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1983Volume 18Issue 2 Pages
59-72
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
JOURNAL
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[in Japanese]
1983Volume 18Issue 2 Pages
73-74
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
JOURNAL
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[in Japanese], [in Japanese]
1983Volume 18Issue 2 Pages
74-82
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
JOURNAL
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[in Japanese], [in Japanese], [in Japanese]
1983Volume 18Issue 2 Pages
82-87
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
JOURNAL
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[in Japanese]
1983Volume 18Issue 2 Pages
87-92
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
JOURNAL
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[in Japanese], [in Japanese]
1983Volume 18Issue 2 Pages
92-96
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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[in Japanese], [in Japanese]
1983Volume 18Issue 2 Pages
96-98
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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[in Japanese]
1983Volume 18Issue 2 Pages
99-103
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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[in Japanese], [in Japanese]
1983Volume 18Issue 2 Pages
103-112
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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1.New Stern Tube Sealing System Free from Sea Pollution
Yuichi Hirao, Hisashi Yoshida, Masaki Nishino, Shigeo Matsumoto
1983Volume 18Issue 2 Pages
113-116
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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Recent very strict regulations for the control of pollution in ports and waterways influence the stern tube sealing system. Conventional sealing system is based on the concept that lube oil pressure in the stern tube is kept always higher than sea water pressure, thus the propeller shaft and the stern tube bearing are not damaged when the seal is out of order because sea water ingress to the stern tube is prevented by lube oil pressure though lube oil leaks out. This concept is, however, no more rigid today.
The new type of sealing system is based on the idea that lube oil pressure in the stern tube is always lower than sea water pressure, whereby complete no oil leakage is achieved and sea water ingress into the stern tube is also checked step by step. The paper says features of the seal combined with the lube oil piping system and results of the laboratory test simulating possible various situations on the vessel.
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Yuichi Tomono, Hiroo Tanoue, Shoji Shiomi
1983Volume 18Issue 2 Pages
117-120
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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Since the oil-lubricated stern tube system was applied on the first Japanese ship in 1964, the oil seal type of sealings have been commonly used up to date. From the point of the prevention of oil pollution, the sealings have been improved according to the severe demand of reliability. That is, the rubber material of seal rings have been converted from Buna-N (NBR) to special fluoric rubber (FKM) and applied for smaller ships. On the other hand, the sealing structure is compact, and recently the aft sealings of four lips with a spare seal ring mainly tends to be adopted in order to get higher reliability on the prevention of oil leakage. Therefore, the sealing structure of four lips type and the rubber material developed recently are generalized, reported herein.
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Seiji Yamajo, Nobuhiro Hayami
1983Volume 18Issue 2 Pages
121-126
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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On the oil lubricated stern tube seals, the lubricating oil in stern tube leaks into sea when sealing rings are damaged by accident and the oil leakage causes the sea water pollution. It is necessary to remove the leaking oil to prevent the sea water pollution and experimental studies have been carried out to remove the leaking oil.
The flow of leaking oil at the outside of stern tube was observed on a test stand to find out the effective removal method. Then various experiments were carried out to remove the leaking oil from the outside of stern tube seal and also from the inside of stern tube seal respectively.
It was found from the experiments that the leaking oil could be well removed from the oil chamber between No. 2 and No. 3 sealing rings on the aft seal. Then an oil removal equipment was designed to remove the leaking oil efficiently and it was confirmed through the test that the equipment had sufficient performance.
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[in Japanese]
1983Volume 18Issue 2 Pages
127-131
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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Yoshio Sasaki, Nobuhiro Hayami, Kiyoshi Moriya
1983Volume 18Issue 2 Pages
132-141
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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To make clear the effect of weld repair on the fatigue strength of marine propellers, a series of tests has been carried out with the base metal and the welded metal under the condition of 3% synthetic sea water, plane bending load and stress ratio
R=0.4 in which actual propellers are in service.
The large specimens were manufactured of which measurements are 700 mm in length, 200 mm in width and 50 mm in thickness, to make the stress gradient of specimens the same with that of full-scale propellers. As to the material of specimens, two kinds of propeller materials were used such as Ni-Al-bronze and Mn-bronze.
There were no differences in the fatigue strength between the base metal and the welded metal. Moreover the residual stress around the welded zone was successfully measured and the fatigue fractures of those materials were observed by the fractography.
