFD) analysis based on the finite volume method and experimental validation of the method are carried out for the propellers. CFD analysis and experimental results are compared with the results obtained from present method.
Passenger Vessels for the New Millennium: The Environmental Impacts of the Future San Francisco Bay Area Water Transit Authority Ferry System
Authors: Culnane Mary Frances
Published: January 2021

Technology has transformed the San Francisco Bay region. Silicon Valley and the biotech industry produced plenty of high-paying positions that inflated the economy and created traffic congestion of immense proportions. Growth projections show 1.2 million new Bay Area jobs and a 1.4 million population increase during the next 25 years, accompanied by a 30% increase in region-wide travel and a 40% increase in transbay travel. In an effort to counter the negative aspects of an immobile and consequently less productive commuter society, the California State Legislature created the San Francisco Bay Area Water Transit Authority (WTA) with a mandate to improve public transit with an environmentally friendly ferry system.
Forced Rolling Trials On Board a Portuguese Navy Frigate
Authors: e Silva S. Ribeiro , Pascoal R. , Rodrigues B. , Soares C. Guedes
Published: January 2021

The experimental results obtained during forced and transient rolling trials on board a frigate with active roll stabilizers are presented and discussed. Full-scale experimental data collected at different fin oscillating frequencies and ship advance speeds were recorded and processed in order to obtain transfer functions for the ship and the fin servos. Viscous roll damping coefficients and the ship's natural roll frequency were also calculated from free roll decay curves at different advance speeds. From these trials it was possible to identify open-loop operational parameters of the roll stabilization system, which can be used on a simulation and prediction model.
Limit State Design Technology for a Membrane Type Liquid Natural Gas Cargo Containment System Under Sloshing Impacts
Authors: Paik Jeom Kee
Published: January 2021

The aim of the present paper is to develop limit state design technology for cargo containment system structures of membrane type liquid natural gas (LNG) carriers, with the focus on sloshing impacts. The mechanical properties of plywood material making up the NO96 type LNG cargo containment insulation box structures are obtained from tensile coupon testing undertaken in the present study. The ultimate strength characteristics of the LNG cargo insulation box structure under quasi-static pressure action are investigated using ANSYS computer code. The dynamic failure behavior of the insulation box structure under sloshing impacts is examined using LS-DYNA3D computer code. Some important parameters, such as peak pressure and pressure duration time, which affect dynamic failure behavior, are varied in the LS-DYNA3D computations. The limit state design criteria for the insulation box structures under sloshing impacts are developed. Problem areas to be resolved are discussed.
Ventilation of Controllable Pitch Thrusters
Authors: Ruth Eivind , Smogeli Øyvind N.
Published: January 2021

In oil and gas exploration and exploitation, many ships and rigs conduct station-keeping operations by the use of dynamic positioning (DP) systems or thruster-assisted position mooring (PM) systems. Such systems use thrusters to control the ship or rig position and heading. In severe weather conditions, thrusters may experience large and rapid changes in the propeller loading due to ventilation and in and out of water effects. To reduce the negative effects of this undesired dynamic loading on the mechanical components and the electrical power plant, the thruster controllers can locally compensate for the disturbances. To be able to design and verify such controllers, a model of the losses is needed. In this paper, experiments with ventilating controllable pitch propellers are presented. The results are used to develop a ventilation model for use in simulations. The model is verified by comparing simulations with time series from experiments. Scaling laws for ventilating propellers are also discussed.
Finite Element Analysis of Top-Hat–Stiffened Panels of Fiber-Reinforced–Plastic Boat Structures
Authors: Eksik Ömer , Shenoi R. Ajit , Moy Stuart S. J. , Jeong Han Koo
Published: January 2021

This paper describes the development of a finite element model in order to assess the static response of a top-hat-stiffened panel under uniform lateral pressure. Systematic calculations were performed for deflection, strain, and stress using the developed model based on the ANSYS three-dimensional solid element (SOLID45). The numerical modeling results were compared to the experimental findings for validation and to further understand an internal stress pattern within the different constituents of the panel for explaining the likely causes of the panel failure. Good correlation between experimental and numerical strains and displacements was achieved.
Survival Criteria for Passenger Roll-On/Roll-Off Vessels and Survival Time
Authors: Pawtowski Maciej
Published: January 2021

