2) One of the critical items among the energy conservation measures is the scheme to enhance propulsion efficiency through improvement in hull design. Because the many vessel types such as VLCCs and container ships have already achieved a high level of propulsion efficiency, it is difficult to achieve further explosive gains in energy conservation through this scheme. However, with regard to frictional resistance, the largest element of resistance, research and development aimed at finding practical and effective reduction schemes continues. This research includes surface treatment techniques such as microbubbles, air films, self-polishing paint coatings, and elastic films.
2. Ship Safety and Reliability
Since the latter half of the 1980s bulk carrier accidents at sea have been a regular occurrence, debates on the safety of bulk carriers has been led by the IMO and the International Association of Classification Societies (IACS). A legal framework regarding schemes to strengthen safety requirements is beginning to emerge. Additionally, as accidents involving aged oil tankers have continued to contribute in a significant way to oceanic pollution, the exclusion of these socalled substandard vessels that fail to meet international standards and the strengthening of port state control (PSC) have become critical issues for the world mercantile marine.
2-1 Hull Inspections and Maintenance
In order to ensure their safe navigation, regular inspections and structural surveys of bulk carriers and oil tankers have been made more strict in the areas of inspection scope and method. The 1994 revision of the SOLAS Convention has made compulsory the "Enhanced Survey Program(ESP)" for oil tankers and bulk carriers.
Moreover, as one link in the enhanced PSC policy, the Japanese proposal to mandate the entry of limits to the deterioration of plate thickness in the Hull Structural Plating Thickness Measurement Report of the flag country has been adopted as part of the 1997 revision of the SOLAS Convention. While evaluating the safety of the structural strength of vessels through deterioration in plating thickness involves many technical issues and requires careful examination, basic research in this area is underway.
2-2 Hull Corrosion and Fatigue
Through recent sophisticated analysis, it has become clear that the cracks in high tensile steel side longitudinals of large oil tankers which occurred in the late 1980s were fatigue cracks emanating from where stress concentrates and caused by fluctuating wave pressure. As a result of this analysis, the structural system of newly built large oil tankers has been modified so as to ease the concentration of stress and thereby enhance the safety of ships. Also, basic research is now underway to explore changes in fatigue strength in a corroded condition. All of the data on fatigue capacity heretofore were collected in an uncorroded condition.
Recently it has been pointed out that the conditions of corrosion occurrence in the crude oil tanks of tankers are different from previously observed, while increases in the degree of corrosion spread and changes in the form of corrosion have also been noted. In order to come to grips with this situation, research and development aimed at establishing guidelines on anti-corrosion measures is being conducted.
2-3 Hull Strength Monitoring
Hull strength monitoring is one method of supporting the safety of ships in service, and recently it has been the subject of particular attention. At the IMO, establishment of a Hull Strength Monitoring System designed for bulk carriers is under review, while ship classification societies have begun issuing special class notations for vessels that have been equipped with this kind of Hull Strength Monitoring System.
Presently the development of more advanced types of devices is being conducted. These include devices that will relay monitor information at high speed from ship to land and systems that will comprehensively monitor information related to factors like wave conditions and situations like the generation of stress in structural members.
2-4 Modernization of Ship Operation and Establishment of Management Systems
Raising the level of reliability and automation of various systems on board in order to achieve labor savings has been a subject of study over the past few years. Particularly on Japanese vessels, as a result of both high Japanese labor costs and skilled seafarers scarcity, there has been mounting demand for the development of navigation systems so that even unskilled seafarers can operate them safely. Systems that allow safe and simple operation by anyone through the employment of automated systems in conjunction with expert systems based on the knowledge of highly trained seafarers are now being explored. One of the tasks is to achieve a simple, highly dependable and easy-to-use system which at the same time incorporates the latest in fuzzy logic and neural network theories.
Also, recognition of the need to begin grappling with the software aspect of the matter as an important component of safe operation has begun to grow. As a result, in 1994 the ISM Code calling for the establishment of a ship operation management system was adopted by the IMO; the code was put into effect in July 1998.
Under this new ship operation management system, the shore versus on-board duties, responsibilities, authority and mutual relationship are stipulated clearly as is the requirement to equip the ship with a Safety Management System (SMS) for the purpose of ensuring safe ship operations and environmental protection.
In order to establish an SMS that is feasible to implement, the shipping and shipbuilding industries are undertaking joint research concerned with finding the most appropriate operation system for a ship. The research explores, from both a hardware and software perspective, the issue of what constitutes a ship that is easy to operate.
