Tanker Size Research Articles

High V.I. Prevents Gear Scoring

SOME interesting facts and figures were given by Dr. Y. Takeda (Manager, Thermal Power Division, Kawasaki Heavy Industries Ltd.) in his paper entitled “Development of a Japanese Design of Marine Steam Turbine Plant” presented to The Institute of Marine Engineers on 25th November. This paper dealt with the remarkable increase in modern tanker size and this continuing tendency, necessitating improvements in marine turbine development design and manufacture.

On the Local Strength of a Super Tanker

As a general trend, the size of oil tankers is growing larger for economical reason. As a result, there have been arrived many technical problems involved in design of super tankers which must be solved. One of such problems is the local strength, and especially the buckling failure of web plates with slots for longitudinals of transverse rings is one of the most important items to study.In fact, in 1965, many super tankers suffered from damages of buckling failures. A most serious buckling failure occured at web plates with slots for longitudinals of transverse rings. These failures were recognized at tank tests or official trials. Then, ship designers increased the thickness of web plates and added suitable stiffeners or collar plates. Although actual failure of this kind has not been reported recently in Japan, there is still no sufficient support of theoretical investigation, except those by experiments.For theoretical analysis on buckling of web plates with slots, the authors developed a particular computer program based on the finite element method using triangular finite elements of conforming shape function. We also conducted several kinds of experiments and compared the results with those of the theoretical analysis. A quite good agreement was observed between them.

The Ethics of Using Large Tankers

COMMANDANT OUDET'S paper ‘The Black Flood’ is a masterly analysis of the circumstances surrounding the loss of the Torrey Canyon. We have come to expect contributions of this standard from Commandant Oudet, so much so that one wonders whether the sort of international tribunal which he advocates would be more effective in pointing to the lessons to be learned from casualties than Commandant Oudet's own work has been for many years past. In his discussion of the Torrey Canyon loss, Commandant Oudet raises the question of whether the size of tankers should be limited. This question has been voiced elsewhere with the implication that, economics apart, the trend towards larger and larger tankers is a bad thing. It deserves a more detailed study.To simplify this study a hypothetical case is considered in which a company has to transport oil at a rate of 200,000 tons per week between two ports where the round voyage takes two weeks. In theory this could be done using one 400,000-ton tanker, two 2000,000-ton tankers, …sixteen 25,000-ton tankers, …forty 10,000-ton tankers…. Economic considerations favour the use of large tankers provided there is sufficient water at the two terminals and enroute, but is this morally justified in view of the possibility of repetitions of the Torrey Canyon incident?

On the Strength of Horizontal Girder on Transverse Watertight Bulkhead

Along with the recent tendency to the increase in size of oil tankers, the scantlings of hull structural members, especially primary supporting members, have become very large. Also, these members are subjected to great loads, and a considerably high stress may occur locally if the scantlings of the structure are not sufficient.As one of the series of studies to cope with the increase in size of oil tankers, the authors try to investigate the strength of horizontal girders of a 120, 000 DWT tanker by comparing the stress measured on an actual ship with the stress calculated by an electronic computer.The results of stress analysis coincide considerably well with the stress measured on an actual ships, showing that the calculation method described below is fairly good.This paper also discusses the strength of horizontal girders in various loading conditions, the effectiveness of center line vertical web and the effect of transverse rings neighboring watertight bulkheads on horizontal girders.

Sea Pilotage Today: II—The Problem of Super-Tankers

The problems posed by the ever increasing size of tankers are not those of ‘bigness’ alone, or even at all. Southampton has been accustomed to the world's largest ships since the turn of the century; such as instanced by the Aquitania of 43,000 tons gross of pre-1914, the Majestic, 53,000, Normandie, 73,000 and Queen Mary of 83,000 between the wars, and since, the Queen Elizabeth, 85,000 and more recently France, the longest ship in the world, at 1043 ft. All these ships, however, are quadruple screwed, and for that matter there is not a cargo or passenger ship of more than 14,000 tons gross coming to the port which is not at least twin-screw. It had always been supposed that there was a limit to the size of ship which could be safely manœuvred with a single screw in confined spaces. The advent of the single-screw mammoth tanker, turbine engined, has put a new angle on this problem, but pilots generally are not at all sure that this is in the best interests of safety.