The paper addresses the problem of damage stability criteria with reference to survival time, that is, the time available for evacuation of passengers on a damaged passenger roll-on/roll-off (RO/RO) vessel undergoing large-scale flooding on the car deck. The current various proposals at the International Maritime Organization (IMO) for the s factor (probability of surviving a given flooding) make no reference to survival time. The paper shows a direct link of the "prime" s factor with the time to capsize. This link has unprecedented value for a flooding control decision support system used during a crisis on board passenger ships but is of no value for the designer for whom the s factor means simply probability of surviving with adequate survival time. The paper shows how to utilize experimental data from 30-minute test runs for survival criteria based on longer duration of tests.
Inclusion of Whisker Spray Drag in Performance Prediction Method for High-Speed Planing Hulls
Authors: Savitsky Daniel , DeLorme Michael F. , Datla Raju
Published: January 2021

The planing hull performance prediction method published by Savitsky in the October 1964 issue of SNAME's Marine Technology included only the viscous drag and pressure drag components in the bottom area aft of the stagnation line. While discussing the existence of an additional component of viscous drag in the whisker spray region forward of the stagnation line, a method to quantify this drag component was not developed in Savitsky (1964). Earlier studies by Savitsky and Ross (1952) and Savitsky and Neidinger (1954) discuss the potential whisker spray drag component but do not present a complete analytical derivation of its magnitude nor verification of the results by comparison with experimental data. The present study fills this void by developing a method for quantifying the whisker spray contribution to total hull resistance as a function of deadrise angle, trim angle, and speed, and incorporating the results into the SNAME published hull performance prediction method. The analytical results are compared with data from model tests conducted at three separate towing tank facilities and show fairly good agreement with these data. It is shown that for high-speed planing hulls, the whisker spray drag component can be as much as 15% of the total drag. In addition, (1) procedures are provided for the proper location, size, and geometry of spray strips to deflect the whisker spray away from the hull bottom; (2) the aerodynamic drag of the hull cross-sectional area above the waterline is also quantified and included in the final performance prediction method; and (3) the equilibrium trim angle identified in the prediction program (for prismatic hull forms) is, for nonprismatic hulls, related to the trim angle of the v4 buttock line (relative to the level water surface) when measured at the forward edge of the mean wetted length.
A Test of the Efficacy of a Ballast Water Treatment System Aboard the Vessel Coral Princess
Authors: Wright David A. , Dawson Rodger , Orano-Dawson Celia E. , Moesel Sharon M.
Published: January 2021

Tests of the efficacy of a combination filtration/ultraviolet (UV) ballast water treatment (BWT) system were conducted aboard the MV Coral Princess during normal operations from Victoria, British Columbia, through the Panama Canal, to Fort Lauderdale, Florida. Trials were designed to assist the maritime industry in the deployment of effective BWT systems and to inform regulatory agencies on the feasibility of testing procedures and end-point selection for compliance standards. Results showed treatment efficacy at least equivalent to ballast water exchange, although adjustment of current published standards was indicated.
Shipboard Trials of Menadione as a Ballast Water Treatment
Authors: Wright David A. , Dawson Rodger , Orano-Dawson Celia E.
Published: January 2021

Shipboard trials of a chemical ballast water treatment, menadione (methyl 1,4-naphthoquinone), were conducted in Baltimore Harbor, Maryland, under normal ballasting conditions at a flow rate of 340 tonne h002D1. Several different concentrations and formulations of menadione were tested. Most proved effective at controlling zooplankton to international standards at approximately 2 mgL002D1 and completely inhibited the growth of phytoplankton at this, or lower, concentrations.
Establishing the Economic and Environmental Life-Cycle Costs of Marine Systems: A Case Study From the Recreational Craft Sector
Authors: Landamore Melanie , Birmingham Richard , Birmingham Richard
Published: January 2021

This paper presents a robust methodology for the investigation of economic and environmental costs within a marine system. It describes the methods used to establish system life-cycle costs, and compares them with their environmental effects to establish the cost-benefit of reducing environmental hazards (Landamore et al. 2006: Life Cycle and Cost Benefit Analysis of Selected Technologies for Sustainable Inland Boating, Newcastle University, January). The case study is a small inland charter boat, operating on the Norfolk Broads, with varying options for powering, hull material, and graywater (GW) treatment. The principles described in this paper can be used to guide the efficient, cost-effective design of any system along sustainable principles. Environmental life-cycle analysis is performed, and the economic cost of each alternative is established. The results presented in the paper show that the majority of systems are cost effective for reducing environmental impact. In addition, a number of systems can be implemented without extra cost, though it is demonstrated that the high cost of the most environmentally effective technologies makes them an inefficient use of resources.
The Effective Use of Experimental and Numerical Data for Validating Simplified Expressions of Stiffened Steel Panel Ultimate Compressive Strength
Authors: Paik Jeom Kee
Published: January 2021

