In view of design and evaluation of systems, the author considered the fundamental composition and the functional relation among each components of the position fix system, figuring the reliability diagam. Consequently the system reliability P was shown as P={P_E∧(P_O∨P_C∨P_R∨P_S∨P_F∨P_L∨P_D∨P_W∨P_N)∨P_E}, where P_E, P_O, P_C, P_R, …P_N are reliability of dead reckoning, celestial navigation, coasting, radar navigation…and satellite navigation subsystems respectively.

抄録全体を表示

The studies are based upon the measuring records taken by the Japan Maritime Safety Agency at 12 monitoring points within the coverage of the Kita Kyushu Decca Chain during about one year (1969-1970). Additionally, supplementary measurements were carried out at two points during 72 hours. These observations were made by following data ; 6 days every month, every minute and 1030-1130 (daytime). Constant deviations of both each pattern and each point were obtained. The characteristics of these deviation were correlated each other at the next points in the Red and Green pattern. Monthly standard deviation showed that±1-3 cel corresponded to about ±10m near the base line except the point where to poor propagational conditions. Of course, the nature of the deviation suggested that the propagation velocity used were unsuitable, the reasons why of these phenomenon were presumably affected by the mountaineous profile along the each path. Especially a large amount of deviation of Purple pattern at Hososhima might be influenced by the nature of the route which across the sea and the steep mountains several times. The meteorological conditions will be affected the deviation and these introduced two types of variation. Approaching the front, high pressure and typhoon, a peculiar variation will be occured synchronously at several points.

抄録全体を表示

In fall of 1970, Decometer readings were carried on simultaneously at four points, every 10 min. in daytime and 5 min. at night during 72 hours continuously. The consideration of selection of these points was made carefully in order to analysis data under uniformal propagation conditions. The constant deviations at each point and pattern were found respectively, but the correlation between the distance from the transmitter and the deviations could not ascertain clearly. Because the author considered that a large amount of deviation at each point might be introduced from the neighbouring interference on account of geological position. In the case of Red pattern, however, 3 points are positioned nearly on the great circle, and also, the deviation increased was proportionaly to the distance from the transmitter. The stability of Purple pattern is ±2-3 cel during, daylight, correspond to the distance in about 7-12m. To the contrary, from the transient time or so the Decometer readings will be oscillate gradually and progressed to night variation like the sine wave. These phenomenon are presumably introduced from the contamination of the skywave. Since the night variation is a large, the phenomea was caused by the variaton of the virtual height. The phenomena above could not analysed at the present time.

抄録全体を表示

The servo type SMD compass has been reported by the authors before. This time, two pairs of SMD bridges are used, one being fixed fore and aft and the other transverse. Each output from the SMD bridge is given to the oscilloscope acting X-Y, and then the brilliant line showing the direction appears on the CRT. In this paper, theoretical and experimental investigations on the CRT presentation type SMD compass are reported.

抄録全体を表示

A collision avoidance system is devised which is composed of a ship-borne radar and a conventional VHF communication system with some additional devices. Ship-borne radars and VHF communication systems are used quite widely today. The functions of the system are listed below ; (1) collision warning by a buzzer which is equivalent to a horn of a car. (2) identification of a target with which a collision may occur by giving a mark on the radar scope as well as identifying lamp display. (3) exchange of information on manoeuvrings and others through VHF telecommunication. An evaluation test at sea was executed in the vicinity of Port Yokohama where "Noji-ma", a patrol ship, was employed as the target and "Sumida", also a patrol ship, was calling station. The functions of the system were almost satisfactory and the covered range was up to 3.5 miles for the range of "Low Sensitivity" of the radar receiver. However, interferences from other radars as well as other VHF transmitters were obser-ved occasionally, since the congestion of the ship traffic as well as electromagnetic wave are heavy in the port. The tested system has this shortcoming, however, the authors feel that if the system is produced very economically, its merits are beyond its shortcoming.

