This paper describes field test on behavior of the large barge when its sand and soil is dumped the sea for getting the fundamental data on the occurence of turbidity adopted to model-tests.
　The test was carried out at Rokko Island in Kobe city on two barges, a 2,000t barge and a 2,500t barge. The rising acceleration and the change of draft of the barges under the operation measured.
　The risting velocity was obtained directly by integrating the rising acceleration. which was resulted to find the Floude Number under the dumping situation. It is cleaned that the change of the amount of its sand and soil with time is equivalent to the change of a decrease in buoyancy. The test showed that it took about 11 sec for the 2,500t barge to unload all its sand and soil.
　The results of the test gives the scale ratio based on the Froude's Law for the model-test.