To study the accuracy of simplified formulations for prediction of the ultimate strength of longitudinally stiffened panels under uniaxial compression, the preferred approach is to compare them with available experimental data or numerical results from more sophisticated analysis procedures. Such studies are necessary in the development of both design code calibrations and reliability analysis procedures. Existing experimental data and numerical results useful for this purpose are first collected. Salient features of existing design formulations for compressive strength are then reviewed. Selected formulations are compared with the experimental data/numerical results. It is illustrated that there can be a significant amount of scatter in strength estimates by any one formulation and among formulations. The reasons for such scatter are discussed, with the emphasis on the collapse mode(s) involved, the effective width of plating, initial imperfections, and rotational restraints due to stiffening. The experimental and numerical strength data collected are documented for convenience of future use by other investigators.
Research the Virtual Assembly Multimedia Ship Construction Information System
Authors: Wu Ying-Han , Huang Mei-Xin , Shaw Heiu-Jou
Published: January 2021

This research proposes to build a "Multimedia Ship Construction Information System" to integrate the information of ship design and construction with the implementation document. The system exploits the characteristics of XML to present the electronic implementation document, and thus the information can be used repetitiously. It will then further develop into an extensible and reconstructible script language for the process script of ship construction. It integrates the virtual reality technology and establishes a mechanism that transforms text description into virtual assembly. A three-dimensional (3D) solid model of ship component built previously can be reused, and through the virtual assembly the visualization of implementation process simulation and planning can be conducted. Human intuition is used to present the construction information of the ship so that documents can be transformed from two-dimensional to three-dimensional form to accelerate the information flow on shipbuilding. With relational database technology, a multimedia (text and image) database on ship design and shipbuilding will be established through product data management (PDM), whose function is to control and manage documents to raise the value of information utilization. Moreover, the establishment of a wireless network not only can solve the communication problem between the internal shipyard and the construction site, but also assists the constructors to build the ship correctly, significantly elevate the quality of construction, and increase the working efficiency.
Reanalysis of Ice Pressure-Area Relationships
Authors: Daley C. G.
Published: January 2021

In the polar regions of the world, ships and offshore structures may be subject to impacts with large ice features. Pressure-area models are commonly used to determine both local and global ice loads. A general description of the two types of ice pressure-area models is given. Reanalysis of data from the trials on the USCGC Polar Sea suggests rising average pressure with rising contact area, quite the opposite of the expected result. A quick review of other ice pressure data lends support to the hypothesis. The paper concludes with a discussion of the implications and needed research to improve our understanding of ice loads.
Climate Change Impact on Canadian Northern Shipping Regulations
Authors: Kubat Ivana , Gorman Robert , Collins Anne , Timco Garry W.
Published: January 2021

The objective of this study was to find what effect climate change would have on the Zone-Date System (ZDS). The paper presents an analysis of ice conditions in the Northwest Passage (NWP) shipping lanes and the access routes to the Port of Churchill in the Hudson Strait. The analysis examines the existing and potential changes to ice regimes in the NWP shipping lanes due to the impact of climate change. The length of the shipping season in the NWP is analyzed for each zone by both the ZDS and the Arctic Ice Regime Shipping System, and both systems are then compared. This paper discusses the results of the analysis.
The Ship Track Keeping With Roll Reduction Using a Multiple-States PD Controller on the Rudder Operation
Authors: Fang Ming-Chung , Luo Jhih-Hong
Published: January 2021

The paper presents a nonlinear hydrodynamic numerical model with multiple-states proportional-derivative (PD) controllers for simulating the ship's tracking in random sea. By way of the rudder operation, the track-keeping ability of the PD controller on the ship is examined using the line-of-sight (LOS) guidance technique. Furthermore, the roll-reduction function using the rudder control is also included in the PD controller. From the present simulation results, the single-input multiple-output (SIMO) heading/roll PD controller including LOS technique developed here indeed works, either for the roll reduction or for track keeping while the ship is maneuvering in waves.
Experimental and Numerical Study on the Collapse Strength of the Bulbous Bow Structure in Oblique Collision
Authors: Yamada Yasuhira , Endo Hisayoshi
Published: January 2021