抄録全体を表示

The technics of echo-sounding from the surface of ice, which had been tried at the frozen lake, Harunako, were applied to sounding at locations near Syowa Station in Antarctic in 1967 and 1968. This is very important for the research of topography. The echo sounder was designed and manufactured to be usable at the polar region. In order to make the transducer contact with the surface of ice, grease was used in stead of water. The maximum sounding was the depth of 405m through the ice the thickness of which was 140cm. The precise topographical charts were drawn with this echo-sounding and the technics of determination of accurate sounding positions on the surface of ice.

抄録全体を表示

An officer on duty on a fishing vessel was watching a drift net or long-line going a-drift after it had beeh set. Whenever, if he can estimate the relative position of the ship in relation to her fishing gear during drifting without recurring to an object (flag, light, reflector, radio buoy), he can employ the method to watch the gear effectively. For example, the authors made the experiment with the drifting of the Oshoro-Maru, a fishery training ship of Hokkaido University, in the Bering Sea, and tried to express the direction and distance of the drift by parameters with the ship's head and wind velocity.The experiment 1. The corner reflector connected to the drift net was selected as the datum point of the experiment. In this case, the reflector was allowed to drift together with the ship according to currents and waves, but it felt no effect from the wind in spite of the movement of the ship. 2. The observers on the ship measured the distance and the bearing of the reflector by radar every 30 minutes and calculated the drifting by solving the triangls. Observations were made several hours each day for 14 days. The results are as follows: 1. The relation between the wind velocity (W) and the drift is shown in Fig. 2. 2. The relation between drifting coefficient (K) and the ship's head (α) is shown in Fig. 3. Accordingly, the drifting velocity (U) is expressed by the following equation, U=(a-bα)√<S/Sw>W. 3 .The direction of drifting is closely related to the ship's head (shown in Fig. 8), accordingly, the drifting direction (β) is expressed by the following general equation, β=a+bα, and the coefficients a and b are based upon the ships' drifting characteristics. 4. Consequently, if one knows the drifting characteristics of his own ship, he can estimate the position to which the ship has drifted.

抄録全体を表示

In this paper we describe problems on a controllability of ships when very large vessels proceed through the middle-channel of the strait of Kurushima, and also as to whether it is safety enough. An output of irregular yaw motions of ships caused by a turblent flow was replaced with an input of Equivalent Rudder Angle δ_e, which is expected to generate the same yaw motion of ship, and the equivalent rudder angle was used as a new guidance to estimate the yaw angle of very large vessels in the turblent flow. In order to obtain the steering-pattern that eqauls the turblent flow effect, tests by full sized ship were carried out on a training ship (G. T. 360t) and passenger ships (G. T. 2, 900t). From the results simulated for very large vessels by using a digital computer and the experimental data, it can be considered that the ship-maneuvers in the turblent flow are not so difficult as it is imagined.

抄録全体を表示

Authors dragged JIS-stockless anchor (18.63 kg) and JIS-stock anchor (19.04 kg) at a constant speed 25mm/s in mud sea bottom. The results obtained from these model test were given as follows ; 1) When JIS-stockless anchor dropped vertically from a height of 1m, a ratio of dragging pull to anchor-weight reached to 4.16, but in a short time its ratio decreased to 1.23. Also the ratio in condition when the anchor was able to bury reached to 5.43, and the instability occured within the dragging distance of 4.2 times anchor-length and then the ratio decreased to 1.49. 2) The dragging pull of conventional stock anchor indicated a constant value 5.38 times anchor-weight and it had never turned on a axis of anchor-shank. It may be quite all right to considered that JIS-stockless anchor in mud bottom is not trip, as often pointed out.

抄録全体を表示

Look-out should be vigilant, even if other ship has no Lights, it may be negligence not to see and avoid another ship. An overtaken vessel is not ordinarily obliged to keep watch astern so long as she showing a proper stern light, holds her speed and course, and taken any action to avert collision.

抄録全体を表示

There seems to be some confusions in construing, applying and obeying Article 12 of Japan Port Regulations Law. So this paper offers, tentatively, the conditions under which to apply this Article and the points to be agreed upon borh in construction and practical operation.

