青函連絡船洞爺丸等の転覆事件に関する実験的研究

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Typhoon "Marie" capsized five ferry-boats including Toya Maru at Hakodate Harbour in the night of September 26,1954. The disaster was so great that it invited a serious public attention.In accordance with the request of the Marine Disaster Inquiry Agency, the authors conducted experiments in order to investigate its technical causes. In the experiments two specific cases of Toya Maru (passenger boat) and Tokachi Maru (freighter) were dealt with as representatives of the wrecked ferry-boats.The main interest of this experiment was focused on the following items.(1) To study the mechanism and to measure the amount of water poured in through the stern opening of the wagon deck, while the ship anchoring, heaving-to or advancing in waves.(2) To study the effect of water stagnant on the wagon deck or flooded in the engine and boiler rooms on the stability of a ship(3)To study the effect of bottom contact on the stability of a ship, in case of Toya Maru. From these investigations, a number of problems have been clarified or could be presumed with a good confidence, which may be outlined as follows.1. Flooding on the wagon deck at the time of anchoring was caused by the dipping-up of the water due to pitching of the ship. Such flooding is the heaviest when the wave length is approximately equal to the length of the ship, and the deck would not be flooeded unless the ship is in full loaded condition and the wave height is more than 5 metres.2. It is presumed that the wave at the time of disaster was such that the length was approx imately equal to the length of the ship, that is, 100 metres or thereabout, and the height was about 6 metres.3. In case of freighters (Tokachi Maru type), there is a certain danger that, when the wave height is more than 6 metres and the wave period is about 9 seconds, the ship overturns merely due to the flooding of sea water onto the wagon deck through the stern opening. It is considered that this is the reason why all of 4 freighters capsized and sank as they dropped anchors at the offing and stood facing with wind and waves.On the contrary, in case of passenger ferrys (Toya Maru type), the breadth of the wagon space is so narrow that they do not result in capsize merely due to the flooding of the waves.The reason why Toya Maru did not overturned until she had drifted to the shore and then contacted the bottom would be this as well as the fact that the accomodation spaces were located at the both sides of the wagon deck , which contributed to the stability of the ship.4. It is generally throught that, when the ship encounters with wind storm, it is the safest way that the ship stands facing with the wind and waves. However, this would aggravate the danger in case of ships having stern openings.5. According to the statements of survivors of Tokachi Maru, GM was presumed to have been negative before capsizing due to the stagnation of water on the wagon deck and the flooding in engine and boiler rooms.6. In case of Toya Maru there is little probability that wind and waves then would cause her capsize merely due to the flooding, just before her bottom contact, of the assumed amount of about 200 tons in engine and boiler rooms and about 300 tons on the wagon deck. The vital cause is assumed to be the loss of stability affected by the bottom contact.
社団法人日本船舶海洋工学会の論文

青函連絡船洞爺丸等の転覆事件に関する実験的研究

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