The purpose of this paper is to investigate the collapse strength and the mechanism of the bulbous bow structure in case of an oblique collision. In this study, quasi-static experiments were conducted using two types of large-scale bulbous bow models using the scenario that a ship collides with another ship at oblique angle. One of the models is a prototype buffer bow adopting a transverse stiffening system, and the other model is a standard bow adopting a longitudinal stiffening system. Each model was collapsed by a thrusting rigid board while being subject to the combined action of compressive force and bending moment. Collapse mechanism, load-displacement curve, and energy absorption capability of the buffer bow structure were investigated as compared with those of standard bow structure. Nonlinear finite element analysis (FEA) corresponding to the experiments was also conducted, and fairly good agreement was achieved between FEA and the experiments. It is also found from these investigations that the buffer bow structure is expected to be efficient in reducing the risk of an oil spill, especially in case of oblique collision.
Performance of Buffer Bow Structure against Collision—On the Effect in Preventing Oil Outflow
Authors: Endo Hisayoshi , Yamada Yasuhira
Published: January 2021

The critical striking velocity (VBcr) and the critical collision angle (θcr) are introduced as the measures to represent the performance level of buffer bow. Those critical events are defined as the threshold whether the inner hull of struck tanker is ruptured or not, and they are determined through a series of finite element method (FEM) simulation analyses. Then the effectiveness of buffer bow is highlighted by focusing on the performance how much the risk of oil outflow is decreased. The risk of oil outflow is represented by "the mean oil outflow," which is derived based on a probabilistic procedure considering possible dangerous collision scenarios. The case study has shown that the probabilistic oil outflow is decreased by about 80% if buffer bow design is adopted to very large crude carrier (VLCC).
On the Impact of the Operational Profile on the Ideal Design of a Diving Support Offshore Construction Vessel
Authors: Hovland Erlend
Published: January 2021

Simplified technical and economical analysis of a total of 12 different ship designs has been performed and compared with operational profiles of typical North Sea Diving and Construction vessels. Evaluation of what impact changes to the operational profile has on the best-suited vessel for the operation has also been performed. The paper focuses on optimizing the design to achieve a maximum of days in operation working day. Nomenclature
Some Recent Developments in Corrosion Assessment and Management for Steel Ships and Offshore Structures
Authors: Paik Jeom Kee , Thayamballi Anil K. , Melchers Robert E.
Published: January 2021

While it has been reportedly recognized that most casualties of marine structures including total losses have involved corrosion degradation, corrosion is one of the most important factors influencing safety and integrity of aging structures. Corrosion wastage also causes significant issues in terms of health, the environment, and financial expenditure. While the loss of a total system typically causes great concern, maintenance and repair of damaged structures is costly to society and the environment in general and important to the economic viability of the enterprises involved in particular. It is thus essential to develop advanced technologies that can allow for the proper assessment and management of corrosion. An overview of some recent developments in corrosion assessment and management for steel ships and offshore structures is addressed in the present paper. Relevant corrosion mechanisms, corrosion wastage models, design considerations (design corrosion-margin values), and preventive measures with the emphasis on marine structures are presented.
Structural Reliability Assessment of Aging Ships Using the Concept of Level of Certainty
Authors: Yuen D. Z. , Ivanov L. D. , Wang G. , Choo Y. S.
Published: January 2021

The input data in strength calculations (e.g., loads, geometric, and material properties) may have different levels of certainty/uncertainty. In most cases, the level of certainty of the result (e.g., stresses) is unknown. The knowledge of this certainty is important for all parties involved in ships' design, construction, and operation. In some sense, it indicates the likelihood of the calculated result to happen. When the probabilistic distribution of the stresses is available, the level of certainty of any calculated stress can be determined. However, deriving this distribution is not always possible. Therefore, an approximate method for its assessment is proposed that does not require knowledge of the probabilistic distributions of the input parameters or development of new computer programs. It is based on the percentiles of the input parameters calculated from the statistical analysis of the sample of data for each input parameter. This approach is applied for probabilistic assessment of residual plate thickness, hull girder bending stresses, and stresses derived by finite element modeling. It allows more realistic strength analysis especially of old vessels when the statistical data are scarce. Examples are given for 25K dead weight ton (DWT) bulk carrier. Nothing can ever be proved by statistics, one can only show that there is a certain probability that a given hypothesis is not false, which is not the same as showing that it is correct. Prof. Rutger Bennet, University of Gbteborg, Sweden, 1974
Chain Breakers—A Survey of Fatal Ship Accidents With the Event-Chain Method
Authors: Karlsson Ulf , Ulfvarson Anders
Published: January 2021