抄録全体を表示

Comparing the operation of liner boats with that of timber carriers, the authors have tried the rationalization of timber carriers. During one round voyage of American-log-carriers and Lauan-carriers, their operations are examined. Besides conditions of operations at Nagoya and other discharging ports are examined. The number of ships for statistics was as follows: Nagoya Others American-log-carriers 66 54 Lauan-carriers 263 49 The term was about one year, from Nov. 1969 to Oct. 1970. As the result of investigation, they found that the great obstacle of rationalization was the high ratio of anchoring hours to one round voyage. Especially the shortage of anchoring hours at discharging ports was necessary. The main cause of the extension of anchoring hours is that the ratio of waiting hours to moor and waiting hours to discharge cargo is high. The solution of these problems are enlargement of timber ponds, consolidation of port facilities, rationalization of cargo-working and security of skilful laborers.

抄録全体を表示

The authors brought forward a definition of the meeting in the marine traffic flow. According to their definition, the encounter, one situation of the meeting, is a situation that the course of a certain ship is the value between plus 135 degrees and plus 225 degrees from the course of the reference ship, the crossing, another situation of the meeting, is a situation that the course of a certain ship is the value between plus 45 degrees and 135 degrees or between plus 225 degrees and 315 degrees from the course of the reference ship, and the overtaking, the other situation of the meeting, is a situation that the course of a certain ship is the value between plus 315 degrees and plus 45 degrees from the course of the reference ship and the speed of the reference ship is greater than that of a certain ship. They obtained the number of the meeting from the simulation of the middle of Tokyo Bay. Farthermore, they proposed the definition of the randomness and obtained the values.

抄録全体を表示

1962年から1969年までの8年間に関門海峡で発生した衝突海難について分析した結果を要約すると次のとおりである。1)関門海峡で発生した全海難は年平均65件で,そのうち衝突および乗揚海難が72%を占めている。種類別海難の趨勢は,衝突海難の場合増加傾向をたどつており,乗揚およびその他の海難の場合横ばい状態である。2)衝突海難の発生地点は部崎沖,早靹瀬戸の門司崎寄り,門司港内,大瀬戸の彦島寄りおよび六連島泊地に集中している。3)各水域の衝突危険度を幹線航路の長さ1浬当りの衝突海難発生率に基づく指数(東部水域を100とする)で評価すると,早靹瀬戸500,中部水域408,大瀬戸150,西部水域116である。4)水域別の衝突海難発生件数の経年的趨勢は西部水域では増加傾向をたどつており,東部水域でも増加傾向がうかがえる。他の水域では横ばい状態である。5)西部水域では3,000トン以上の大型船の衝突発生率が高く,早靹瀬戸および大瀬戸では100〜1,000トンの比較的小型船の衝突発生率が高い。6)衝突事故船の船型は急激に大型化している。7)衝突事故船の船型は71%が1,000トン未満である。しかし趨勢としては1,000トン未満の小型船の衝突海難が,ほぼ横ばい状態であるのに対し,大型船の衝突海難が増加している。8)関門海峡通航船の1隻当りの衝突事故率(p)と総トン数(x)との関係は,次の指数関数で表わされる。p=0.46x^<0.59>×10^<-5>9)衝突海難は夏期に少なく,冬期に多発する傾向がある。10)衝突海難は4〜6,時および16〜18時に最も多く発生している。2時間単位でみた船舶交通量と衝突海難の発生件数との間には,ほとんど相関は認められない。11)夜間は昼間にくらべ衝突海難が多発する傾向があるとはいえない。しかし夜間交通量が昼間にくらべ激減することを考慮すれば,夜間通峡船の衝突事故率は昼間の2.5倍である。12)停泊船との衝突海難は全衝突海難の17%を占め,大部分が門司港内と六連島泊地で発生している。門司港内では昼間,六連島泊地では夜間の事故が多い。13)最近六連島泊地で,停泊船との衝突事故が急増している。

抄録全体を表示