bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerically Controlled Machining of Propeller Blades
Authors: Nittel Mark F.
Published: January 2021

This paper describes state-of-the-art manufacture of ship propeller blades with numerically controlled(NC) machining. A brief explanation of the rationale for NC machining is provided, followed by a discussion of the operating experience of a blade machining center over the past six years. Some of the unique considerations involved in the NC programming and machining processes are described along with some of the most common production problems. The factors leading to the company's decision to expand the blade machining center are discussed along with a description of the design and procurement of the new equipment and facilities. Tolerances achieved by NC machining and hand finishing are compared.
System Analysis of River-Sea Container Transportation for Overseas Trade in the Yangtze Valley
Authors: Li Zhan , Yang Yu
Published: January 2021

A mathematical model of a river-sea container transportation system is developed. System analysis of a river-sea container transportation system for overseas trade in the middle and lower reaches of the Yangtze River is performed by using the theory and method of 0–1 integer programming. The optimal transportation strategy and fleet configuration are obtained. In addition, the algorithm and software developed by the authors can be used conveniently on a microcomputer.
Chevron's 78000-DWT Lightering Tankers
Authors: Ternus R. A. , Buetzow M. R. , Selle E. D.
Published: January 2021

Chevron operates two refineries on the U.S. Gulf Coast, both of which receive imported crude oil by tanker. Very large crude carriers (VLCC's) load this crude overseas and transport it to international waters in the Gulf of Mexico. Here it is transferred at sea to smaller lightering vessels by ship-to-ship transfer. The lightering vessels must be small enough to satisfy the channel and refinery dock dimensional constraints for draft, beam, and length. In 1988 Chevron took delivery of two new 78000-dwt tankers which replaced older conventional tankers that provided this lightering service in the past. These new ships incorporate many specialized features to increase capacity and reduce the turnaround time in this trade. Maneuverability is enhanced by use of a bow thruster, Schilling rudder, and controllable-pitch propeller. Cargo transfer operations are expedited with high-capacity submerged cargo pumps, a special lightering hose crane, and a highly automated cargo control system. These and other features will permit one of these vessels to deliver crude at a rate more than twice that which could be sustained by a conventional tanker. This paper describes these ships in detail and focuses on the special features that together permit this dramatic improvement in lightering performance.
Design, Manufacture, and Testing of Large Reduction Gears for Diesel Ship Propulsion Systems
Authors: Gold Peter , Watzlawek K. Heinz , Karaszewski Zbigniew J.
Published: January 2021

The dramatic increase in both the size of ships and the power of propulsion systems over the past 15 years has led to a desire for shorter machinery spaces and lighter equipment in order to provide additional cargo carrying capacity. Many equipments and reduction gears in particular have experienced a growing number of problems due to compact designs with reduced scantlings. Consequently, high-horsepower and low-rpm gear units were developed that resulted in incompatibility of machinery and ship. Those marginal designs combined with manufacturing inaccuracies were in most cases the result of overzealous cost reduction programs. This paper presents some of the elements of a state-of-the-art reduction gear evolution cycle that will result in successful gear operation and continued long life.
A Toroidal Hydrodynamic Absorber for Damping Low Frequency Motions of Fixed and Floating Offshore Platforms
Authors: Venugopal Madan
Published: January 2021

An application of a toroidal hydrodynamic absorber is suggested for reducing low-frequency bending vibrations of fixed offshore platforms and planar oscillations of tethered platforms. A design methodology for such an absorber is presented. Results of an experiment intended to illustrate the effect of the absorber are presented.
Effect of Openings in Ring-Reinforced Shells
Authors: Deans Douglas
Published: January 2021

The ring-reinforced shell is a primary structure used in the marine and industrial world. Stress and buckling analysis of such structures is generally based on axisymmetric analysis wherein all openings in the shell are neglected. In real life, such structures have a large number of openings often made in a random manner. In order to design an appropriate reinforcement at such an opening, it is necessary to carry out a detailed local stress analysis. Such an analysis can be made either through the use of part models or by superelements which include the entire structure, as well as the local reinforcement. Zoom analysis using the whole model is expensive and requires knowledge of multilevel super element techniques. Analysis using part models is cheaper and can be equally reliable. This paper investigates the effects of openings on the stress distribution in ring-reinforced shells, such as submarines, using a finite element model. The stress concentration factors (SCF's) in areas adjacent to the opening are determined from this analysis. Using these SCF's, modeling rules for utilization of part models are developed and recommended for use.
The New International Standard for Subdivision and Damage Stability of Dry Cargo Ships
Authors: Gilbert Randall R. , Card James C.
Published: January 2021