The ship research project DESSO (Design for Survival Onboard) aims at improving the safety of RO/RO (roll-on/roll-off) ferries. The project was organized in the autumn of 2003 in order to use the research and development resources existing in Sweden, combined with international expertise, for a radical RO/RO concept with a focus on safety. One part in the early stages of this project was to identify chain breakers from previous accidents, that is, something that would have prevented, stopped, or reduced the conse-quences of the incident event, in order to obtain a realistic basis of "working on the right problem." A systematic and in-depth analysis of a few selected significant and well-documented disasters was made using the event-chain method. The identified chain breakers were further categorized and analyzed to find ideas and concepts that would prevent these events from occurring. These efforts were further developed into a method where the graphics of event chains with chain breakers are used in workshops with experts in two stages. In general, it was found that "Management" in most cases was the initial cause of the events. Often, "Management" was also the reason for the continuing or worsening of the events. As such, education/training and stricter routines were found to be the most effective methods for reducing accidents and are at the same time an inexpensive measure to take. This, together with online stability calculations and decision-support systems, would have prevented most of the accidents analyzed in this work.
Experimental Study on the Behavior of a Swimming Pool Onboard a Large Passenger Ship
Authors: Ruponen Pekka , Matusiak Jerzy , Luukkonen Janne , Ilus Mikko
Published: January 2021

The water in a swimming pool on the top deck of a large passenger ship can be excited to a resonant motion, even in a moderate sea state. The motion of the water in the pool is mainly caused by longitudinal acceleration, resulting from the ship's pitch and surge motions. At resonance, there can be high waves in the pool and splashing of water. In this study the behavior of the Solarium Pool of the Freedom of the Seas was examined in various sea states and operating conditions. The motions of the pool were calculated on the basis of a linear seakeeping method, and the behavior of the water in the pool was studied with experimental model tests. A large-scale model of the pool was constructed and fitted to a purpose-built test bench that could be axially moved by a computer-controlled hydraulic cylinder. Water elevation in the pool was measured, and all tests were video recorded. Different modifications of the pool were tested to improve the behavior of the pool. A strong correlation between the longitudinal motion and the behavior of the water in the pool was found.
A Resistance Reduction Study of a Trimaran using Waterline Parabolization
Authors: Calisal S. M. , Vyselaar Dan , Klaptocz Voytek , Goren Omer
Published: January 2021

Waterline parabolization or addition of side bulbs about the ship's midbody can significantly reduce the wave-making resistance of a vessel [Calisal, S. M., Goren, O., and Danisman, D. B., 2002 Resistance reduction by increased beam for displacement-type ships, Journal of Ship Research, 46, 3, 208–213]. These side bulbs are designed to create a wave pattern that interacts with the ship wave system of the hull at the desired speed range. This concept was first successfully tested on a coaster tanker and then extended to the UBC series hull, a series typical of Canadian West Coast fishing vessels. Systematic tow tank experiments revealed that while parabolization decreases the total resistance, the form factor suffered an increase. An integral boundary layer solver and a 2D RANS solver both showed that the increase in viscous resistance was mainly caused by an increase in form drag or viscous pressure drag. The parabolization concept was subsequently extended to a high-speed NPL trimaran to determine whether resistance reduction using parabolic side bulbs could be achieved for a very slender multihull vessel. A Rankine source panel method was used to predict the wave-making characteristics of the trimaran, and an integral boundary layer solver and a RANS solver were used to calculate the viscous drag. A parametric study, varying the size and location of bulbs, was first performed on the center hull to design the side bulb. The study was then extended to the trimaran to evaluate the additional wave interactions caused by the outriggers. Experimental model tests validated the numerically predicted wave interactions, as well as the change in viscous drag. Based on the numerical work, a modified NPL trimaran hull form was designed that reduced the total resistance of the vessel by up to 6% in the design speed range and providing critical additional engine or accommodation space.
Dynamic Modeling of Gas Turbine Rotor Shaft Faults
Authors: Ogbonnaya E. A.
Published: January 2021

