The advanced researches of the ship's motion in the seaway can predict the heaving, pitching and slamming of ship's motion. The researches as of today are that of displacement type such as a small typical fishing boat and U, UV and V bow ship forms under low speed. In recent day, the study of behaviours of high speed planning boat in the regular waves has been carried out by Bessho [5]. The calculation about behaviours of a high speed vessel in the longitudinal regular waves is calculated by Ordinary Strip Method in this paper. The data of the results were discussed and compared with Bessho's results. The conclusions deduced from this study are as follow, (1) The acceleration of motion calculated by the O.S.M. is similar with Bessho's data for the Fn 0.5 (2) The amplitudes of the behaviours of motions take peak at 1.0<λ/L<1.4.

Echo sounder and Doppler sonar are to theultra-sonic transducers for measuring the depth and the ship's speed respectively. To measure the depth and speed with a single transducer, it is required to control the ultra-sonic beam to optional direction. In the past, the direction of the transducer itself is varied, but such a method provoked much problems in the mechanical design of the equipment. This paper deals with the method to control beam direciton by the phase control of the plural arrangement of transducers, and the results are studied by a computer simulation. The remarkable results of the study is condensed as follows; 1. The greater the interval of arrangement between transducers, the sharper the radiation pattern is, but in this case, the level of undesired sidelobe is also increased. 2. The control of radiation pattern up to 60 degree can be achieved by an adequate arrangement of more than 10 transducers. 3. It is shown that a simultaneous measurement of both depth and speed can be achieved by alternating directivity of the pulse by the method proposed in this paper.

The writer has attempted in the present article first to investiqate whether shipping industry is poor countries' business more favourable to them, compared to wealthy nations in terms of comparative cost of operation and to analyse how can developing conntries afford to maintain a modern fleet; secondly to examine the economic aspect of the situation created by the UNCTAD V held in May this year, at which passed a resolution demanding "the right of all countries to an equitable participation in the carriage of cargoes generated by their own trade"; and thirdly to adduce conclusions. The article contains six chapters; chapter I is the introduction on the subject under examination; chapter II provides background information on the structure of the industry and of the operating cost of ship; chapter III addresses itself to the legal backgrounds of ensuring free transfer of resources among nations and free competition of shipping; chapter IV deals with the recent development of shipping nationalism of developing countries at the UNCTAD; chapter V discusses division of labour in shipping and in particular the survival mechanism of high-cost countries; and chapter Ⅵ sets forth conclusion.onclusion.