bluuebunny/crossref_metadata_2025 huggingface dataset:
Displacement of a Deflected Ship Hull
Authors: Ziha Kalman
Published: January 2021

Relevant approximations based on permanent waterplane characteristics are summarized for a more accurate assessment of the effects of longitudinal deflections of an elastic ship's hull on drafts and displacement during marine surveys of merchant ships. The possibility of a different practice for placement of draft marks on a ship's sides, ensuring the same precision in displacement assessment of a deflected and trimmed hull by only two draft observations, is investigated by employing the waterplane properties. Correction factors for conventional ships, based on the waterline coefficient for changes of hydrostatic load, arising due to hull deflections, are also summarized. Example results are demonstrated on a Croatian-built bulk carrier.
Oil Mist and Machinery Space Fires
Authors: Holness Malcolm H. , Smith Brian J.
Published: January 2021

A review is presented of the role of oil mist as a principal agent in machinery space fires. The ways in which oil mist can be produced are described as well as the distinction between mist and spray. The contrast between the oil mist conditions inside crankcases and that in the general atmosphere in machinery spaces is discussed. Methods of measuring oil mist and spray are described and equipment suitable for monitoring conditions inside machinery and in machinery spaces is discussed. Recommendations are made to improve safety on board ship and in industrial plants, and Appendices 1 through 4 cover IMO regulations and other initiatives on the oil mist hazard.
Optimized Design of Small Craft
Authors: Majumder M. , Akinturk A. , Çalisal S.M.
Published: January 2021

The preliminary design of a small craft can be computerized by a formulation based on optimization, and new design nodes such as crew safety or acceleration levels can be included in the preliminary design (Akinturk 1997). In addition, it is shown that an integrated technical computing environment, such as MATLAB, can be used for the preliminary small craft design, and ergonomic criteria can be included in the design process. This design process, referred to in the text as "MATSHIP," can be easily implemented in design offices. In addition to the preliminary design parameters, which MATSHIP calculates, it obtains a new operational parameter for the permissible ship speed in a sea state for a set ceiling level of crew safety.
A Brief Review of Marine and Offshore Safety Assessment
Authors: Wang J.
Published: January 2021

This paper reviews some typical marine and offshore accidents in terms of major causes and resulting actions. The lessons learned from previous marine and offshore accidents are discussed in terms of the change of the safety culture in both the marine and offshore industries. The concepts of initiating events and safety system responses in an accident sequence are described. The provision of risk analysis and prevention of accidents are discussed. The offshore safety case approach and formal ship safety assessment of ships are described in detail. The future aspects in marine and offshore assessment are also discussed.
Predicting Resistance of Spherical-Type LNG Carrier Structures to Ship Collisions
Authors: Paik Jeom Kee , Choe Ick Hung , Rivas Silvia
Published: January 2021

The modern design of steel structures uses limit states classified into four types, namely, serviceability limit state, ultimate limit state, fatigue limit state and accidental limit state. The aim of this paper is to propose and illustrate a procedure to assess the capability of a spherical-type LNG carrier of 135 000 m3 to resist ship collisions. An assessment procedure based on the energy dissipation capability relating to structural crashworthiness can, in this case, be applied to protect spherical LNG cargo tanks from fracture in minor or moderate collision accidents as shown in the paper. In the procedures developed, while the loss of kinetic energy during the collision accident is approximately estimated by applying the momentum equilibrium of the two implicated ships, a series of relatively sophisticated numerical computations is under- taken to simulate the structural crashworthiness of the object ship in the full load condition at standstill, varying the loading conditions and types of the striking ship, when the LNG carrier side structure is considered to be struck by the bow of either a VLCC or another LNG carrier. Based on the computed results, the collision resistance indices (CRI), which in the present study are defined as a function of the ratio of the structural energy dissipation capability to the initial kinetic energy loss, are calculated for the object ship for various collision scenarios. Some important insights useful for preventing collision damage of the spherical LNG cargo tanks of the ship are also discussed.
Stockholm Agreement—Past, Present, Future (Part 1)
Authors: Vassalos Dracos , Papanikolaou Apostolos
Published: January 2021

April 1, 2001 marked the fourth anniversary of the Stockholm Agreement (SA), a period during which almost 80% of the roll-on/roll-off (Ro-Ro) fleet in North West Europe have been subjected to calculations, model testing and numerical simulations in the struggle to meet these demanding new requirements. The experience gained has been invaluable in understanding better the problem at hand and is being utilized to shape new developments likely to lead to more meaningful requirements. The North-South divide, however, continues to cause unrest, particularly at the European level. Efforts to assess the status quo in North West Europe, and to use the information amassed so far as a means to predict the potential impact of introducing the SA in the South, led to a dedicated call by the Commission and to a contract being awarded to two closely collaborating teams, one at the Ship Stability Research Centre of the University of Strathclyde under the leadership of Professor Vassalos and one at the Ship Design Laboratory of the National Technical University of Athens, under the leadership of Professor Papanikolaou, representing the North and South of Europe, respectively. This background provided the incentive for an introspective look at the SA, with a view to ascertaining its status before embarking into future projections. This forms Part 1 of the SA related research with Part 2 aiming to cover the results of the Commission study itself.
Optimal Compartment Layout Design for a Naval Ship Using an Improved Genetic Algorithm
Authors: Lee Kyu-Yeul , Han Seong-Nam , Roh Myung-I
Published: January 2021