Most imminent faults in gas turbines often emanate from the rotor shaft of the engine. Some of these faults that could lead to catastrophe include misalignment, imbalance, crack, and eccentricity. These defects are equally likely to lead to unscheduled downtime resulting in large economic losses to equipment owners. It is against this backdrop that the rotor shaft of a gas turbine system was isolated and used for this dynamic model to reduce downtime. A method of dynamic modeling was used to consider how the aforementioned faults could be addressed at the design stage of the gas turbine engine. Modeling and simulation of the faults were carried out, and the obtained results compared favorably with what theory suggests. It was observed that cracking, as the most prominent rotor shaft fault, could manifest even at a turbine speed of 7,264 rpm (0.18 m for 0.8776 mm/s vibration velocity amplitude). Artificial neural networks (ANN) were then used to validate and link the results together, which also confirmed the authenticity of the work. Also, a Visual Basic program was used in the course of the various simulations adopted for the modeling, with faults being randomized every 3000 ms, and outputs were easily displayed on desktop computer screen. The work therefore showed how an ANN could be integrated into the monitoring of gas turbine rotor shaft defects. In its totality, the monitoring technique metamorphosed into the development of a software codenamed "The MICE" for monitoring essential performance parameters in gas turbine operations.
Ultimate Limit State Performance of 170k Bulk Carrier Structures: Pre-CSR versus CSR Designs
Authors: Paik Jeom kee , Kim Jin Young , Kim Min Soo
Published: January 2021

The objective of the present paper is to evaluate the ultimate limit state (ULS) performance of 170k bulk carrier structures designed by the IACS common structural rules (CSR) method, compared with the similar-class/type bulk carrier structure designed by the IACS pre-CSR method. The ultimate strengths of stiffened plate structures in deck, side, and bottom parts, and hull girders against vertical bending moment, are computed for the two designs, and the resulting computations are compared. ALPS/ULSAP program is used for the ultimate limit state assessment of stiffened plate structures, and ALPS/HULL program is employed for the progressive hull collapse analysis. The insights and developments obtained from the present study are documented.
Human Factors Analysis and the Shipboard Environmental Department
Authors: van Hemmen Hendrik F.
Published: January 2021

COMSEAPRINT Human System Integration (HSI) is used to analyze the effect of reduced crew sizes and increased crew workloads resulting from increased regulatory requirements on oceangoing commercial vessels (as defined as ships with crew between 10 and 30). Most of the increased crew workloads are driven by recent environmental regulations and the analysis indicates that the creation of an environmental department in addition to the traditional deck and engine departments would efficiently address HSI existing and emerging problems on commercial ships.
Numerical Model of Towing Dynamics of a Long Flexible Life Raft in Irregular Waves
Authors: Raman-Nair W. , Millan J. , Power J. , Somoes-Re A.
Published: January 2021

The equations of motion for the coupled dynamics of a long flexible life raft and fast rescue craft in an irregular ocean wave are formulated in two dimensions using the methods of Kane and Levinson (Dynamics: Theory and Applications, McGraw Hill Inc., 1985). The flexible raft is modeled as spring connected lumped masses, and it is assumed that the motion normal to the wave surface is small and can be neglected; that is, the bodies move along the propagating wave profile. The wave forces are applied using Morison's equation for bodies in accelerated flow. Wind loads are similarly modeled using drag coefficients. The equations are solved numerically using the Runge-Kutta routine "ode45" of MATLAB. The numerical model provides guidelines for predicting the tow loads and motions in severe sea states.
A Four-Quadrant Thrust Controller for Marine Propellers with Loss Estimation and Anti-Spin: Theory and Experiments
Authors: Pivano Luca , Johansen Tor Arne , Smogeli Øyvind N.
Published: January 2021

In this paper a nonlinear thrust controller for fixed pitch marine propellers with torque loss estimation and an antispin strategy is presented. The controller, designed to operate in the four-quadrant plane composed by the shaft speed and the vessel speed, is a combination of a thrust controller developed for calm/moderate sea states and an anti-spin strategy to reduce power peaks and wear-and-tear in extreme sea conditions. The thrust controller aims at producing the demanded thrust independently from the propeller losses. The anti-spin algorithm lowers the shaft speed once large torque losses are detected and increases the shaft speed to normal when the loss situation is considered over. The torque losses are estimated with a nonlinear observer. The performance of the proposed controller is validated by experiments carried out in a towing tank.
Surface Wave Contours Associated with the Forebody Wake of Stepped Planing Hulls
Authors: Savistky Daniel , Morabito Michael
Published: January 2021

