Recently an air lubrication method (ALM) has been recognized as one of promising techniques to save energy in naval engineering. In the present article, a brief introduction of ALM in naval architecture is presented. Since ALM requires the additional power to inject air bubble beneath the ship bottom, an air supply method with much less energy consumption should be a key technology to make ALM be promising method for large ships. A scavenge gas bypass method is proposed as one of breakthrough technologies. In the article, recent application of ALM to large commercial ships, including the scavenge gas bypass system, is introduced.

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Developments of natural resources in the Arctic region are becoming active in the recent years. Commercial use of the northern sea route is taking on realness with a decrease of sea ice area along the Arctic coast. Also Arctic and Antarctic observation is important to clarify a global climatic change. Icebreakers are indispensable to the support for the development, the escort for cargo ships and the polar observation in ice-covered waters. The technology on icebreaker's performance is improving steadily, responding to those missions. This paper shows the typical characteristics of icebreaker and introduces several technologies to improve the performance.

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This introduction contains the history of building very large crude-oil carrier (VLCC) at IHI Marine United Inc. (IHIMU), the outline of present VLCC “Idemitsumaru” and environmentally friendly ship of “eFuture 310T” developed by IHIMU. The “eFuture 310T” was developed so that 30% reduction of GHG is attained by integrating the technology of IHIMU such as advanced contra rotating propeller, tip raked propeller, rudder bulb and semicircular duct, waste heat recovery system, whaleback bow and air resistance reducing vane.

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Applications of multi-phase flow technologies to clean marine engineering are introduced. Large efforts have been made to reduce CO2, SOx, NOx and Particulate matter (PM) emissions from marine diesel engines. Urea Selective Catalytic Reduction (SCR) system is one of the most promising technology to largely reduce NOx emission. PM in exhaust gas may deposit on a honeycomb SCR catalyst, which increases pressure drop, blocks the flow area and decreases NOx reduction performance. Air blow (soot blow) can be effective for removing PM on a catalyst. An experimental investigation confirms that (1) large pore diameter of SCR catalyst and optimum exhaust gas velocity prevent PM accumulation, (2) PM accumulates mainly at the inlet and exit of the catalyst, and (3) high pressure soot blow removes PM.

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The authors have created new type of electric boat “RAICHO-S” in 2011. The craft has some special and unique features that set it apart from existing electric boats or battery-powered boats. First, she utilizes a lithium-ion battery with plug-in system or a rapid charging system. A dockside-mounted rapid charger can bring the boat’s battery up to 80% of full charge within 30 minutes, which is a much shorter time than is possible under conventional charging systems. The boat can operate for 45 minutes and berth for 30 minutes in a cyclic operation. The powerful lithium-ion battery gives the boat a running speed capability of around 10 knots, enabling it to navigate not only in flat-surface waters but also in open sea conditions where wind and waves prevent operation by conventional battery-powered craft. “RAICHO-S” utilizes a water jet propulsion system driven by electric motor whose advantages are safety for the diver, passing floating rope on fish preserve, environmental reservation (no-damage on leafs, fishes, and aquatic plants) and causing no cavitation. The disadvantage of water jet driven by combustion engine in low efficiency and low maneuverability at low speed can be overcome by use of electric motor.

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During the Tohoku earthquake, the tsunami had created a large scale seabed scour at the entrance of the port of Hachinohe in Japan. This damage would pose a problem to the safety of the navigation ships. So it was necessary to carry out a backfill work with dredged sand to ensure the safety of the navigation ships. Hence we introduced the construction method of dredging and filling by using cutter suction dredger and sand filling vessel. This method was carried out using a filled sand which was dredged by cutter suction dredger and then delivered via discharge pipe to the sand filling vessel. It was then placed on the designated area using tremie pipe which was equipped on the sand filling vessel.

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The present paper reports the fundamental research for the sterilization treatment of marine bacteria contained in ships’ ballast water. In the field of maritime sciences, destruction of marine ecosystem caused by sea creatures carried in ships’ ballast water to different seas is a serious international problem. In order to solve the problem, a new sterilization technique using shock wave and microbubble is proposed to develop more secure and environmentally friendly treatment method for ships’ ballast water. This method applies mechanical and chemical effects of shock pressures and free radicals generated by contraction and collapse of microbubbles to marine bacteria. Our previous and ongoing works are presented and prospective approaches that need to be solved the problems are described.

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