Increasing demand for higher output and better fuel efficiency forces maximum combustion pressure of the engine higher and higher, requesting the same or even more reliability to the engine.
At present mono block castiron cylinder liners are widely used for marine slow speed diesel engines simply because of their tribological superior characteristics.
This paper introduces a solution of double layer cylinder liner by HIP (Hot Isostatic Pressing) method. This liner consists of two different materials. Inside material is tribologicaly superior material, in this case castiron. On the other hand outside material is strong material. Inside and outside material are fixed together using HIP method. The successful test results using test engine and production engine were also explained here.

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There seems to be a very delay in the automation of boiler water treatment compared to other domains of ship techniques. The difficulties of monitering the boiler water quality is considered to be one of main reasons of such delayed situation. As for marine boiler, most of impulities of boiler water are due to mixing of sea water. A basic experimental study was carried out in order to investigate effects of sea water mixing on boiler water qualities, especially on pH, concentrations of phosphoric ion PO^3-₄and of chloric ion Cl^-, and electric conductivity EC. The obtained results are (1) theoretical estimation of Cl^- change almost agreed with experimental results, (2) theoretical estimation of pH was valid when pH was in the range larger than 10, (3) as for PO^3-₄, some discrepancies between theory and experiment were observed, and decrease of PO^3-₄, obtained by the latter was larger than that predicted by the former, (4) the flow-through type sensors were confirmed to be useful for monitoring pH and EC when flow velocity was regulated carefully so as to avoid the influence of streaming potential. According to those obtained results, there would be the possibility to advance the automatic control of water quality of marine boiler by monitoring pH and EC.

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The so-called“soot fire”, whichi is a heating surface melt-down failure of the exhaust gas economizer (EGE) of diesel ship, is so serious that it has been urgently waiting for effective countermeasures. This report developes a simulation model in order to investigate the sootburning and heat transfer process in the EGE, of which heating surface consists of finned tubes with parallel arrangement. The heat transfer equation of the model takes into consideration 4 factors, that is, the heat transported by the gas flow, the heat transmitted from gasside to waterside, the heat being accumulated in the finned tube materials, and the heat released by the soot burning. The soot burning was modelled by a surface combustion of a soot layer deposited on heating surface. The simulation model can explain successfully various empilical facts reported so far regarding actual ship's soot fire failures. The calculation results give valuable informations regarding the influences of gasside and waterside heat transfer coefficients, gas flow rate, soot carolific value, soot deposition thickness etc. Among them, the waterside heat transfer coefficient, that is, the condition of water circulation shows the most definite influence on the soot burning, and it is made clear that the soot burning cannot occur the melt-down failure when the water circulation is sufficient to prevent the dryout.

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The oil purifier has always been one of the most essential auxiliary machines for marine use, employed for purifying the fuel oil and lubricating oil for the main engine and the diesel engine for generator primarily.
As a result of changes in the demand for various petroleum products in recent years and the advances in oil refinery technology for adaptation to such changes, low-grade heavy fuel oil is now used, which has high vicosity and high density.
The sludge content of the fuel oil is rather high, and it contains FCC catalyst, and various other problems are also encountered. All these must be overcome not only by special provision in the engine design but also by a new fuel oil treatment system including an oil purifier and other fuel oil treatment devices.
On the other hand, navigation with a small-size crew for better economy, typified by the“pioneer ship plan”in Japan, seems to be the order of the day, and that calls for higher reliability and a maintenance work saving.
Taking these conditions into account, this paper will focus attention on“countermeasure to change of enviroment on oil purifier”, which have been recently developed.

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On the chemichal tanker, if tanks containing chemical substances or mixtures are to be washed, the resulting residues shall be discharged to a reception facility until the concentration of the substance in the effluent to such facility is at or below the residual concentration orescribed for that substance and until the tank is empty. Any water subsequently added to the tank may be discharged into sea when the prescribed conditions are satisfied. So it is beneficial to wash tanks efficiently with a small quantity of washwater.
Then a means is investigated by using a small diameter nozzle washing machine and a Drocedure utilizing tank washing with recirculation of washwater is examined.
On the other hand, it is effective to decrease the amount of residue in the tank. Then the mount of residue in the tank is estimated by the results of the model tank test. And it is shown hat the necessary quantity of washwater is decreased by the accurate estimation of the residual quantity.

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