Tunnel fin equals less ballast

A 30,000 dwt chemical tanker under construction at the Japanese shipyard of Shin Kurushima will be installed with a ?tunnel fin? when it is delivered to local shipping company Iino Kaiun Kaisha at the end of 2002. The fin, which is shaped like a semi-elliptical long tunnel fitted on the after section of the hull is close to the propeller and is designed to push the stern deeper in the water when the vessel is underway. The owner claims that the system will make it possible to reduce the amount of ballast by more than 20% when the vessel is sailing empty. According to the shipbuilder, this will be the first time such a vessel will mount a fin to reduce the volume of ballast and thus fuel costs. The normal amount of ballast needed to submerge the ship?s propeller is about 14,000t but, if fitted with the tunnel fin, the vessel will need only about 11,000t. The stainless steel chemical tanker is based on the same design as two previously completed sister-ships in 1999. Iino has decided to have the third tanker equipped with the tunnel fin to save fuel when sailing in ballast on the shuttle service between Asia and Saudi Arabia. Shin Kurushima, by using its own water tank, has developed various types of fins ranging from 5% to 15% of the ship length.