The U.S. Coast Guard does not have subdivision or damage stability requirements for dry cargo ships, although for many years the U.S. Maritime Administration (previously the Maritime Commission) has required cargo ships built under their subsidy and loan guarantee programs to meet a one-compartment standard of subdivision. The 1960 International Convention for the Safety of Life at Sea (SOLAS) recommended studies be initiated on the extent to which it would be necessary and practicable to apply subdivision and damage stability requirements, having as its aim the formulation of international standards. After nearly 27 years, in September 1987 the International Maritime Organization (IMO) SubCommittee on Stability and Load Lines and on Fishing Vessels Safety agreed on a set of draft regulations. The IMO Maritime Safety Committee (MSC) in April 1988 approved the draft regulations and published them as MSC/Circ.484. The MSC in April 1989 set the Required Subdivision Index, and finalized the regulations. They are scheduled to be adopted into the 1974 SOLAS Convention in May 1990, and will then come into force in February 1992. On April 6, 1988, an Advance Notice of Proposed Rulemaking, based on the IMO draft regulations, was published in the Federal Register. This initiated Coast Guard action to require dry cargo ships, both U.S. and foreign, to meet the new subdivision and damage stability standard. This paper recounts the problems leading up to the establishment of the new international standard, explains the various factors involved in the formulation of the probabilistic method of measuring subdivision, and explains how to apply them to the design of ships.
The Promise of Advanced Naval Vehicles for NATO
Authors: Lavis David R. , Rogalski William W. , Spaulding Kenneth B.
Published: January 2021

Advanced naval vehicles (ANVs), defined here as surface effect ships (SES), hydrofoils, and small-waterplane-area twin-hull ships (SWATHs), hold significant promise for a number of naval missions, offering advantages in many operational areas. These advantages can extend to life-cycle costs when total force requirements are considered. NATO Special Working Group 6 (SWG/6), of which the United States is a member, has been particularly active in the evaluation of ANVs for various missions. A number of the participating nations have ongoing ANV development programs or have developed point designs for evaluation by SWG/6. This paper describes the SWG/6 organization and provides an introduction to some of these ANV programs. It presents the highlights of a series of antisubmarine warfare (ASW) corvette point designs developed as part of one of the SWG/6 initiatives and describes aspects of their assessment against conventional hull forms. The paper concludes with a description of some new SWG/6 programs.
SWATH Structure: Navy Research and Development Applications
Authors: Sikora Jerome P. , Dinsenbacher Alfred L.
Published: January 2021

The potential for enhanced seakeeping and increased operational effectiveness for certain missions has generated an interest by the U.S. Navy in small-waterplane-area twin-hull (SWATH) ships. Because of the novelty of these vessels, traditional design approaches cannot be used. Hence, the David Taylor Research Center has invested a considerable effort to develop suitable criteria for primary Ioadings, secondary Ioadings, and the structural response of these ships. This paper presents an approach for determining the maximum seaway Ioadings on SWATH ships and summarizes the results in simple design algorithms. Secondary slam Ioadings from model tests are presented. Algorithms for predicting the stress distributions on primary structure are also presented. Finally, some lightweight alternatives to conventional steel grillage secondary structure are presented. Overall, structural weight reductions are possible, with the biggest potential benefits arising from structural designs which resist secondary loads.
Expert System Applications to Ocean Shipping—A Status Report
Authors: Dumbleton John J.
Published: January 2021

Artificial intelligence has been emerging as one of the fastest growing technologies during the past five years. One subset of this discipline that has experienced phenomenal growth, when measured by spending levels by the commercial sector and all levels of government, is that of Expert Systems. The development of Expert Systems applications for shipping operations has also been growing, albeit at a somewhat slower rate. However, a number of very innovative systems are nearing completion in the United States, as well as in Europe and Asia, that will radically change how vessels are operated and managed. This paper provides an overview of Expert Systems concepts, a discussion of the Maritime Administration's program of research and implementation of this technology, and a review of systems and other projects that are nearing completion in the United States as well as abroad. The paper concludes with prospects for future development of Expert Systems as the merchant fleets of the world look for ways to improve their competitiveness.
Design of a 40-Ft Multihull Sailboat for Offshore Racing
Authors: Antrim James K.
Published: January 2021

An overview of modern multihull sailboat design is presented, with an emphasis on the factors contributing to speed. In particular, the design of a 40-ft trimaran is reviewed. Evolution of the rig and shape and configuration of hulls and underwater foils are examined. Thinking behind deck and interior layout is discussed. The principal goal of this design was a multihull for offshore racing, normally with a one or two-man crew, and with a victory in the Double Handed Round Australia Race as the initial target. Secondarily, the boat was to fit the Formula 40 rule, possibly loosely, in the hopes of getting some Formula 40 racing started on the U.S. West Coast.
Air Cushion Vehicles and Surface Effect Ships for Great Lakes and Great Rivers Transportation
Authors: Allison John L.
Published: January 2021