With the trend in modern naval ships towards less dense payloads, space layout design has become more important. Recent advances in computing science and increased understanding of methods for developing mathematical models, which form the basis of the space layout design, have helped with the development of a powerful design procedure. In this study, the compartment layout problem, which can be regarded as the space layout design of a naval ship, is represented as a mathematical model, and a compartment layout algorithm based on the genetic algorithm (GA) in order to solve the problem is proposed. Comparative testing shows that the proposed algorithm performs better than other existing algorithms for the optimal compartment layout design. Finally, the proposed algorithm is applied to the compartment layout problem of a naval ship and the computational results are compared with the actual compartment layout of the naval ship.
SNAME Annual Meeting 2001—Additional Discussion to Paper 10 “Hydrodynamic Efficiency Improvements to the USCG 110-Ft WPB Island Class Patrol Boats” by Gabor Karafiath, Dominic Cusanelli, Stu Jessup, and Christopher Barry
Authors: Hackett John P.
Published: January 2021

I would like to thank the authors for a fine paper. As can be seen by the authors' list of references, this paper continues a fine tradition of technical papers on the performance improvements possible for vessels equipped with stern flaps. With this paper the authors have expanded the size range of vessels they have reported on, with the WPB being the smallest.
Full Scale Particle Removal Performance of Three Types of Mechanical Separation Devices for the Primary Treatment of Ballast Water
Authors: Parsons Michael G. , Harkins Richard W.
Published: January 2021

The Great Lakes Ballast Technology Demonstration Project has undertaken a multi-year program to demonstrate and evaluate ballast treatment methodologies that might minimize the potential for the introduction of additional nonindigenous aquatic species into the Great Lakes and other U.S. waters. Full-scale mechanical and biological testing of primary and secondary treatment options has been performed on both operating vessels and a ballast treatment testing barge facility located in Duluth and Two Harbors, Minnesota. Mechanical testing results for three candidate primary mechanical separation devices obtained over a four-year period on the barge installation are presented and compared. Results are presented for the particle removal efficiency at a nominal 340 m3 /h (1500 U.S. gpm) for a 50 micron (µm) screen-type surface automatic backwash filter, a 100 µm rated cyclonic separation device, and a 100 µm disk-type depth automatic backwash filter. The screen-type and disk-type automatic backwash filters showed particle removal efficiencies at and above their removal rating of over 90%. Although more complicated, the disk-type depth filter exhibited a significant advantage through a longer time between backwash cycles and, thus, a greater net filtration throughput. The hydrocyclone demonstrated significantly lower effectiveness (about 30%) in removing particles that included both neutrally buoyant biota and other materials such that, while much simpler, these devices are not considered appropriate for this application requiring the effective removal of both particulate material and larger biota.
Strains and Deflections of GFRP Sandwich Panels Due to Uniform Out-of-Plane Pressure
Authors: Roberts J. C. , Boyle M. P. , Wienhold P. D. , Ward E. E.
Published: January 2021

Rectangular orthotropic glass fiber reinforced plastic sandwich panels were tested under uniform out-of-plane pressure and the strains and deflections were compared with those from finite-element models of the panels. The panels, with 0.32 cm (0.125 in.) face sheets and a 1.27 cm (0.5 in.)core of either balsa or linear polyvinylchloride foam, were tested in two sizes: 183 × 92 cm (72 × 36 in.) and121 × 92 cm (48 × 36 in.). The sandwich panels were fabricated using the vacuum-assisted resin transfer molding technique. The two short edges of the sandwich panels were clamped, while the two long edges were simply supported. Uniform external pressure was applied using two large water inflatable bladders in series. The deflection and strains were measured using dial gages and strain gages placed at quarter and half points on the surface of the panels. Measurements were made up to a maximum out-of-plane pressure of 0.1 MPa (15psi). A total of six balsa core and six foam core panels were tested. Finite-element models were constructed for the 183-cm-long panel and the121-cm-long panel. Correlation between numerical and experimental strains to deflect the sandwich panel was much better on the top (tensile) side of the panels than on the bottom (compressive)side of the panels, regardless of panel aspect ratio or core material. All sandwich panels exhibited the same compressive strain reversal behavior on the compressive side of the panel. This phenomenon was thought to be due to nonlinearly induced micro-buckling under the strain gages, buckling of the woven fabric, or micro-cracking within the resin.
Stena V-MAX: A Total Concept for Safe Oil Transportation in Confined Waters
Authors: Södahl Björn
Published: January 2021

