ABSTRACT

We built a one tenth scale model of a prototype of an oil recovery boat in order to conduct various water tank tests. After having made mechanical improvements, we finally carried out performance tests, using an actual boat on the sea waters near CTS of Nippon Oil Co.'s Kiire Terminal in Kagoshima Prefecture.

These tests proved that the system is capable of a very high performance in recovering oil of less thickness in spite of a certain amount of wind and waves.

This system recovered almost all of the drifting oil. The strong possibility was shown that the seas can be prevented from being polluted by the oil even on the occasion of an explosion of the oil wells on the sea bed and large-sized tankers' accidents.

INTRODUCTION

According to the statistics of the Maritime Safety Agency, there were 2,283 cases of pollution of Japanese territorial waters in 1972. Of these, pollution by oil accounted for about 87 percent, and such cases are tending to increase year by year. As a practical problem, there are numerous instances in which pollution from this oil causes great damage to Japanese coastal fishing grounds and recreation areas.

The authors had previously developed a floating- and submerging-type oil fence to provide against accidents involving the outflow of oil at oil loading and unloading piers. During the course of that research and development, it was realized that there was practically no device (at least not in Japan) for the recovery by physical means of oil spilled on the sea surface. After receiving a subsidy from the Japanese Ministry of Transport in fiscal 1972, we undertook the project of developing an oil-recovery device of high performance. This paper concerns the newly developed device for removing oil slicks from the surface of open water.

When a survey was conducted in the form of a questionnaire among Japanese government agencies including the Maritime Safety Agency, oil companies, electric power companies, and other private companies engaged in loading and unloading oil, one of the questions asked concerned the most important capabilities desired in an oil-recovery device. The replies given were as follows. (a) No oil should be left on the surface of the sea after the passage of the oil-recovery device. (b) Only the oil drifting on the surface should be recovered. (c) The oil should be recovered in a short period of time.

From this it was learned that the demands were for an evenly balanced fulfillment of these requirements under the conditions of a maximum 1.5-m wave height and about 15-m/sec wind velocity.

With these basic requirements in mind, research and development were conducted for it years from April 1972.

An experimental wave-forming water tank (circulatory type) was first completed and a prototype of the recovery device was built in the form of a fixed model on a scale of about one-tenth. This was placed between a catamaran of the same scale and the oil-recovery capability was ascertained.

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