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Toshimasa Saitoh
1983Volume 18Issue 2 Pages
142-153
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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The recent growth in propulsive power of ships has resulted in cases of severe damage to the stern tube bearings and the sealing rings. In most cases, the shaft alignment analysis has been still only carried out under non-operating condition. This static alignment condition is considerably effected by some external factors, such as propeller forces and moments, double bottom deformations, bearing flexibility and thermal influence.
The paper discusses the theroretical and experimental study of the dynamic shaft alignment in service loading of stern tube bearings. The distortion and bowing of the tail shaft under the influence of the propeller forces and moments is taken into account of the analysis of the stern tube bearing performances.
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Yukio Akutsu, Jun'ichi Mitsui
1983Volume 18Issue 2 Pages
154-162
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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In order to achieve energy savings, ships are now being designed with larger propellers operating at lower speed. Such designs impose a heavier load on the stern tube bearing. The shaft alignment calculations have been made taking oil film characteristics of stern tube bearing into consideration. The oil film characteristics have been analyzed by the finite width hydrodynamic theory applying to the curved shaft in the stern tube bearing.
This theoretical analysis has made it possible to elucidate the oil film characteristics of the stern tube bearing. The optimum width-diameter ratio of the stern tube bearing at lower speed has been also obtained by this analysis.
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Michio Takahashi, Mitsuru Umeno, Noriaki Higasa
1983Volume 18Issue 2 Pages
163-168
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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From ship hull response, viz, response amplitude operator and sea waves spectrum of ISSC, ship hull response in sea waves has been obtained, and the short term prediction method about ship propeller immersion has been derived.
Then, in the case where encounter conditions with several seaways are given, the long term prediction method has been offered.
The theoretical analysis results as to a 30, 000 gross tons bulk carrier with lower revolution larger diameter propellers have been shown.
(1) In the short term prediction calculation, the coming out probability of propeller blade tip over sea surface is the largest at a certain wave mean period.
Above the period the probability is larger at following sea sailing than at the case of head sea sailing.
In the case of head sea sailing, the probability at the case of lower speed sailing is smaller.
(2) In the long term prediction calculation according to Walden's observation data for the North Atlantic Ocean, the propeller tip coming out probability increases as propeller diameter increases. The probability becomes 18 times larger when propeller diameter increases by a factor of 1.5.
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Yutaka Hiromoto, Yasuaki Ishihara, Minoru Yoshida
1983Volume 18Issue 2 Pages
169-174
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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This is the experimental report showing how hull vibration was reduced by the use of highly skewed blades (H. S. blades) from measuring hull vibration, in case of replacing conventional blades with H. S. blades on the ship equipped with controllable pitch propeller (CPP) .
The following points have been found from the result of vibration measurement.
Hull vibration has been reduced to half of the existing one by utilizing H. S. blades as a whole. Especially, the blade number frequency component of vertical acceleration has been reduced conspicuously.
In case of CPP, H. S. blades with ahead blade angle can reduce hull vibration effectively, but they can not reduce hull vibration at all at the time of specific operation of the ship such as astern.
H. S. blades to twin screws ship can reduce hull vibration more effectively than expected, compared with H. S. blades to single screw ship.
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Shigehiro Homori, Nobuhiro Baba, Yasuo Sasaki
1983Volume 18Issue 2 Pages
175-180
Published: February 01, 1983
Released on J-STAGE: December 08, 2010
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In recent years, the highly skewed propellers tend to be used for the prevention of the growth of ship vibration and noise. On the other hand, however, the blade strength of the highly skewed propeller under the ship operating condition has not been measured up to the present time, in spite of the need for the judgement on the blade strength. Therefore, the authors measured the blade stresses of the highly skewed propeller which was fitted on a' Pure Car Carrier.
After analyzing the measured data, it has been found that the maximum principal stress induced on the pressure surface of the blade at the point of 0.4 R with 90% camber length from leading edge became maximum in value when the propeller chip clearance became minimum.
Furthermore, the measured principal stress mode within one revolution has been compared with the calculated result by the FEM analysis and the both have a similar tendency in the mode.