When the first Stena V-MAX vessel, the Stena Vision, entered the Delaware River on her maiden voyage in the summer of 2001 (as this symposium [MEETS01] was being held in Washington) she marked the realization of a project that started almost five years earlier. In October 1996 the 1975-built Stena Constellation made the same voyage up to Philadelphia as the first VLCC ever to dock at the Fort Mifflin terminal. The operation involved a new scenario compared with the normal open-water VLCC trading, and all the parties involved contributed to assess risks and establish safe procedures for the different phases. As the operation developed, so did ideas on an improved ship design which would be better suited to do the job on a year-round basis. This led to a new type of VLCC with wide beam and shallow draft, the V-MAX. Apart from carrying a significantly larger amount of cargo, the V-MAX is also uniquely equipped to cope with the challenges and hazards of the river passage, making oil transportation to Philadelphia both safer and more efficient compared with her predecessors. In the world of today we avoid flying passengers in single-engine aircraft. Similarly we should strive to avoid a situation where a single technical failure on an oil tanker could lead to an ecological disaster. The twin propellers and rudders are the most visible features, which, apart from redundancy against single failures, give the wide hull superior maneuvering characteristics. These and numerous other technical aspects and operational considerations make the V-MAX represent not only a new ship but also a complete concept for safe oil transportation in narrow waters. This paper outlines the background and evolution of the V-MAX concept and describes the specific features which contribute to effectively reduce risk when operating in narrow and heavily trafficked areas.
An Investigation of Head-Sea Parametric Rolling and Its Influence on Container Lashing Systems
Authors: France William N. , Levadou Marc , Treakle Thomas W. , Paulling J. Randolph , Michel R. Keith , Moore Colin
Published: January 2021

In October 1998 a post-Panamax C11 class containership encountered extreme weather and sustained extensive loss and damage to deck stowed containers. The motions of the vessel during this storm event were investigated through a series of model tests and numerical analyses that confirmed the vessel's parametric rolling response in head seas at the time of the casualty. These studies provide insight into the conditions in which post-Panamax container ships are likely to experience head sea parametric rolling, and the magnitude of motions and accelerations that can occur. The findings from this investigation are presented in this paper, together with discussion of how such extreme motions impact the design and application of container securing systems. Also outlined in the paper are recommendations for additional research needed to better understand the influence of vessel design and operational considerations on the propensity of post-Panamax containerships towards parametric rolling. This investigation and other recent studies demonstrate that parametric roll in extreme head or near head seas can occur when unfavorable tuning is combined with low roll damping (reduced speed) and large stability variations (governed by wavelength, wave height, general hull form, bow flare, and stern shapes). Parametric rolling is an unstable phenomenon, which can quickly generate large roll angles that are coupled with significant pitch motions. The rolling occurs in phase with pitch, and on containerships introduces high loads into the containers and their securing systems. It appears that post-Panamax containerships may be particularly prone to this behavior. This is an important issue considering the large number of these vessels scheduled for delivery in the next few years.
Considerations in the Design of the Primary Treatment for Ballast Systems
Authors: Parsons Michael G.
Published: January 2021

Investigations are currently underway to establish effective primary and secondary ballast water treatment methods to minimize the potential for the introduction of additional nonindigenous aquatic species into the Great Lakes and other U.S. coastal waters. This treatment could be used in place of mid-ocean ballast exchange currently required by the U.S. Coast Guard for all vessels entering the Great Lakes in ballast from beyond the Exclusive Economic Zone (EEZ). Primary and secondary treatment could provide environmental protection for both Ballast On Board (BOB) vessels, which are required to perform mid-ocean ballast exchange before entering the Great Lakes, and No Ballast On Board (NOBOB) vessels, which are currently exempt from any ballast exchange requirements. Primary treatment using some form of mechanical separation to 100 urn or 50 um followed by secondary treatment using 254 nm UV irradiation or some form of chemical treatment are currently leading candidates. Over the past six years, the Great Lakes Ballast Technology Demonstration Project (GLBTDP) has undertaken the full-scale evaluation of 340 m3/h (1500 U.S. gpm) ballast water mechanical separation using an automatic backwashing screen filter, hydrocyclone, and automatic backwashing disk filter. This experience provides the basis for the investigation of various ballast system design issues that must be considered in the selection and design of the primary ballast water treatment. This investigation is based upon the ballast system of a typical Seaway size bulk carrier using port and starboard 2000 m3/h (8800 U.S. gpm) main ballast pumps. A discrete multicriterion optimization tradeoff study using the Analytical Hierarchy Process (AHP) is also presented to illustrate a rational method for determining the best choice for primary ballast water treatment for such a Seaway size bulk carrier.
Modular Gas Turbine Propulsors: A Viable Alternative for Today’s Merchant Fleet
Authors: Ackerman Brian M.
Published: January 2021