A brief introduction to air cushion vehicle (ACV) and surface effect ship (SES) technology is presented, with past and present examples, to show that this technology may now be considered mature. Applicability of ACVs and SESs to transportation on the Great Lakes and rivers of Canada and the U.S. is discussed, with some emphasis on year-round service in the regions affected by ice. An indication of present design capabilities is provided with some examples of application to typical sets of requirements. Future developments are outlined in the light of the rapid expansion of air-supported ferry operation in other parts of the world, and military and Coast Guard applications in the U.S. and Canada. Some data on acquisition and operating costs are presented in comparison with those for other hull forms, with information on the type of technical and port support required for ACV and SES operation. Numerous references are provided to enable the reader to pursue the topics discussed in greater detail than is possible in a short paper.
The Refurbishment of Rotating Steam Turbine Blades
Authors: Hendelman J. C. , Bazzini R. J.
Published: January 2021

The remanufacture and repair of steam turbine parts continues to be a cost-effective and viable alternative to replacement with new parts in many cases, providing improved scheduling flexibility in situations where replacement part deliveries cannot support maintenance schedules, and where the cost of replacement parts is not justified when alternatives exist. The extension of these repair techniques to rotating steam turbine blades was a logical extension of the technology available to turbine owners and operators. With turbine blade failures remaining the leading cause of turbine failures in the United States, and 75 percent of all blade failures occurring in the L-0 and L-1 stages, many blades not previously considered candidates for repair are being reevaluated for refurbishment. Although the power generating utilities have led the way in turbine part "salvage" via repairs, the application of the techniques described herein are fully applicable to marine steam propulsion units. These being variable-speed machines, operation off "design point" is more common and blade service is more severe in most cases.
Fiber Optics for Shipboard Sensing and Information Transfer
Authors: Zugger M. E. , Hoffman R. E.
Published: January 2021

Fiber optics has been a rapidly growing field over the past decade. It has been utilized extensively by the telecommunications industry, an application which requires the transmission of large amounts of information at a high data rate. More recently, many firms have initiated development of fiber optic sensors. These are transducers that use purely fiber optic technology for sensing physical parameters, such as pressure, temperature, and strain. Trends and projections for ships of the future indicate that dramatically increased monitoring and computer control will be necessary for most ship systems. Not only will automation be used for meeting reduced manning requirements, other economic constraints will require extensive machinery monitoring for improved maintenance scheduling. Integrated navigation systems on commercial ships will require high-resolution displays, and rapid data transfer between satellite, radar, and bottom-sounding sonar navigation subsystems. These applications will require fiber optics both in data transfer networks and in sensors. This paper is intended to apprise the marine engineering community of the potential benefits which fiber optic networks and sensors bring to shipboard installations. A brief tutorial on fiber optics is given, including a discussion of space, weight, and data rate advantages; the various fundamental sensing techniques are explained, and examples of prototype and commercially available sensors for potential shipboard use are provided. The report concludes with an example of a commercial ship application, and an assessment of the action needed by the ship design community and sensor vendors to reap the performance, safety, and economic benefits of this technology.
Pressure Loading of Aluminum Plating
Authors: Brown K. C. , Joubert P. N.
Published: January 2021

The pressure loads applied to yacht hull plating by slamming have been estimated by pressure testing small sections of aluminium hull and comparing the resultant damage with service damage to hulls of similar construction. The structural response of the plating to the pressure load is discussed with reference to current design practice. The design pressures in current use are found to be unrealistically low and the cause of failure has been found to be elastoplastic buckling, rather than bending.
U.S. Commercial Shipbuilding in the 1990s: The Global Context
Authors: Carson Jay P. , Lamb Barbara
Published: January 2021

Since 1982, only five orders for commercial oceangoing ships—all for Jones Act trades—have been placed with U.S. shipyards, largely because the U.S. yards have not been price competitive with foreign shipyards. However, broad economic developments have taken place worldwide during the late 1980s. Given the current and likely situation into the 1990s, will it be possible to build ships competitively in the United States? This paper provides a market-based framework for analysis of these developments and discusses how the U.S. competitive position has improved. Based on market analysis, near-term opportunities for construction of replacements for the aging domestic fleet may be a stepping stone to long-term opportunities for construction of ships in international trades. Suggestions for actions by U.S. shipbuilders, shipowners, and Government are provided.
Producibility Benefits of the Swath Configuration
Authors: De Vries Richard L.
Published: January 2021

