Stresses in the propeller bosses induced during the shrink-fit process are raised at the fillets of the blades, and experiments carried out hitherto show that stress concentration factor is about 2.
Main purpose of this paper is to estimate these concentrated stresses quantitatively.
Using the finite element method, stress analyses were carried out for various shapes of simplified two dimensional bosses. Input data were fully automatically generated, and so the number of blades, width of blades and outer diameter of bosses could be varied parametrically without any difficulty.
As a result of this investigation, the following equation was obtained for the standard types of bosses and blades,
α =5.25η²-2.88η+2.09
where
α = stress concentration factor
η = total width of blades over outer periphery of the boss
Propeller blades have also the strengthening effect on the boss rigidity, and the gripping force of the boss is raised by the blades. Equations which can roughly estimate this effect were also proposed.
Three dimensional photoelastic models of the bosses with blades were made by casting, and analyzed experimentally for comparison with the numerical results of the two dimensional models, and a fairly good agreement was obtained.

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This paper is intended to provide full scale test results of the newly designed and manufactured marine epicyclic propulsion gear of gear ratio about 5.3 for the 15000 ps unit, in order to make the reduction gear much smaller in size and lighter in weight than those of the conventional type.
Before designing the gear, basic investigations of gears concerning equal distribution mechanism of loading, tooth profile correction and hardness had already been carried out for the preparation of design data.
The performance test of designed gear was done by back-to-back locked torque testing apparatus.
Obtained test results are as follows:
(1) Endurance running tests for 100 hours were successfully done with tooth loading 1000 psi for K-value as maximum.
(2) Profile corrections were properly chosen on teeth of gear for heavy loading.
(3) Equal distribution ratios of loading were within 3.4%, and 2.43% as mean.
(4) Technical data necessary for small and light epicyclic gears were obtained. Using those data, the marine epicyclic gear of 800 psi for K-value is designed half in weight and 1/1.26 in volume compared with the same conventional type of 400 spi.

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An advanced stern bearing system using a spherical roller bearing has been developed after a series of tests on a test rig. This new bearing system was installed on a 1600 DWT cargo ship and has been in actual service since August, 1976.
Thus its high reliability has been established.

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The sleeve of the propeller shaft of the T.S. Shintoku Maru was renewed due to corrosion found over its surface on the occasion of her third regular inspection in February 1975.
For reader's reference, this paper covers a detailed report of the said renewal case and a consideration on it on the basis of material test results of the removed sleeve and some data collected from other cases of identical trouble.

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This report gives the results of experimental studies that have been carried out under the static and dynamic load condition by utilizing a large bearing test apparatus with the bearing of 1, 200 mm diameter to obtain various characteristics of oil lubricated stern tube bearing.
The presented characteristics are as follows.
(1) Oil lubricated characteristics under the static and dynamic load condition
(2) Friction characteristics and stick slip at engine starting
(3) Results of the continuous rotating test which closely resembled a bearing load condition of high power ship

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Whitemetal is a superior material in conformability, embeddability and compatibility. It is commonly used for ship's large bearings such as stern tube bearings, for it is easy to get the comparatively refined and uniform matrix when it is employed in large bearings. The thickness of whitemetal is employed usually 3 to 4 millimeters, but it is not certain how the thickness of whitemetals is estimated in terms of fatigue strength.
This paper we describes an experimental study of fatigue behavior of whitemetal bearings. The fatigue tests of tin-base and lead-base whitemetal bearings by giving alternating load have been performed and the metal damage ratings as to material, thickness and lining have been examined.

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In Japan, the keyless type propeller was seldom adopted until 1970 however since then has become very popular as its reliability was proven greatly by having improved the conspicuous disadvantages of the conventional keyed type propeller.
The Keyless Propeller Development Committee was organized with a membership drawn from representatives of Ministry of Transportation, NK, Shipowners, Shipbuilders and other experts under the financial assistance of the Japan ship Machinery Development Association.
The Committee studied on a fundamental and practical level the problem of developing keyless propellers. The successful result of this research made the first keyless propeller in Japan that in August, 1971 was installed on M.V. “KISSYU MARU” of Satokuni Kisen K. K., Hull No. 232 of Onomichi Dockyard.
Till this moment, it was equipped on more than 500 vessels in Japan. It is strongly recommended that all the ships newbuilding in future will equip the keyless type propeller with many technical advantages.

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Since the past years, rubber bearing has been adopted for various such as ferry boat, fishing boat, navy vessel, etc. as a water lubricated strut bearing and stern tube bearing. However, there was restriction of a certain degree in application of the said bearing due to mainly costwise matter, i.e. the same is much expensive compared with conventional bearing of lignumvitae.
Recently, the demands for water lubricated rubber bearing is ever-increasing in place of white metal bearing taking prevention of the oil pollution into consideration.
In keeping with the above trend, an investigation on wear down and condition of the bearing contact for the rubber bearing has been made, leading to the following summeries:
(1) Wear down of rubber bearing is approximately 0.4-0.5 mm per year.
(2) The contact seems to be good enough for service, and whose condition proves to be almost the same as that of white metal bearing being slope bored.

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Recently, in order to improve circumstances for sailor, reducing vibration and noise will be required.
As a method of reducing a propeller induced force, Highly Skewed Propeller is investigated. This paper presents some aspects of Highly Skewed Propeller applied for controllable pitch propeller and then some advantages and test results regarding Highly Skewed Propeller are introduced by basing the investigations at DTNSRDC in the United States and our model test. Highly Skewed Propeller applied for controllable pitch propeller has backward and forward skew, in order to reduce spindle moment for blades without compromising the advantages of propeller skew (cavitation and vibration improvement) .
Model experimental results and full scale results by KaMeWa propeller are presented which the advantages of Highly Skewed Propeller are confirmed for controllable pitch propeller, too.

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According to the recent depression of shipping market, the economization, such as the improvement of propulsion plant, the manpower in operation and the saving of the fuel oil consumption, has been investigated, and consequently CPP (Controllable Pitch Propellers) have been applied on the many general merchant ships.
IHI have manufactured IHI-LIPS CPP under the licensee of LIPS B.V. in Holland for the multi-purpose standard cargo ships named “FRIENDSHIP” and “FREEDOM MARK II”, and 60, 000 DWT Energy-saving tankers etc. since 1976.
This paper explains the basic specifications of CPP comparing with FPP (Fixed Pitch Propellers) for general merchant ships.

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It has been well known among propeller designers that propellers must be designed so as to prevent any possibility of overloading the main engine even the required engine power increases owing to the increased frictional losses on ship's hull and propeller itself during service.
On the other hand, propeller designers recently wonder if an allowable load of the engine is very limited and an allowable overload duration becomes more and more short.
Taking consideration of the above, Propeller and Shafting Committee has made inquiries about their design criteria to the major diesel and steam turbine main propulsion machinery manufacturers in Japan relative to the following items;
1) Main engine allowable operating range of manufacturer's standard.
2) Main engine performance drop by aging.
3) Recommended allowance for propeller design against aging.
4) Relations between propeller rpm drop in service and main engine allowable operating range.
5) Possibility of improving the main engine allowable operating range.

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Icebreaker “Fuji” works for the support of antarctic research action after her completion in 1965. There were propeller-blade damages two times due to heavy ice condition during thirteen years operation.
On the 18th research (1976-1977), two engineers (Authors) were permitted to go on board “Fuji” for studying ice-navigation in Antarctic region. This paper discusses the ice-navigation and studies the strength of propeller-blade and propeller shaft of “Fuji” in ice.

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