Gas turbines offer the commercial shipping industry the best power to volume ratio available for a propulsion package. When coupled with a podded propulsor, gas turbines can be placed in a module anywhere on the vessel, allowing optimal use of vessel space for cargo. As the shipping market continues to evolve, modular gas turbines seem to be the logical choice for future vessels. The object of this paper is to demonstrate the substantial increase in profits associated with a modular gas turbine propulsion package.
Parametric Study of the Modulus of Residual Stiffness for Sandwich Beams
Authors: Weissman-Berman Deborah , Jones David E.
Published: January 2021

A sandwich structure is defined by a bi-geometrical structure and substructure related by the modulus of residual stiffness, α. These two geometries interact with each other to modify the response of the whole. This parametric study of the modulus of residual stiffness derives for a range of 10 core materials used in the marine, aerospace, and construction industries, each core bonded to a range of one to seven skin layers. Test results for measured and predicted show consistently good correlation for the current database 2000, and for results measured in 1995, 1997, and 1998. The predicted results are used in the COREDES (Engi, Inc., North Fort Myers, FL) structural beam equations, which calculate the loads, de-flection, stress, and the bilinear elastic curve for structural sandwich panels. The correlation to three-beam test data results is very good overall for one-to three-layer fiberglass skins on a standard thickness core, and these results clearly show has no effect on predictive results above five skin layers. The excellent correlation of these plotted comparisons of predictive data to test data indicates that this modulus is an important governing factor in the response of sandwich beams.
Preface to Recent Studies Involving the RMS Titanic
Authors: Garzke William H.
Published: January 2021

The loss of the RMS Titanic has fascinated the public for nearly a century. When Dr. Robert Ballard discovered the wreck in September 1985, it was determined that the ship had sustained a hull failure and another visit in 1986 found that a portion of the midsection of the ship was missing. Recent use of deep diving Remotely Operated Vehicles (ROV) and modern computer techniques have enabled evidence that has been recovered or seen on the seabed to be analyzed to determine what really caused this magnificent ship to sink and break apart. Yes, the ship did collide with an iceberg, but were there other contributing factors?
Metallurgical Analysis of Wrought Iron From the RMS Titanic
Authors: Hooper Jennifer J. , Foecke Tim , Graham Lori , Weihs Timothy P.
Published: January 2021

The discovery of the RMS Titanic has led to a number of scientific studies, one of which addresses the role that structural materials played in the sinking of the ship. Early studies focused on the quality of the hull steel as a contributing factor in the ship's rapid sinking, but experimental results showed that the material was "state-of-the-art" for 1911. Instead, it was suggested that the quality of the wrought iron rivets may have been an important factor in the opening of the steel plates during flooding. Here the quality of RMS Titanic wrought iron is examined and compared with contemporary wrought iron obtained from additional late 19th-/early 20th-century buildings, bridges, and ships. Traditional metallurgical analysis as well as compositional analysis, mechanical testing, and computer modeling are used to understand the variation in the mechanical properties of wrought iron as a function of its microstructure.
Riveted Hull Joint Design in RMS Titanic and Other Pre—World War I Ships
Authors: Woytowich Richard
Published: January 2021

Beginning with an overview of riveted joint construction, this paper shows that the efficiency of riveted joints in pre-World War I ships decreased as plate thickness increased. In the case of the RMS Titanic, some of the joints involved in the iceberg impact were only about 27% as strong as the plates they connected. A finite element model is used to show how such a joint would respond to the sort of out-of-plane load that the iceberg would have applied. For one possible load configuration, the joint failure is recreated. Finally, although Titanic and her sisters were not built to class, the design of the riveted joints is examined in the context of relevant Lloyd's Register of Shipping Rules.
An Object-Oriented Model for Conceptual Ship Design Supporting Case-Based Design
Authors: Delatte Ben , Butler Alley
Published: January 2021

Design of ships, including warships such as submarines, is normally begun with a feasibility study. The feasibility study provides initial proof of concept and becomes a basis for further efforts. Because time and information for analysis is usually limited, historical design data is typically used to help with the generation of conceptual designs. To support automation of design efforts under these circumstances, adaptation and reuse of earlier designs represents a very useful paradigm. This paper presents a data storage system to store historical design data for subsequent reuse in conceptual design. The database is designed to support case-based reasoning and other similar processes in which recall of past solutions becomes a basis for adaptation to form a new solution. The stored data support conceptual design for a submarine or ship using previous design information. The data involve complex geometric information, and an object oriented database system is presented. The object-oriented database stores complex information in a useful format for recall on a "similar to" basis. This architecture allows case-based reasoning and other recall-based systems to utilize feature-based design information based on similarity to new requirements. To avoid using information that is sensitive and/or classified, this system is demonstrated using unclassified commercial submarine and Maritime Administration ship data. Experiences with two generations of prototype software are discussed, and conclusions about system utility are reached.
A New-Generation Motion-Control System for Twin-Hull Vessels Using a Neural Optimal Controller
Authors: Kenevissi Farhad , Atlar Mehmet , Mesbahi Ehsan
Published: January 2021