Producibility is the term used in shipyards to describe the relative efficiency of constructing one design over another. The producibility of a ship is primarily a function of the ship's configuration. The "box-like" structure of the small waterplane area, twin hull (SWATH) enhances the design flexibility in both the spatial arrangement of the compartments and the outfit arrangement within each compartment. One of the major benefits of the SWATH design is the expected dramatic increase in the number and size of distributive system outfit packages. The location of the major equipment (such as the gas turbine, main propulsion generators and the diesel ship service generators) high and in the center of the upper structure on the SWATH increases the time available to assemble complete outfit packages. The SWATH structural configuration has few complex shapes or intersections, as the majority of the structure is rectilinear and the underwater hulls are composed of simple cones and cylinders. Further, the homogeneity of the SWATH structure results in repeating design details generally throughout the length of the ship with port and starboard mirror image structure. Thus, it is possible to achieve significant cost savings in every area of design and construction. Properly designed, the SWATH configuration can be the most cost-effective platform available for today's low to medium payload ships.
Design Practice for Mooring of Floating Production Systems
Authors: Kwan C. T.
Published: January 2021

A draft "API Recommended Practice for Design, Analysis, and Maintenance of Mooring for Floating Production Systems" was developed recently by the API Task Group on Mooring Design for Floating Structures. This document is closely related to API RP-2P, "Recommended Practice for the Analysis of Spread Mooring Systems for Floating Drilling Units." because both documents address mooring of floating units. However, this document is also different in many ways from API RP-2P because there are significant differences between a floating drilling mooring system and a floating production mooring system. Major differences of this document from API RP-2P are:The design environment is significantly more severe.Dynamic instead of quasistatic mooring analysis is recommended; tension limits are relaxed.Guidelines for thruster-assisted mooring are included.Fatigue analysis is required.

In the course of developing the Draft RP, the API Task Group has done some fundamental work to establish a rational design practice for FPS mooring systems. This paper highlights the new design practice, presents its basis, and points out areas where future work is needed.
The Transverse Plane Motions of Ships
Authors: Hutchison Bruce L.
Published: January 2021

A detailed exposition of the kinematics of the transverse plane motions of ships is provided, with particular attention to the important process of total transverse acceleration in vessel coordinates. The loci of sway, sway velocity and sway acceleration are shown to follow hyperbolic distributions with respect to elevation in both regular and irregular waves. In regular waves the transverse acceleration in earth-fixed and vessel-fixed coordinates are shown to be congruent with a vertical shift in elevation of g/ω2 = λ/(2π). Expressions are given for the elevations minimizing transverse plane processes in regular and irregular waves. In long waves the elevation minimizing total transverse acceleration in vessel coordinates is shown to be g/ωn2 = g[Tn/ /(2π)]2 below the waterline. This is the roll center, which should be used in the traditional analysis of foundation loads. Its location, far below the keel for most vessels, is surprising. The elevation (OP) of the roll axis, which must be used when solving the one-degree-of-freedom equation for roll, is given and is shown to require hydrodynamic coefficients for sway as well as roll. In general, OP does not correspond to an elevation that minimizes any of the transverse plane processes. The effect of hull form, transverse stability and natural roll period on transverse plane motions are examined in an attempt to resolve the dichotomy of views between those who favor ships with low GMT and long natural roll periods and those who favor high GMT with short natural roll periods. It is demonstrated that large values of the beam-to-draft ratio (6/7) with low natural roll periods are advantageous at modest elevations above the waterline. This explains the favorable offshore experience in vessels meeting this description, such as tugs, supply vessels and fishing vessels. At higher elevations long natural periods are shown to present a clear advantage, which supports the preference for low GMT for large passenger vessels, containerships and ships with deck-loads of logs. The trends identified would seem to support the conjecture that, with regard to natural roll period, there is a "forbidden middle" that should be avoided in design.
Refrigeration Effectiveness Aboard Tuna Seiners
Authors: Cottrell Roy H. , Hoyt Jack W.
Published: January 2021

The refrigeration system in use aboard today's modern tuna seiners was developed in the late 1930's for use aboard bait boats. Since that time, fishing methods have changed, vessel carrying capacities have increased tenfold, catch rates have increased fivefold, and individual fishwell sizes have increased fourfold. As a result, although catch rates have 9one up, the refrigeration effect per ton of tuna per well has actually gone down. Despite these trends, the current refrigeration system works remarkably well. This is due partly to its inherent flexibility and partly to the durability of the tuna with respect to its intended canned market. Nevertheless, because of the increase in well sizes and catch rates, a small percentage of fish is currently being lost due to inadequate refrigeration. This results in an economic loss to the fishing fleet. These losses seem to occur when many fish are caught at a time and loaded into large fishwells. While part of the solution is operational changes, some of which have been recommended elsewhere [1], 3 it has been suggested that increasing the refrigeration effect per well will also help overcome problems observed in the present system. Of the many alternatives which could increase the refrigeration effect per well, this paper discusses the addition of an external heat exchanger, called a chiller, to augment the refrigeration effect per well provided by the existing coil evaporators lining the fishwell bulkheads. Available data on refrigeration effectiveness of modern tuna seiners are analyzed and a computer simulation of the system is presented. Other computer results deal with augmentation of the present system by the addition of additional refrigeration capacity through an external chiller. In addition, a new model for the heat transfer involved in freezing fish such as tuna is presented.
Computer-Aided Alignment of Ship Propulsion Shafts by Strain-Gage Methods
Authors: Rao M. N. Keshava , Dharaneepathy M. V. , Gomathinayagam S. , Ramaraju K. , Chakravorty P. K. , Mishra P. K.
Published: January 2021

