Showing papers in "Marine Technology Society Journal in 1970"

Ultimate longitudinal strength

Abstract: Literature related to recent work in predicting ultimate strength of a ship hull girder is reviewed and discussed. Instability factors are presented for determining the maximum load such a girder will sustain in the sagging mode. Two bibliography sections are included: one for ultimate load for box structures and the other for primary and secondary structure associated with ultimate strength.

Cable systems under hydrodynamic loading

Abstract: A comprehensive review of the research investigation on the prediction of the motion of a cable system under hydrodynamic loading is presented. By chronologically and systematically presenting the past studies, the state of the art on the formulation of analytical models applicable to a wide range of problem areas is emphasized. Attempts to predict the steady-state configuration of a two-dimensional cable have been made since World War I. Recent studies have included the dynamic response of these systems to external excitation. The most general problem, which appears to be of widespread practical importance, requires a three-dimensional formulation. Some attempts at this approach have been pursued with limited success. The critical aspect of an analytical model is the inclusion of the hydrodynamic loading forces acting on the cable. A discussion of the physical nature of these forces and survey of existing analytical models for the loading function is included. A comparison with the limited experimental data available is also presented.

The Evaluation of Risk in Marine Capital Investments

Abstract: Future costs and revenues in capital investment opportunities can seldom be predicted with certainty. As a result, there is usually some doubt as to the outcome of an investment. The chance that an investment may not prove profitable represents the investors risk. This paper considers the problems which uncertainty and risk present in the evaluation of capital investments. Several traditional methods of dealing with uncertainty and risk are considered and shown to be deficient. A relatively new evaluation technique, which utilizes probability theory and computer simulation, is then described and its advantages highlighted. It is suggested that this technique will prove valuable in the evaluation of future marine capital investments.

Marine reheat cycles and systems evaluation

Abstract: In light of recent improvements in steam propulsion resulting from the application of the reheat cycle, it is the purpose of the paper to present general and accurate comparative data, to aid others in the proper application of reheat and to evaluate its gains. Schematic engine room arrangements for a symmetrical plant as well as one designed for improved economics are presented for possible application on twin-screw, high-utilization, fast-turnaround vessels. Various methods for specifying reheat performance are reviewed and reasons for a new method are given. A heat rate method is proposed and developed to help inprove standards of calculation and specification. Heat rate factors are provided on most engine room components to allow trade-off studies. Typical all-purpose fuel rate curves for five cycles are shown for 30,000 to 200,000 shp. Representative heat balance data are given to allow the marine designers to size or specify components by interpolation on a preliminary basis.

Reliability and Maintainability Analyses of Shipboard Systems

Abstract: The need for an increased emphasis on the reliability and maintainability characteristics of shipboard systems is discussed. Next, the current reliability and maintainability specification requirements are surveyed and their impact on the marine industry is reviewed. This is followed by a description and evaluation of the various types of reliability and maintainability analyses which may be applied to shipboard systems. Insofar as marine equipments are concerned, the major sources of data, their availability, and utility are also reviewed.

Ring propellers and their combination with a stator

Abstract: The paper discusses the features of propellers with an airfoil-shaped ring attached to the blade tips. Results of open-water tests of a series of ring propellers, propulsion tests with a tug model, and tests with a ring propeller/ring stator arrangement, as well as experiences with ring propellers in service, are reported.

The "manhattan" tanker test

Abstract: The summer 1969 and spring 1970 Manhattan Arctic Tests to obtain experience with the operation of a large commercial vessel in ice are described with emphasis on support to the test and implications for the future. Technical support included training of the Manhattan's senior officers, sea ice reconnaissance, and icebreaker services. Reasons are given for the conclusion that operational feasibility is reasonably well established, but economic feasibility is far from being determined.

Ship design and the computer

Abstract: The paper discusses current trends in computer-aided ship design, and the effects computer use may have on the scope and style of ship design.

Brief review of canadian technology in deep-sea automatically-moored buoy systems

Abstract: A two-stage system with a taut lower mooring cable and a slack upper mooring cable is considered to offer better over-all environmental performance and reliability than simple single-cable moored-buoy systems, either taut or slack. It is possible to arrange the two-member structure, so that each part is better matched to the conditions of its own local environment. The concept of automatic mooring is defined as the process of establishing without special manual adjustment such factors as precise length of mooring cable, compensation for cable extension under stress, and any detailed human involvements with the exact sequence of buoy deployment. Thus the buoy can be made to moor itself without special modifications regardless of ocean location and depth. The broad design principles and the salient technical features of this buoy system are described.