A new ride control system using a neural optimal controller (NOC) is developed and applied to improve the heave and pitch motion responses of two twin-hull vessels operating in regular head seas. A time domain model for the vessel dynamics in the presence of active fin control is used to simulate the vessel and fin motion responses. An online switching procedure is introduced to select among a number of linear quadratic regulator optimal controllers, designed for different operating conditions of the vessel, to improve the system robustness. Although the online switching offered better robustness and performance characteristics, in between switching operating points, it still remained suboptimal. Therefore, an artificial neural network (ANN) controller was developed as an alternative and initially trained to emulate the same level of control at a number of design operating points, as a NOC. The advantage of this novel application is that practical difficulties in applying an online switching procedure are no longer present and, more importantly, the ANN has been capable of nonlinear generalization to give a near optimal solution away from the trained operating conditions.
Multiobjective Design Optimization of B-Screw Series Propellers Using Evolutionary Algorithms
Authors: Benini Ernesto
Published: January 2021

Methodical series are still widely used in the preliminary design of light-and moderate-duty marine propellers. If the above series enables standard screws to be designed by simple chart methods, they do not help the designer to deal with a complex design involving multiple and conflicting objectives. In this paper, a multiobjective optimization method of B-screw series propeller is introduced that makes use of an evolutionary algorithm maximizing both efficiency and thrust coefficient with a constraint determined by cavitation. The capabilities of the method are illustrated and discussed in detail. The results following the application of the method are given in the form of diagrams, which can be implemented on a common personal computer and used to derive optimal screw configurations in real time.
Real-Time Simulation of Ship Impact for Crew Training
Authors: Simonsen Bo Cerup
Published: January 2021

Real-time simulation of marine accidents and representation in a realistic, virtual environment may be an efficient way to train emergency procedures for ship's crews and thus improve safety at sea. However, although various fast, simplified methods have been presented over the past decades, the real-time simulation of ship grounding and collision events poses a number of challenges. This paper presents a set of theoretical models and methods by which it is relatively easy to implement collision and grounding modeling capabilities in existing, real-time marine simulators. Most notably, the paper contains methods for fast prediction of collision and grounding motion and a method that transforms any motion into a set of forces. The latter method allows that the grounding and collision impact modules interact with the simulation software only through specification of external forces on the hull. The efficiency of the developed procedures is demonstrated by three examples: ship berthing (impact with quay), ship grounding on a pinnacle rock, and ship-to-ship collision. Although the paper specifically addresses ship impact problems, it is believed that a part of the presented methods would be advantageous to use in other types of time simulation where it is desirable to switch between direct time integration and some other known, stabilized solution, without a major redesign of the program architecture.
Time-Based Survival Criteria for Passenger RO/RO Vessels
Authors: Jasionowski Andrzej , Vassalos Dracos , Guarin Luis
Published: January 2021

This paper outlines the study undertaken within the framework of research aiming to address the compound problem of the absolute time available for passenger evacuation on a damaged passenger/RO/RO vessel undergoing large-scale flooding of car deck spaces. Deriving from extensive experimental information and utilizing static equivalent method (SEM) principles, a methodology for predicting ship survival time is proposed that accounts for wave characteristics, water ingress/egress, and vessel survivability. The progress achieved to date is discussed, and aspects needing further investigation are highlighted.
A Performance-Based Assessment of the Survival of Damaged Ships: Final Outcome of the EU Research Project HARDER
Authors: Tagg Robert , Tuzcu Cantekin
Published: January 2021

The paper presents the results of the EU Research Project HARDER with regard to the development of generalized formulations to predict the probability of survival of a damaged ship in a seaway. The methodology follows the procedures used to develop the survivability functions for the probabilistic damage stability regulations for passenger ships developed in the 1960s but makes use of an extensive series of a new model test carried out both as part of the HARDER Project and as part of independent external model tests. Simplified formulations based on static calculations have been proposed and correlated to the model test results. Two formulations are proposed, one to be applied to all types of ships, and an additional function based on the static equivalent method (SEM) methodology, which is suitable for roll-on/roll-off (RO/RO) ships (or any other ships with large unsubdivided horizontal spaces near the final damaged waterline). These formulas are currently under consideration by the International Maritime Organization (IMO) for the new harmonized damaged stability regulations in the upcoming SOLAS 2006 revisions.
Discussion of Paper 1: Resistance and Propulsion Characteristics of the VWS Hard Chine Catamaran Hull Series '89
Authors: Müller-Graf Burkhard , Radojcic Dejan , Simic Aleksandar , Savitsky Daniel , Hackett John P. , Fung Siu C.
Published: January 2021