A generalized procedure to compute all bearing reactions using finite-element and strain-gage techniques is explained. A computational algorithm for computing optimum bearing offsets both for new design as well as existing ships to get optimum bearing reactions is presented along with a numerical example. Advantages of the strain-gage method over other methods in working out a proper shaft alignment are described. A procedure to estimate the existing reactions in all bearings with the aid of strain gages, even for the case of three inaccessible bearings, is explained. By this feature, the strain-gage method is shown to be complete in itself and need not be supplemented by other conventional methods. An ideal architecture for shaft alignment computer software is explained. A technique for online shaft diagnosis in operational conditions using strain gages and onboard computers is shown.
Fatigue Reliability and Inspection of TLP Tendon System
Authors: Ximenes Maria Celia C.
Published: January 2021

The collapse of a tension leg platform (TLP) tendon system due to progressive fatigue of several joints is investigated. Two solution methods for the system reliability problem are proposed. The first method is based on the failure path approach and the second on the order statistics approach. The effects of redundancy and uncertainties involved in the problem are analyzed. Inspection of selected joints is also included in order to evaluate its impact on system reliability.
The Application of Critical Path Methodology to the Management of Ship Design Programs
Authors: Chappell James P.
Published: January 2021

A case study of Critical Path Management (CPM) and the application of this concept to the management of ship design programs are presented. The evolution of modular ship construction and its attendant influence on design products have created a need for an integrated management approach. CPM is presented as the preferred method of managing the effective integration of ship design with ship construction. Although CPM was established in the 1940's, it was not a practical alternative for managing complex, large-scale projects until mainframe computers became widely available to American business. The CPM process is essentially one of developing a computer model of the management plan required to meet the primary goals of the ship design program. By modeling a management plan that includes the key elements of both design development and ship construction in an integrated computer environment, accurate schedules and resource requirements are produced. More importantly, if the performance to these schedules deviates, either positively or negatively, the net impact to the program is immediately known.
Design and Trials of a New River Towboat Propeller
Authors: Christopoulos B. , Latorre R.
Published: January 2021

Improvement in river transport requires adopting more efficient towboat propellers. This paper summarizes the design and towboat trials of a new semi-Kaplan propeller with an unconventional pitch distribution. A comparison of towboat trip records shows that operation with semi-Kaplan propellers resulted in improvements over operations with conventionally designed propellers. These improvements included a 13.5 percent increase in barge mpg of fuel and a 10 percent increase in tow speed. The trials with the semi-Kaplan propeller indicated only a small increase in towboat vibration levels. The adoption of this new propeller has potential for improving present river transport.
Occupational Hygiene in the Merchant Marine with Special Reference to Arctic Operations
Authors: Dean John , Yoshida Ken
Published: January 2021

The problem areas of occupational hygiene in merchant marine operations, with a special reference to arctic operations, are discussed. Relevant chemical, physical, biological, and ergonomic environmental stresses of concern are outlined. It is found that the severity of arctic conditions makes the task of occupational hygienists critical to the performance of marine workers, A brief history of occupational hygiene is also given.
Marine Diesel Propulsion Plants for the U.S. Navy: Requirements for Geared Medium-Speed Engines
Authors: Karaszewski Zbigniew J. , Schaefer Wilhelm F.
Published: January 2021

Economic considerations for reduced operational costs of U.S. Navy diesel ships and the experience of European operators with diesel propulsion can no longer be ignored. The operational characteristics of high-powered diesel engines, compared with those of the steam or gas turbines, as prime movers, is different with respect to the propulsion system balance of torque variations. Maintenance is also quite different when compared to that of turbine installations. From an engineering point of view it is essential to have well-defined criteria for achieving balanced main components and system design. The sudden turn of American operators—with predominant knowledge and confidence in steam or gas turbine propulsion design and operation—towards marine diesel plants could result in unacceptable operational scenarios of existing diesel ships and eventual abundance or long delay of diesel power plant applications in the United States. This paper provides a broader understanding and greater appreciation of the technical aspects governing the application, design and operation of a state-of-the-art diesel propulsion plant.
Responsibilities Pertaining to Drawing Approvals During Ship Construction and Modification
Authors: Fisher Kenneth W.
Published: January 2021