Results of an extensive series of model tests that define the longitudinal surface wake profiles aft of prismatic hulls having deadrise angles of 10º, 20º and 30º are presented. Empirical equations are developed that quantitatively define these profiles and are in a form that can be easily applied by designers of stepped planing hulls. These equations are applicable for an expected range of variations in trim angle, speed coefficient, and loading coefficient typical for these hulls. A brief introduction to the concept and to the hydrodynamic advantages of stepped planing hulls is presented to orient the reader as to the importance of wake data in their design. Examples are presented that illustrate the application of these wake data for stepped planing hulls with wetted forebody chine to achieve maximum hydrodynamic lift/drag ratios. Finally experimental results are presented that illustrate the potential resistance penalty associated with the operation of chines dry forebodies where the stagnation line crosses the step.
Some Recent Advances and Future Trends in Nonlinear Structural Mechanics for Ships and Offshore Structures
Authors: Paik Jeom kee
Published: January 2021

Ships and offshore structures are frequently subject to various types of actions and action effects during service that may range from the routine to the extreme or accidental. The oceanic environmental phenomena to which such structures may be exposed include freak/rogue waves, impact pressure actions (arising from sloshing, slamming, and green water), collisions, grounding, dropped objects, fire, and explosions. All of these phenomena have highly nonlinear structural consequences that result in geometric and material nonlinearities. Although the identification of both the actions and their effects is equally important in terms of structural design and strength assessments, this paper focuses on the action effects associated with nonlinear structural mechanics and the subsequent analysis of limit states and risk assessment and management. Future trends and further R&D requirements are also addressed. This paper does not offer a literature survey, but rather discusses some of the important issues that relate to nonlinear structural mechanics and analysis.
Gap Effect on Performance of Podded Propulsors in Straight-Ahead and Azimuthing Conditions
Authors: Islam Mohammed F. , Veitch Brian , Liu Pengfei , Akinturk Ayhan
Published: January 2021

This paper presents results of an experimental study on the effect of gap distance on propulsive characteristics of puller and pusher podded propulsors in straight-ahead and static azimuthing open-water conditions. The gap distance is the axial distance between the rotating (propeller) and stationary (pod) parts of a podded propulsor. The propeller thrust and torque, unit forces, and moments in the three-coordinate directions of a model podded unit were measured using a custom-designed pod dynamometer in various operating conditions. The model propulsor was tested at the gap distances of 0.3%, 1%, and 2% of propeller diameter for a range of advance coefficients combined with the range of static azimuthing angles from +20_ to 20_ with a 10_ increment. The tests were conducted both in puller and pusher configurations in the same loading and azimuthing conditions. In the puller configuration, the gap distance did not have any noticeable effect on propeller torque in straight course condition, but had an effect in azimuthing conditions. The propeller thrust and efficiency were also influenced by the change of gap distance, and the effects were more pronounced at high azimuthing angles and high advance coefficients. For pusher configuration, however, the gap distance did not affect the propeller performance characteristics in straight-ahead and azimuthing conditions. Both in straight course and azimuthing conditions, the unit thrust and efficiency were not influenced by the gap distance in either puller or pusher configurations. The gap distance had a noticeable effect on unit transverse force and steering moment both in puller and pusher configurations, and both in straight course
Regression-Based Assessment of Shafting Torsional Vibration Key Responses
Authors: Magazinovic Gojko
Published: January 2021

A novel procedure for the assessment of propulsion shafting torsional vibration key responses is proposed in this paper. The procedure is based on the response surface methodology applied to a set of system responses compiled over a selected design space. Design space of 1250 design points comprising the shafting stiffness, propeller, turning wheel, and tuning wheel mass moments of inertia coordinates has been employed to build the first torsional natural frequency, crankshaft peak vibration torque, and shafting peak vibration torque quadratic polynomial approximations. Statistical evaluation performed on a full test set of 2500 design points showed that the mean relative errors of 0.14% for natural frequency, 2.93% for crankshaft peak vibration torque, and 0.41% for shafting peak vibration torque were achieved. Good agreement between the assessed and actual torsional responses stresses the importance and utility of the proposed metamodels for the propulsion shafting preliminary design purposes. An example application based on the 114,000 dwt tanker propulsion shafting is also provided.