The authors wish to thank the discussers for their comments and questions. Some questions were raised because we could not include all specific details and explanations concerning the layout of the Series '89 due to space limitations. We are grateful to Dr. Savitsky for his friendly introduction to our subject.
Some Remarks on Theoretical Modeling of Damaged Stability
Authors: Umeda Naoya , Kamo Tomoko , Ikeda Yoshiho
Published: January 2021

The authors raise several points for discussion to develop theoretical modeling of damaged stability in waves. First, hydrodynamic modeling of behaviors of a damaged ship in waves is discussed in the light of multiple time scale expansion. This provides a theoretical background to calculate hydrodynamic forces acting on a hull with sinkage and heel due to water accumulation inside the hull taken into account. Second, the reason why the International Towing Tank Conference (ITTC) benchmarktesting for a damaged ship resulted in insufficient prediction of roll motions is discussed based on results of model experiments with a flooded compartment model. Third, survivability of a damaged ship with multiple decks in a damaged compartment is discussed in the light of model experiments on flooding of a pure car carrier (PCC) in calm water and waves. The experimental study shows that survivability of such a ship is different from that obtained in a static assumption even in calm water, and its dynamic behaviors in waves significantly depend on initial state and transient process of flooding. If so, the model test method used in the Stockholm Agreement can be inappropriate for this type of ship.
A Study on the Influence of Ship Roll Characteristics on the Risk of Cargo Shifting
Authors: Ryrfeldt Anna
Published: January 2021

In a previous work a methodology for assessing the risk of cargo shifting has been developed and used to study the influence of different parameters on the risk of cargo shifting. It has been found that ship rolling is one of the major contributing factors of cargo shifting. Linear theory of ship motions is presently used in the methodology because of computational efficiency and simplicity. Because the roll motion is complex and difficult to predict because of nonlinearities, the present study has been performed in order to study the influence of the roll motion on the risk of cargo shifting. This study may be seen as a sensitivity analysis of roll motion with respect to cargo shifting. The risk has been studied by the number of potentially dangerous conditions and how they depend on such parameters as wave height and period, and ship heading toward waves. The influence of roll amplitude and phase, as well as the influence of roll stabilizing devices, on the number of dangerous conditions is studied for two vessels and two load cases each. Roll amplitude influence is analyzed by changing the amplitude of the transfer function, and the results show that the influence of roll amplitude is very large. This influence is especially marked when the roll amplitude is large and the vertical and horizontal accelerations are small to moderate. The influence of roll stabilizing devices is studied by cutting of the resonance peak in the transfer functions. The results show that roll stabilizing is often efficient but that it can be more important to choose load case in order to attain good seakeeping characteristics, especially with respect to roll motion.
A Study of Hydrodynamic Characteristics of Boundary Layer With Algae Roughness
Authors: Subramanian Chelakara S. , Shinjo Nagahiko , Gangadharan Sathya N.
Published: January 2021

Filamentous algae fouling, such as Enteromorpha clathrata, is a soft and hairylike roughness that sometimes grows even thicker than a normal boundary layer. Typically, such fouling has been treated as traditional roughness functions to yield hydrodynamic characteristics. This technique has been successfully used for a thin fouling layer. However, it may not be applicable on a thicker layer, as the present study found substantial fluid flow within the layer. For such cases, the roughness cannot be treated simply as a passive geometric variable, but its kinematics and interactions with the flow must be considered. The inner law (log law) dynamics may be abnormal to yield any meaningful roughness function if it is calculated in the traditional way as the departure of a rough-wall log law profile over a smooth-wall log law profile. In the present research, velocity measurement of the E. clathrata roughness boundary layer using pitot-static tube and laser Doppler velocimeter (LDV) were compared. Large discrepancies in the velocity profiles within and in the vicinity of the roughness layer were observed between the two methods. The pitot-static tube data showed significantly high velocities (60% to 80% of the free stream) in the inner layer as compared to a smooth wall boundary layer. This local increase in velocity is believed to be the result of elastic transfer of free-stream energy to the near-wall motions by the E. clathrata filaments. Consequently, the usual assumption of the normal pressure gradient as a negligible second-order term for a normal zero-pressure gradient boundary layer may not be valid for the present kind of roughness. The LDV velocity measurements near and within the roughness layer have large uncertainties due to interference of the probe volume by the E. clathrata filaments. Above the roughness, the pitot-static tube and LDV profiles show relatively good agreement. It is concluded that for accurate prediction of the wall shear stress with E. clathrata-type of bio-fouling roughness, the Clauser velocity loss function should include a form drag factor instead of only the viscous drag factor.
Large Passenger Ship Safety: Time-to-Flood Simulations
Authors: van ‘t Veer Riaan , de Kat Jan , Cojeen Paul
Published: January 2021