This paper discusses the obligations and responsibilities of the shipowner and the shipyard pertaining to the approval of drawings during ship construction or modification, and the resolution of disputes that frequently arise as the result of misinterpretation of or ambiguity in contract language. The reasons for transmittal of drawings between the builder and contractor (shipowner) are reviewed, and sample statements from standard contracts in the United States, Europe, and Japan are compared. The author fashions a typical conflict between principals which exposes the confusion produced by ambiguous definitions in contract language.
Two-Dimensional Hydroelastic Analysis of Very Large Floating Structures
Authors: Che Xiling , Wang Dayun , Wang Minglun , Xu Yingfan
Published: January 2021

We have reached a stage at which we are capable of building very large floating structures to meet the steadily increasing needs of ocean resource utilization or to fulfill some special industrial or civil purpose. When such a structure is large enough, its behavior in waves may be substantially different from that of ordinary offshore structures due to low resonant frequencies of the deformable body, and its analysis may require different techniques. In this paper, a two-dimensional hydroelastic theory is applied to a very large floating structure that may be multimodule and extend in the longitudinal direction. A revised strip theory is employed to analyze the hydrodynamic coefficients, but some modifications are introduced to allow for multibody cross sections. The structure is considered to be a flexible beam responding to waves in the vertical direction. Numerical examples are presented with reference to an integrated system of semisubmersibles. A simple model for engineering estimation is also presented.
A Review of Offshore Supply/Work Vessels for Application to USCG Aids to Navigation Missions
Authors: Young Ryan R.
Published: January 2021

The development of offshore supply vessels (OSV's) is examined as an instructive example of the influences of regulations, technology and market forces on ship design. The adaptation of OSV's for the Coast Guard's buoy tending mission is examined. Newly compiled data on foreign OSV parameters for design purposes and a critical bibliography of references on OSV's are included as appendices.
A History of America's Cup Yacht Racing
Authors: Herreshoff Halsey C.
Published: January 2021

The 140-year history of the America's Cup, the oldest and most distinguished prize in world sport, is summarized from the author's vantage point of belonging to a family of boat designers and builders who contributed to the total dominance of American yachts from the beginning into the 1980s. Particulars and performance of the most important designs are illustrated. The sensational quarrel in the 1980s over how the design rules should be interpreted, culminating in the bizarre race of 1988, is described. The new International America's Cup Class is evaluated for the 1992 event in San Diego and future races.
Organization Theory and Shipbuilding: A Brief Overview
Authors: Lamb Thomas
Published: January 2021

The paper presents the author's viewpoint of the subject rather than the results of an extensive group survey or study. The paper reports that U.S. shipbuilding organizations have not utilized and therefore have not benefited from recent organizational theory knowledge of effective organizations. Existing U.S. shipbuilding organizations all tend to the mechanistic type. Unfortunately, the high efficiency and tightly controlled operations that the mechanistic type is supposed to provide are not being achieved. The bleak picture painted in this paper may not be representative of the currently surviving U.S. shipbuilding organizations and it would be reassuring to the author to hear of successes and meaningful improvements in the shipyards through the application of organization theory. The paper first discusses, generally, organization theory, its need and availability. Then an approach for its application is offered. Finally, the author describes his study of the structures and effectiveness of shipbuilding organizations.
Structural Performance Management of VLCCs— An Owner’s Approach
Authors: Melitz D. T. , Robertson E. J. , Davison N. J.
Published: January 2021

An owner's experience with structural design and performance of a wide range of ship types (oil tankers, gas tankers, semisubmersibles and tanker-based production systems) has enabled a new approach to be devised for assessing the structural durability of a class of five very large crude carriers (VLCCs). These vessels were built in the mid-1970s and are experiencing varying degrees of corrosion, dependent on their operational life. The approach adopted combined conventional ship structural design techniques with structural dynamics, as well as fatigue and fracture mechanics techniques more commonly used in U.K. North Sea offshore projects. The combination of these technologies has led to the development of a structural management strategy for the operation of these VLCCs. The strategy has three basic components: structural enhancement, structural inspection, and structural monitoring at sea. The formulation of each component is described in detail. Installation of a stress monitoring system on five ships (four VLCCs and one offshore monohull production vessel) over the past 15 months is described and typical results are presented. The importance of these results to the prediction of ship structural durability and their value in ship operation is discussed.
Wave Propulsion from a Flexible-Armed, Rigid-Foil Propulsor
Authors: Lai Peter S. K. , Bose Neil , McGregor Robert C.
Published: January 2021

A flexible-armed, rigid-foil (or "flexible fin") propeller was investigated as a wave propulsion device. Tests were done in head seas on a yacht model fitted with this propeller. The propeller reduced the peak heave and pitch motions of the model and contributed to forward thrust. Maximum thrust was obtained in waves with a length of 1.5 to 2.0 times the length of the vessel.
Data Buoy Aerodynamics
Authors: Wilson W. Brett
Published: January 2021

