It is very important for both naval architects and ship's officers to know the maneuvering characteristics of their ships. As the abilities of a rudder which controlls a ship can be determined clearly by analyzing the results of Kempf's zig-zag maneuver and directional stability of a ship also known by Dieudonn spiral maneuver, the importance of turning test which takes much time is recently apt to be neglected. But because the test can be executed comparatively more simply than any other maneuvering tests, it gives some informations on the directional stability, and turning characteristics may be expressed simply by the results of the test, it is still often performed. In this paper several assumptions are made to simplify the turning motion of a ship. The equations of initial transient phase, the radius ofsteady turning circle, and the center of the steady turning point are derived by using the hydrodynamic derivatives. And then the approximate method of drawing the turning circle geometrically is suggested.
There are two different assertions on the rolling error in the solid-controlled gyro compass which contains two rotors in its inner gyro sphere. One assertion is that there is a rolling error and the other is that there is no rolling error. This paper examines the rolling error caused by the centrifugal force by the experiment to reveal that the first assertionis reasonable, and it also attempts to explain qualitatively how the rolling error occurs. The Hokushin-Plath gyro compass is chosen as a model. The rolling error is examined by the swing test in various periods. From the tests, the following results are obtained. As long as the swing is continued under the fixed condition of the ship's heading, the swinging period and the amplitude, no error appears. In case the gyro compass is affected by the swingings except those of the cardinal planes, the error starts to appear only after the swing is finished and it is increasing slowly. It takes about 20 minutes for the error to reach its maximum value. The type of this error is a quadrantal one which makes the ship's heading high in the first and third quarters and low in the second and fourth quarters. But in each case the experimental maximum error is greater than the theorectical one.
The climate of a given region is determined by the combination of the various climatic elements. But among them, the temperature is the most important element to classify the climatic type. The author attempted to classify the climatic types in Korea by making a analysis of the characteristics of temperature distribution. To accomplish the study, the author analyzed the daily and yearly range of temperature, the warmest and coldest months, continentality and oceanicity, thermal anomaly, and relative temperature, etc. The data of 153 weather stations are used for the analysis of the above five criteria. As a result of the study, the climate of Korea can be divided into three types, namely, the continental, coastal and intermediate(or transitional) type. The Pronounced continental type is appeared in the northern part of highland area. And the coastal type is limited to the east and south coast areas, and the southern part of the west coast area. The continentality is larger, and the oceanicity smaller, than those of Siberia, Mongolia and the inland area of China where the continental climate is most remarkable in the world. The reason why the west coast area is more continental than the east coast area may be due to the terrain effect and the warm current going north along the east coastline.