This paper presents the first results of a study on the behavior of a damaged large passenger ship in waves. It shows how numerical tools can be applied to derive trends in relation to the time to flood for this type of vessel. Relevant capsize criteria have been applied to long duration motion time series, from which the time to flood was established as a function of sea state. The results suggest that the large passenger ship considered is safe according to the criteria for waves up to 4.5 m significant wave height. In more severe waves the time to flood decreases rapidly from 10 hours to below 1 hour (in sea states of 6.5 m significant wave height and higher). The criteria used for assessing safety are of major importance for determination of the time to flood.
Ultimate Strength of Aluminum Plates and Stiffened Panels for Marine Applications
Authors: Paik Jeom Kee , Duran Alexandre
Published: January 2021

The use of high-strength aluminum alloys in marine construction has certainly obtained many benefits, particularly for building fast ferries and also for military purposes. It is commonly accepted that the collapse characteristics of aluminum structures are similar to those of steel structures until and after the ultimate strength is reached, regardless of the differences between them in terms of material properties. However, it is also recognized that the ultimate strength design formulas available for steel panels cannot be directly applied to aluminum panels even though the corresponding material properties are properly accounted for. This is partly due to the fact that the stress versus strain relationship of aluminum alloys is different from that of structural steel. That is, the elastic-plastic regime of material after the proportional limit and the strain hardening plays a significant role in the collapse behavior of aluminum structures, in contrast to steel structures where the elastic perfectly plastic material model is well adopted. Also, the softening in the heat-affected zone significantly affects the ultimate strength behavior of aluminum structures, whereas it can normally be neglected in steel structures. In this paper, the ultimate strength characteristics of aluminum plates and stiffened panels under axial compressive loads are investigated through ANSYS elastic-plastic large deflection finite element analyses with varying geometric panel properties. An "average" level of welding-induced softening and initial imperfections is assumed for the analyses. Closed-form ultimate compressive strength formulas for aluminum plates and stiffened panels are derived by regression analysis of the computed results.
An Investigation into the Loss of the Steel Bark Admiral Karpfanger ex L'Avenir
Authors: Ghys Roger , Cormack Neil W.
Published: January 2021

As the era of the deep-water commercial sailing ships was coming to its close, several steamship companies with concern for their deck officer requirements decided to train their future officers as cadets in training ships under their own house flags. These were in the form of square-rigged vessels fitted to accommodate several cadets. They were classified as cargo-cum-cadet ships, and for the purpose existing ships were purchased. The cadets were given instruction in seamanship, navigation, cargo stowage, sailmaking, boatwork, and ship's business, all with the object that on graduation and so qualified they would be posted to company steamships as deck officers.
Hull Form Optimization for Hydrodynamic Performance
Authors: Grigoropoulos Gregory J.
Published: January 2021

A method for optimizing hull forms with respect to their hydrodynamic performance in calm and rough water is presented. The method is based on an initial optimization of a parent hull form for seakeeping and the improvement of the resulting optimum hull form for calm water resistance. In the first part of the method, variant hull forms differing from a parent in the main dimensions and/or in one or more hull form parameters, such as CWP, LCF, CB, LCB, KB, CP, are automatically generated and their seakeeping qualities evaluated. When appropriate ranges for the principal characteristics and parameters of the hull form under investigation are prescribed, a formal optimization procedure is used to obtain the variant with the best seakeeping behavior. The weighted sum of the resonant values of selected ship responses for a number of ship speeds and headings in regular waves forms the objective function. The Hooke and Jeeves algorithm is used to accomplish the optimization. The procedure results in a set of trends regarding the proposed variations of the selected hull form parameters, within the specified constraints. These trends are then applied on the parent hull to derive an optimized hull form with fair lines. Subsequently, this hull form can be locally modified to improve its calm water resistance or, as it should be done, its propulsion characteristics. The applicability of the method is demonstrated in two cases: a conventional reefer ship and a naval destroyer. Scaled models of the parent and the optimized hull forms have been tested for calm water resistance and seakeeping. In both cases the validity of the methodology is demonstrated.
Experimental Study on the Influence of Appendages on a Yacht Rolling at Zero Froude Number
Authors: Klaka Kim , Renilson Martin
Published: January 2021