The National Data Buoy Center (NDBC) operates moored data buoys in waters around the United States, providing highly valuable environmental observations in real time from remote marine regions. Key among these observations are wind speed and direction, and, for that purpose, NDBC uses duplicate anemometers on each buoy for reasons of redundancy and data quality. A significant portion of the NDBC buoy array also measures the directional wave spectrum. Buoys so equipped, when also fitted with a fin on the mast, can produce wind speed and direction from the directional wave system output; however, the results, while good, have not been of sufficient accuracy to be of direct use meteorologically. It is postulated that better mast designs could reduce this inaccuracy. Toward that objective, this paper describes an analytical aerodynamic study, employing a custom-written numerical model, of existing and improved buoy mast configurations.
A Different Business Approach for the Navy Maintenance Process
Authors: Cieri Anthony M. , Horten Chris
Published: January 2021

The realization that there will be fewer assets and reduced budgets in the 1990's coupled with the continuing increase of ship maintenance costs throughout the 1980's requires a change in the technical and business strategies in which Navy maintenance is executed. Application of existing diagnostics and communications technology will provide our national assets with greater self-sufficiency as well as bringing real performance data shoreside to make more efficient business-related decisions in the way intermediate and depot-level work requirements are brokered. Integration of embedded training, as well as documentation and provisioning data, with the condition assessment technology shipboard will improve the ship as well as significantly reduce in size the structure of the shoreside community required to support our national assets. Several initiatives of varying complexity have been prototyped in fiscal year 1990 with test and evaluation in fiscal year 1991. These initial efforts provide a springboard to a strategy which integrates information from static and dynamic mechanical systems with damage control and combat systems into our existing ships by fiscal year 1995. Bringing this performance knowledge to the bridge will provide in service hulls a capability beyond what was ever expected and the corporate knowledge required to properly design the ship of 2010. The paper discusses the authors' vision of these evolutionary business concepts utilizing the application of today's technology.
Safer Transport of Oil at Sea: A Social Responsibility for Naval Architects and Marine Engineers
Authors: Noble Peter G.
Published: January 2021

To meet the urgent worldwide demand for safer ocean transport of oil within the realistic economic constraints of the shipbuilding and operating industry, naval architects and marine engineers confront a major challenge. This paper examines several tanker design alternatives as well as the restrictions imposed by both U.S. and international rule makers. The benefits of double-bottom/double-hull construction, based on an analysis of comprehensive grounding accident data, are discussed, and measures to limit the outflow of oil in the event of a spill are examined. Improved officer and crew training, more precise and up-to-date navigation/position-keeping systems, enhanced maneuvering capability with collision-avoidance sonar, and better shore-based traffic management of tank ships are among the author's recommendations to achieve the goal of safer transportation of oil at sea.
Ocean Engineering Education in the ‘90s
Authors: Ogilvie T. Francis
Published: January 2021

Engineering education at the bachelor's-and master's-degree levels is intended primarily to provide young people with the basic preparation for lifelong careers in the practice of engineering. Thus, in developing such programs, one must anticipate the demands that will be made of engineers over a period of several decades. In ocean engineering, this means that we must try to predict the kinds of ocean systems that will be required by society far in the future and then define the appropriate disciplines in which ocean engineers must be well-grounded. Accordingly, the focus of this paper is on the future of ocean engineering in the next century and on the basic knowledge that present-day students will need to succeed in that environment. Our ultimate objective is to enable mankind to build and operate systems in as well as on the oceans. Since underwater systems in the foreseeable future will depend on support from the surface, we must continue to develop the capability to operate in the hostile environment of the ocean surface. But we must also face the unique difficulties inherent in deepwater operations, including, for example, (i) our inability to communicate through the water, (ii) the lack of operational energy sources, (iii) high pressure, (iv) corrosive medium, (v) short lives of functional installations (especially moored systems), and (vi) problems of designing instruments and systems for monitoring both ocean operations and the environment itself. The hostility of the ocean environment will require that many operations be performed without human beings on site, thus creating the need for remotely controlled and autonomous systems. Such challenges are discussed in the paper, and the relevant fundamental disciplines are defined.
New Insights into Voith Schneider Tractor Tug Capability
Authors: Hutchison Bruce L. , Gray David L. , Jagannathan Sridhar
Published: January 2021