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Koji Sawano, Hiromu Yoshii, Kazutaka Kikuchi, Shoji Mochizuki
1983Volume 18Issue 2 Pages
181-187
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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This paper reports on a CPP Control Back-up System utilizing a CRT, which has been newly developed by NKK and installed on the NKK's new energy saving ships equipped with PC engines and controllable pitch propellers (CPP) .
This system consists of a CPP control system featuring automatic load control, constant ship speed control and constant SHP control as well as a data display system utilizing a color graphic CRT which displays the characteristics of the main engine and the CPP, the operating point of the main engine and various actual operating data of the main propulsion system.
This system makes it easy to perform fine aiming of such operation targets as energy savings, high operating rates, low maintenance costs, etc.
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Shigemitsu Nakamura, Susumu Murakami
1983Volume 18Issue 2 Pages
188-192
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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Recently, it has been increased in number to install modern long stroke diesel engines with small cylinder numbers for marine propulsion in order to gain fuel saving and simpler maintenance.
For adoption of this type of engine, however, a through investigation of vibration in engine room is necessary at the design stage because of its tendency to cause vibration problems.
This paper describes difficulties of vibration on modern long stroke diesel engine and its countermeasures.
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[2nd Report, Friction Loss at Oil Lubricated Stern Tube]
Propeller and Shafting Committee of MESJ
1983Volume 18Issue 2 Pages
193-197
Published: February 01, 1983
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The friction loss at oil lubricated stern tube has been estimated by summing up the following heat values.
(1) The heat values at bearing have been estimated from the heat analysis of temperature measurement data under the maximum continuous output steady condition at the sea trial.
(2) The heat values at seals have been estimated from friction torque between seal ring and liner.
As a result of heat analysis, the loss of horse power was found to be 0.1-0.3% of maximum main engine output.
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Propeller and Shafting Committee of MESJ
1983Volume 18Issue 2 Pages
198-203
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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Since the past year, the dry contact push-up and pull-off method, which is carried out with the condition of metal contact on cone part had been applied to connect the propeller shaft with taper fit type propeller.
However, this dry contact method had some technical problems.
Recently, to resolve the technical problems, the method of push-up and pull-off of propeller by oil injection into the oil grooves provided on the inner surface of the propeller boss, has become popular in lieu of the dry contact method.
Taking the above into consideration, the Propeller and Shafting Committee has done studies and reported about the procedure for push-up and pull-off of propeller by oil injection method, the relation between push-up load and expansion pressure, the analysis for actual results and the method of application to actual design.
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Propeller and Shafting Committee of MESJ
1983Volume 18Issue 2 Pages
204-207
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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It is well-known fact that the cathodic protection by use of zinc anodes or aluminium alloy anodes has been applied to the shafting and its propeller.
There are many reports on the errosion or corrosion of the shafting and its propeller. However, we have had very little information on the grounding device of the shafting.
According to our own investigation and information from the ship's operators and shipbuilders in Japan, the following guidances have been obtained:
(1) It is necessary to protect the shafting against corrosion, when the shafting has a Mn-Br propeller and an oil bath type stern tube bearing or the shafting has a sea water lubricated stern tube bearing and its propeller shaft is fitted with a copper alloy sleeve.
(2) There are many cases where the shafting having a Ni-Al-Br propeller and an oil bath type stern tube bearing is not provided with a grounding device.
(3) The suitable materials of a slip ring and a brush to be used for the grounding device are as follows:
Slip ring ..... Copper, Silver etc.
Brush ....... Metalic carbon, Metal brush
(4) The contact surface between the slip ring and the brush of the grounding device must always be kept clean.
The above Item (4) is one of the most important factors for the effectiveness of the grounding device. Thus, it is expected that the grounding device which is free from maintenance work will be developed in future.
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Propeller and Shafting Committee of MESJ
1983Volume 18Issue 2 Pages
208-212
Published: February 01, 1983
Released on J-STAGE: May 31, 2010
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Propeller and Shafting Committee has made the standard of lubricating oil piping diagram for stern tube bearing and oil sealing device.
Planning this standard, inquiries about recommendations of seal maker in Japan and design criteria of ship builder as member of the committee have been made and these have been considered in this standard.
This standardized piping diagram is applicable to oil lubricated stern tube bearing and standard type sealing device which is not given special contrivances for preventation of oil leakage outboard.
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