The study of a propulsion system by fin stroke like fish, dolphins and birds is a kind of application of organic phenomena to mechanics. The propulsion system by fin stroke, which has such advantages as safety and silence compared with a common screw propeller, is applied to propulsive systems of ships.
In this work, theoretical analysis of a simple two-dimensional oscillating wing model is described; the relationship between fin's behavior and its thrust is experimentally obtained; several new propulsion systems are examined on their practicality with loaded on a 3.5 m long boat.
In result, (1) the mean thrust generated by fin stroke is simply expressed by the theoretical equation which coincides an experimental one. (2) The mean thrust and the propulsive efficiency increased when the fin's angle of deviation has a phase delay. (3) The mean thrusts by propulsion system by fin stroke on the boat were almost similar to those by a common screw in the condition of the same wing area and in a low speed range.
Thus, the fin stroke system was proved to be applicable for propulsion of safe and silent ships.

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In compliance with“International Convention for the Prevention of Pollution from ships, 1973”, regulations of each governments are going to be revised severe and many equipments treating oily water have been developed.
This committee collected the information regarding engine room oily water treatment, that is; bilge treatment system of each ship-builders, bilge separators and monitors developed by manufacturers, principle of separating and monitoring, and concerned regulations, and classified these data, and compiled as manual for planning the engine room bilge system.
The summary of this manual will be introduced here on following items.
1. System and arrangement of engine room bilge treatment.
2. Principle of oily water separating and classification of existing separating units.
3. Principle of oil content monitoring and classification of existing monitors.
4. Summary of concerned regulations.

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