Yachts tend to roll uncomfortably while at anchor, causing discomfort to the crew and passengers, generating additional stresses on equipment, and making such operations as embarking and disembarking hazardous activities. Currently, there is a dearth of data regarding roll motions at zero forward speed for hull shapes dominated by large appendages. Hence, an experimental study into the effect of large appendages on roll motion was undertaken. The model test results are presented, showing how changes in appendage geometry alter the roll response.
Critical Needs for Ship Maneuverability: Lessons From the Houston Ship Channel Full-Scale Maneuvering Trials
Authors: Landsburg Alexander C. , Barr Roderick A. , Daggett Larry , Hwang Wei-Yuan , Jakobsen Bent , Morris Mike , Vest Lou
Published: January 2021

"I think the architects and engineers that design ships for the sea, where they spend 99% of their time, forget that at some point they still have to get up the ditches to load or discharge their cargo. Someday when a high-profile accident does occur, ship builders might even be brought into the civil arena and found criminally negligent and liable for building underpowered and poor handling ships."A pilot's view The Standards for Ship Maneuverability approved by the International Maritime Organization (IMO) in 2002 represent a significant step forward in ensuring adequate maneuverability of ships. The Standards provide numerical criteria for assessing the adequacy of maneuverability in deep, unrestricted water at sea speed. Explanatory notes to the Standards provide useful guidelines to the assessment and validation process that help with various issues, such as adjusting full-scale trial results for environmental and loading conditions. Major issues exist, however. In question is the ability of the standards to ensure adequate maneuverability in shallow, restricted, and congested waterways under vessel meeting and passing conditions with the interaction effects, bank suction, and other situations that are encountered in normal port, harbor, and waterway operations. Historically, even in shallow water that is unrestricted, only a couple of ship trials have ever been conducted due to the great cost to prepare for such tests. The lack of accurate full-scale data has seriously limited the accuracy capable of being built into mathematical prediction models. Recently, however, revolutionary positioning technology has enabled collecting highly accurate track and vertical position data on ships operating in shallow and restricted water, with and without interacting ship traffic. Accurate mathematical modeling of ship operations in complex harbors and waterways has become a critical need, and now the possibility of advancing the science finally exists. With accurate full-scale trials data and improved prediction techniques, such as computational fluid dynamics, such ability now seems attainable.
Research Improving the Safety of Offshore Helicopter Operations
Authors: Rowe Stephen J. , Howson David , Sparkes Paul
Published: January 2021

With the development of the Gulf of Mexico's deep-water fields, helicopter transportation is being required to serve larger offshore platforms located at greater distances from the shore. Although the weather climate is relatively benign, the helicopter operations to these new platforms are becoming more akin to North Sea operations. In particular, the requirement to evacuate large and distant platforms in advance of a hurricane may put a particular premium on demonstrating the safety of such operations in worsening weather conditions. The paper outlines progress and gives example results from a number of research themes aimed at improving the safety of helicopter operations on the UK continental shelf. The themes include ways of minimizing the risk posed by the aerodynamic hazards in the vicinity of helidecks on large offshore platforms, improving the emergency flotation systems for helicopters forced to ditch in the sea, and improving the crashworthiness of such systems so that helicopters that crash into the sea are more likely to float following impact. New motion criteria being developed for operations to helidecks on floating vessels and improvements to helideck lighting schemes are also described.
Cost-Benefit Analysis for Ship Automation Retrofit: The Case of Icebreaker Frej
Authors: Lyridis D. V. , Psaraftis H. N. , Ventikos N. , Zacharioudakis P. , Dilzas K.
Published: January 2021

A detailed cost-benefit analysis of a retrofit of the Advanced Technology to Optimise Maritime Operational Safety (ATOMOS) platform on board icebreaker Frej is presented. After accurately determining the relationship between the costs and benefits, an analysis is implemented in order to assess the most basic advantages and disadvantages of the suggested retrofitting action in monetary terms. A two-step approach is adopted. The first step is to define the major categories of the ship operational aggregate costs and benefits (for example, the actual cost of the ATOMOS platform and of equipment not part of the ATOMOS platform but still necessary for its installation and operation, or the expected crew decrease because of the higher degree of automation). The second step is to examine the various basic components of these categories (for example, administration and training cost, required automatic radar plotting aid [ARPA] and electronic chart display and information system [ECDIS] equipment acquisition cost, fuel benefits, and insurance benefits). The cost-benefit analysis performed is followed by a sensitivity analysis of the most important factors affecting the net present value of the investment. It is shown that it takes about 5 years for the ATOMOS retrofit to be fully paid back by the annual savings it offers and it takes about 6.5 years for the net present value of the investment to turn positive. This coupled by the increased vessel safety justifies the decision to retrofit Frej with the ATOMOS platform. Furthermore, it is found that the cost of the ATOMOS platform, the benefits from crew decrease, and the interest rate are those factors that essentially determine the profitability of the investment. In the case of Frej, it is concluded that the retrofit is worth undertaking for the majority of future scenarios.