The emerging use of tanker escort in restricted waters requires tugs that are capable of rendering effective retarding and steering assistance to large ships operating in the 6 to 12 knot speed range. This paper presents findings from a coordinated program of model tests, computer simulations and full scale trials which have yielded new insights into the capabilities of Voith Schneider propelled tractor tugs. The emergency assist capabilities are shown as speed-dependent contours of the vector assist force in the coordinates of the assisted vessel. For tractor tugs the capabilities increase with speed. Simulations of tug assisted tanker maneuvers at 10 knots show that the tractor tug is more effective than a conventional tug in controlling the behavior of a disabled tanker.
A Resistance Study on a Systematic Series of Low L/B Vessels
Authors: Calisal Sander M. , McGreer Dan
Published: January 2021

Model resistance test results for a systematic series of low L/B, displacement-type vessels are presented. The UBC Series is based on West Coast seiners and trawlers. These vessels have low L/B and L/V⅓ values that are outside the range of existing model series data. A parent hull form was developed that has 14 percent less resistance and yet has the same displacement and deck area of a typical fishing vessel. A series of 13 models was generated by systematically varying L/B, B/T and Cb. Algorithms are presented for calculation of the resistance of similar small vessels for two loading drafts. Results of side bulb applications reduced the resistance of the parent hull at design speed by an additional 16.6 percent. The parent hull form is designed as a developable hull form.
Resistance Prediction of Planing Hulls: State of the Art
Authors: Almeter John M.
Published: January 2021

There are literally dozens of different ways that the boat designer can predict the resistance of planing hulls. The term planing hull is used generically to describe the majority of hard chine boats being built today. No single prediction method is good for all types of planing hulls. Some methods can be relied on to give good predictions for certain boats and other methods can't be relied upon at all. This paper is meant as a reference for designers in selecting resistance prediction methods for planing hulls. It describes numerous resistance prediction methods and gives their variable ranges and the type of planing hulls they are based on or are intended for. Inherent problems or limitations of the methods are stated. The concept of hull shape, which is often neglected in resistance prediction, and its important role are discussed.
The Grounding of Exxon Valdez: An Examination of the Human and Organizational Factors
Authors: Moore William H.
Published: January 2021

Just after midnight on March 24, 1989 the tankship Exxon Valdez ran aground on Bligh Reef inPrince William Sound, Alaska. The consequences of the accident were the loss of 258 000 barrels of crude oil resulting in substantial environmental and economic loss. The vessel possessed the best technologies available to the tanker industry and was the pride of the Exxon fleet. However, the complexity and the potential catastrophic consequences of using these new technologies is leading to the examination of a more critical element: the human factor. It has been determined that approximately 65% of catastrophic marine-related accidents have been the result of compounded human and organizational errors (HOE) during operations. Consequently, tanker operators and regulatory agencies have begun to realize the importance of examining the critical human factor element in tankship operations. Probabilistic risk analysis (PRA) procedures using influence diagramming are currently being developed to examine the effects of HOE in marine-related accidents. This paper examines (1) the human and organizational elements which led to the grounding of ExxonValdez, (2) structuring of the accident cause-effect relationships into an analytical framework, (3)methods for probabilistic risk analysis (PRA) of HOE in the accident, (4) changes in operational and regulatory policy in post-Exxon Valdez era, and (5) methods for determining HOE management alternatives for future tanker operations.
Development and Assessment of a Total Resistance Optimized Bow for the AE 36
Authors: Wyatt Donald C. , Chang Peter A.
Published: January 2021

A numerically optimized bow design is developed to reduce the total resistance of a 23 000 ton ammunition ship (AE 36) at a speed of 22 knots. An optimization approach using slender-ship theory for the prediction of wave resistance is developed and applied. The new optimization procedure is an improvement over previous optimization methodologies in that it allows the use of nonlinear constraints which assure that the final design remains within practical limits from construction and operational perspectives. Analytic predictions indicate that the AE 36 optimized with this procedure will achieve a 40% reduction in wave resistance and a 33% reduction in total resistance at 22 knots relative to a Kracht elliptical bulb bow design. The optimization success is assessed by the analysis of 25th scale model resistance data collected at the David Taylor Research Center deepwater towing basin. The experimental data indicate that the optimized hull form yields a 51% reduction in wave resistance and a 12% reduction in total resistance for the vessel at 22 knots relative to the Kracht bulb bow design. Similarly encouraging results are also observed when comparisons are made with data collected on two other conventionally designed AE 36 designs.
A New U.S. Coast Guard Support Concept: Maintenance and Logistics Command Atlantic Naval Engineering Division
Authors: Ames Fred L.
Published: January 2021

The U.S. Coast Guard reorganized all of its field support in 1987, centralizing these activities into Maintenance and Logistics Commands Atlantic and Pacific. These new commands provided exceptional opportunities for long-term improvements to the Naval Engineering support of the Coast Guard's cutters and boats. This paper describes the new organization and its strategy and goals to significantly increase the mission readiness of two thirds of the Coast Guard's fleet. Naval Engineering Division Atlantic is extensively using Total Quality Management (TQM) with some noteworthy results.